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Bleeding LCD displays
Cause and any amelioration, short of draining the liquid and starting
again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? |
Bleeding LCD displays
On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote:
Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) heh for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? That's been a problem with older LCD displays on Fluke DMMs as well. My old 8050A is starting to exhibit those symptoms, despite having been indoors all of its life. It's ameliorated somewhat on mine when the display is energized for a few hours; the dark areas retreat and become somewhat dimmer. Not a permanent solution, but you might try that. Hook one up to an external supply (they are battery powered?) and let it run over a weekend to see if there's any improvement. There are several hacks around the 'net where folks have replaced the LCD module with a bank of 7-segment LEDs. What I'll probably try is to fit an EADog 1x8 LCD module in place of the original, with a small micro to handle the display initialization and character translation. The EADog is 55 x 31 x 2 mm, a good fit for the 8050A. |
Bleeding LCD displays
On 02/03/2014 15:41, Rich Webb wrote:
On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) heh for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? That's been a problem with older LCD displays on Fluke DMMs as well. My old 8050A is starting to exhibit those symptoms, despite having been indoors all of its life. It's ameliorated somewhat on mine when the display is energized for a few hours; the dark areas retreat and become somewhat dimmer. Not a permanent solution, but you might try that. Hook one up to an external supply (they are battery powered?) and let it run over a weekend to see if there's any improvement. There are several hacks around the 'net where folks have replaced the LCD module with a bank of 7-segment LEDs. What I'll probably try is to fit an EADog 1x8 LCD module in place of the original, with a small micro to handle the display initialization and character translation. The EADog is 55 x 31 x 2 mm, a good fit for the 8050A. This display is actually on a CD unit. Its not been used for some time so may be what you say. Its also on the lower part of the display, perhaps turning the CD upside down, when not in use, may help. At the moment the black splodge is not intruding into an information area, but I assume it will eventually |
Bleeding LCD displays
On Sun, 02 Mar 2014 16:43:19 +0000, N_Cook wrote:
This display is actually on a CD unit. Its not been used for some time so may be what you say. Its also on the lower part of the display, perhaps turning the CD upside down, when not in use, may help. At the moment the black splodge is not intruding into an information area, but I assume it will eventually I don't think gravity helps... The display on the 8050A here is darkening from the top, down. Looks almost like mildew/fungus growing down from the top, intruding into the spaces between the segments. |
Bleeding LCD displays
On 02.03.14 13:55, N_Cook wrote:
Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? Apply 30 atm in a pressure chamber, then wait a few hours. |
Bleeding LCD displays
On 02/03/2014 20:25, Sjouke Burry wrote:
On 02.03.14 13:55, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? Apply 30 atm in a pressure chamber, then wait a few hours. makes some sort of sense, I always assumed the sun-heating business was making the fluid expand and force open the seal between the glass sections. OK, so apply your high and even-handed pressure but how to stop the glasses separating again? |
Bleeding LCD displays
On 02.03.14 22:04, N_Cook wrote:
On 02/03/2014 20:25, Sjouke Burry wrote: On 02.03.14 13:55, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? Apply 30 atm in a pressure chamber, then wait a few hours. makes some sort of sense, I always assumed the sun-heating business was making the fluid expand and force open the seal between the glass sections. OK, so apply your high and even-handed pressure but how to stop the glasses separating again? The fluid tends to stay in place,it likes the glass sheets. Years ago I made lcd glasses, to switch the visual field in experiments. Production:Separate the glass with a thin mylar film(dupont), glue two opposite sides with 5 min epoxy, remove the mylar, then put a small drop of lcd fluid on one of the open sides. And a miracle happens, the drop gets sucked between the glasses(~10 minutes) very slowly. Then clean the open sides, and apply epoxy to them as well. Worked for me. So only pressure or heat tends to drive the fluid out. Bad mounting can cause unwanted pressure and damage. The air pressure repair works, if the fluid is still present around the leak, else you are out of luck. |
Bleeding LCD displays
On 03/02/2014 1:26 PM, Sjouke Burry wrote:
On 02.03.14 22:04, N_Cook wrote: On 02/03/2014 20:25, Sjouke Burry wrote: On 02.03.14 13:55, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? Apply 30 atm in a pressure chamber, then wait a few hours. makes some sort of sense, I always assumed the sun-heating business was making the fluid expand and force open the seal between the glass sections. OK, so apply your high and even-handed pressure but how to stop the glasses separating again? The fluid tends to stay in place,it likes the glass sheets. Years ago I made lcd glasses, to switch the visual field in experiments. Production:Separate the glass with a thin mylar film(dupont), glue two opposite sides with 5 min epoxy, remove the mylar, then put a small drop of lcd fluid on one of the open sides. And a miracle happens, the drop gets sucked between the glasses(~10 minutes) very slowly. Then clean the open sides, and apply epoxy to them as well. Worked for me. So only pressure or heat tends to drive the fluid out. Bad mounting can cause unwanted pressure and damage. The air pressure repair works, if the fluid is still present around the leak, else you are out of luck. I could see using a vacuum pump first (LCD in a bath of fluid) to draw out any air. Then, with the LCD still bathed in the replacement fluid, pressurized to the 30ATM to force the liquid back in. Then seal with whatever works best. John :-#)# -- (Please post followups or tech inquiries to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
Bleeding LCD displays
On 03/03/2014 08:18, John Robertson wrote:
On 03/02/2014 1:26 PM, Sjouke Burry wrote: On 02.03.14 22:04, N_Cook wrote: On 02/03/2014 20:25, Sjouke Burry wrote: On 02.03.14 13:55, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? Apply 30 atm in a pressure chamber, then wait a few hours. makes some sort of sense, I always assumed the sun-heating business was making the fluid expand and force open the seal between the glass sections. OK, so apply your high and even-handed pressure but how to stop the glasses separating again? The fluid tends to stay in place,it likes the glass sheets. Years ago I made lcd glasses, to switch the visual field in experiments. Production:Separate the glass with a thin mylar film(dupont), glue two opposite sides with 5 min epoxy, remove the mylar, then put a small drop of lcd fluid on one of the open sides. And a miracle happens, the drop gets sucked between the glasses(~10 minutes) very slowly. Then clean the open sides, and apply epoxy to them as well. Worked for me. So only pressure or heat tends to drive the fluid out. Bad mounting can cause unwanted pressure and damage. The air pressure repair works, if the fluid is still present around the leak, else you are out of luck. I could see using a vacuum pump first (LCD in a bath of fluid) to draw out any air. Then, with the LCD still bathed in the replacement fluid, pressurized to the 30ATM to force the liquid back in. Then seal with whatever works best. John :-#)# If I can find a salvaged one that has bled over time, I will try covering the pins with card and then a bicycle inner tube each side of the glass,held in a vice and inflated, and see what happens. Then leave it for a few hours, then release pressure and see what happens over the months |
Bleeding LCD displays
On 03.03.14 9:18, John Robertson wrote:
On 03/02/2014 1:26 PM, Sjouke Burry wrote: On 02.03.14 22:04, N_Cook wrote: On 02/03/2014 20:25, Sjouke Burry wrote: On 02.03.14 13:55, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? Apply 30 atm in a pressure chamber, then wait a few hours. makes some sort of sense, I always assumed the sun-heating business was making the fluid expand and force open the seal between the glass sections. OK, so apply your high and even-handed pressure but how to stop the glasses separating again? The fluid tends to stay in place,it likes the glass sheets. Years ago I made lcd glasses, to switch the visual field in experiments. Production:Separate the glass with a thin mylar film(dupont), glue two opposite sides with 5 min epoxy, remove the mylar, then put a small drop of lcd fluid on one of the open sides. And a miracle happens, the drop gets sucked between the glasses(~10 minutes) very slowly. Then clean the open sides, and apply epoxy to them as well. Worked for me. So only pressure or heat tends to drive the fluid out. Bad mounting can cause unwanted pressure and damage. The air pressure repair works, if the fluid is still present around the leak, else you are out of luck. I could see using a vacuum pump first (LCD in a bath of fluid) to draw out any air. Then, with the LCD still bathed in the replacement fluid, pressurized to the 30ATM to force the liquid back in. Then seal with whatever works best. John :-#)# You cant replace the fluid, the pressure treatment just tries to force back in what was there in the first place. Maybe. The fluid had a price tag of 500 dollars for 4 cubic centimetres, and has wildly different specs for various lcd's, so forget getting new fluid. My lcd's switched between transparent and milky, and did not use polarization.Working voltage 500 volt AC!!!!! on/off. Also checking the mount for unwanted pressure points does improve things. |
Bleeding LCD displays
no change with unconfined inner tube pressure. Decided to squash the LCD
(no pins attached to this one) between 2 pieces of silicone rubber in the engineering vice. Cleaned the rubber but did not think to clean the vice faces or add some card or something, must have been a bit of grit and crack, so end of that experiment. I only found one salvaged LCD wiht a black splodge |
Bleeding LCD displays
"Rich Webb" wrote in message ... On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) heh for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? That's been a problem with older LCD displays on Fluke DMMs as well. My old 8050A is starting to exhibit those symptoms, despite having been indoors all of its life. It's ameliorated somewhat on mine when the display is energized for a few hours; the dark areas retreat and become somewhat dimmer. Same on my Sharp EL5100 calculator - it was a present in my college days and has sentimental value, otherwise I'd have binned it. Apparently there are salvage LCD panels out there, but hard to justify the cost when I have a pile of calculators in assorted shapes & sizes. |
Bleeding LCD displays
"N_Cook" wrote in message ... On 02/03/2014 15:41, Rich Webb wrote: On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) heh for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? That's been a problem with older LCD displays on Fluke DMMs as well. My old 8050A is starting to exhibit those symptoms, despite having been indoors all of its life. It's ameliorated somewhat on mine when the display is energized for a few hours; the dark areas retreat and become somewhat dimmer. Not a permanent solution, but you might try that. Hook one up to an external supply (they are battery powered?) and let it run over a weekend to see if there's any improvement. There are several hacks around the 'net where folks have replaced the LCD module with a bank of 7-segment LEDs. What I'll probably try is to fit an EADog 1x8 LCD module in place of the original, with a small micro to handle the display initialization and character translation. The EADog is 55 x 31 x 2 mm, a good fit for the 8050A. This display is actually on a CD unit. Its not been used for some time so may be what you say. Its also on the lower part of the display, perhaps turning the CD upside down, Once I repaired TVs for a back street bodger - a CTV came in with a rainbow pattern on the picture and no amount of degaussing did any good. For some reason I up-ended the TV, the picture improved a lot, so I turned it completely upside down and the picture was perfect. We took the CRT out and put it back upside down, then slackend the yoke clamp and rotated that 180 deg, the purity rings needed a tweak but all was well - so we wedged a lino tile between the anode cap and PCB to stop it cracking over, and cased it up. |
Bleeding LCD displays
"Rich Webb" wrote in message ... On Sun, 02 Mar 2014 16:43:19 +0000, N_Cook wrote: This display is actually on a CD unit. Its not been used for some time so may be what you say. Its also on the lower part of the display, perhaps turning the CD upside down, when not in use, may help. At the moment the black splodge is not intruding into an information area, but I assume it will eventually I don't think gravity helps... The display on the 8050A here is darkening from the top, down. Looks almost like mildew/fungus growing down from the top, intruding into the spaces between the segments. I have a calculator with "black clouds" gathering along the top edge of the LCD. Activating any segment/symbol clears a halo around it for a while. When I asked about this on various groups a while ago - a few people suggested failing edge seal letting moisture contaminate the liquid crystal. |
Bleeding LCD displays
On 03/03/2014 1:39 AM, Sjouke Burry wrote:
On 03.03.14 9:18, John Robertson wrote: On 03/02/2014 1:26 PM, Sjouke Burry wrote: On 02.03.14 22:04, N_Cook wrote: On 02/03/2014 20:25, Sjouke Burry wrote: On 02.03.14 13:55, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? Apply 30 atm in a pressure chamber, then wait a few hours. makes some sort of sense, I always assumed the sun-heating business was making the fluid expand and force open the seal between the glass sections. OK, so apply your high and even-handed pressure but how to stop the glasses separating again? The fluid tends to stay in place,it likes the glass sheets. Years ago I made lcd glasses, to switch the visual field in experiments. Production:Separate the glass with a thin mylar film(dupont), glue two opposite sides with 5 min epoxy, remove the mylar, then put a small drop of lcd fluid on one of the open sides. And a miracle happens, the drop gets sucked between the glasses(~10 minutes) very slowly. Then clean the open sides, and apply epoxy to them as well. Worked for me. So only pressure or heat tends to drive the fluid out. Bad mounting can cause unwanted pressure and damage. The air pressure repair works, if the fluid is still present around the leak, else you are out of luck. I could see using a vacuum pump first (LCD in a bath of fluid) to draw out any air. Then, with the LCD still bathed in the replacement fluid, pressurized to the 30ATM to force the liquid back in. Then seal with whatever works best. John :-#)# You cant replace the fluid, the pressure treatment just tries to force back in what was there in the first place. Maybe. The fluid had a price tag of 500 dollars for 4 cubic centimetres, and has wildly different specs for various lcd's, so forget getting new fluid. My lcd's switched between transparent and milky, and did not use polarization.Working voltage 500 volt AC!!!!! on/off. Also checking the mount for unwanted pressure points does improve things. Ah, thanks, that clears up why no-one is resurrecting them... John :-#)# -- (Please post followups or tech inquiries to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
Bleeding LCD displays
"John Robertson" wrote in message ... On 03/03/2014 1:39 AM, Sjouke Burry wrote: On 03.03.14 9:18, John Robertson wrote: On 03/02/2014 1:26 PM, Sjouke Burry wrote: On 02.03.14 22:04, N_Cook wrote: On 02/03/2014 20:25, Sjouke Burry wrote: On 02.03.14 13:55, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? Apply 30 atm in a pressure chamber, then wait a few hours. makes some sort of sense, I always assumed the sun-heating business was making the fluid expand and force open the seal between the glass sections. OK, so apply your high and even-handed pressure but how to stop the glasses separating again? The fluid tends to stay in place,it likes the glass sheets. Years ago I made lcd glasses, to switch the visual field in experiments. Production:Separate the glass with a thin mylar film(dupont), glue two opposite sides with 5 min epoxy, remove the mylar, then put a small drop of lcd fluid on one of the open sides. And a miracle happens, the drop gets sucked between the glasses(~10 minutes) very slowly. Then clean the open sides, and apply epoxy to them as well. Worked for me. So only pressure or heat tends to drive the fluid out. Bad mounting can cause unwanted pressure and damage. The air pressure repair works, if the fluid is still present around the leak, else you are out of luck. I could see using a vacuum pump first (LCD in a bath of fluid) to draw out any air. Then, with the LCD still bathed in the replacement fluid, pressurized to the 30ATM to force the liquid back in. Then seal with whatever works best. John :-#)# You cant replace the fluid, the pressure treatment just tries to force back in what was there in the first place. Maybe. The fluid had a price tag of 500 dollars for 4 cubic centimetres, and has wildly different specs for various lcd's, so forget getting new fluid. My lcd's switched between transparent and milky, and did not use polarization.Working voltage 500 volt AC!!!!! on/off. Also checking the mount for unwanted pressure points does improve things. Ah, thanks, that clears up why no-one is resurrecting them... If there are pressure points on the LCD panel, the effect should vary if the outer casing is flexed. My calculator that has gathering clouds at the top of the LCD spent a fair bit of time in my back pocket - the suggestion of cracked edge seal and moisture ingress is possibly right. |
Bleeding LCD displays
Ian Field wrote:
"N_Cook" wrote in message ... On 02/03/2014 15:41, Rich Webb wrote: On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) heh for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? That's been a problem with older LCD displays on Fluke DMMs as well. My old 8050A is starting to exhibit those symptoms, despite having been indoors all of its life. It's ameliorated somewhat on mine when the display is energized for a few hours; the dark areas retreat and become somewhat dimmer. Not a permanent solution, but you might try that. Hook one up to an external supply (they are battery powered?) and let it run over a weekend to see if there's any improvement. There are several hacks around the 'net where folks have replaced the LCD module with a bank of 7-segment LEDs. What I'll probably try is to fit an EADog 1x8 LCD module in place of the original, with a small micro to handle the display initialization and character translation. The EADog is 55 x 31 x 2 mm, a good fit for the 8050A. This display is actually on a CD unit. Its not been used for some time so may be what you say. Its also on the lower part of the display, perhaps turning the CD upside down, Once I repaired TVs for a back street bodger - a CTV came in with a rainbow pattern on the picture and no amount of degaussing did any good. For some reason I up-ended the TV, the picture improved a lot, so I turned it completely upside down and the picture was perfect. We took the CRT out and put it back upside down, then slackend the yoke clamp and rotated that 180 deg, the purity rings needed a tweak but all was well - so we wedged a lino tile between the anode cap and PCB to stop it cracking over, and cased it up. That reminds me of when people actually rebuilt or replaced picture tubes. Any good stories of tubes imploding? |
Bleeding LCD displays
I found another black splodged LCD, placed inside 2x sheets of silicone
rubber inside 2 slabs of cleaned thick perspex sheet in the vice and left over night. Splodge in one area broke into a pretty dotty fractal pattern over the whole display, then over minutes a fractally natural fern-like spots . Have not so far managed to activate any segments, assuming backplane is an end contact. I suspect the black will coaelesce back into a solid area over the next few hours |
Bleeding LCD displays
"Cydrome Leader" wrote in message ... Ian Field wrote: "N_Cook" wrote in message ... On 02/03/2014 15:41, Rich Webb wrote: On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) heh for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? That's been a problem with older LCD displays on Fluke DMMs as well. My old 8050A is starting to exhibit those symptoms, despite having been indoors all of its life. It's ameliorated somewhat on mine when the display is energized for a few hours; the dark areas retreat and become somewhat dimmer. Not a permanent solution, but you might try that. Hook one up to an external supply (they are battery powered?) and let it run over a weekend to see if there's any improvement. There are several hacks around the 'net where folks have replaced the LCD module with a bank of 7-segment LEDs. What I'll probably try is to fit an EADog 1x8 LCD module in place of the original, with a small micro to handle the display initialization and character translation. The EADog is 55 x 31 x 2 mm, a good fit for the 8050A. This display is actually on a CD unit. Its not been used for some time so may be what you say. Its also on the lower part of the display, perhaps turning the CD upside down, Once I repaired TVs for a back street bodger - a CTV came in with a rainbow pattern on the picture and no amount of degaussing did any good. For some reason I up-ended the TV, the picture improved a lot, so I turned it completely upside down and the picture was perfect. We took the CRT out and put it back upside down, then slackend the yoke clamp and rotated that 180 deg, the purity rings needed a tweak but all was well - so we wedged a lino tile between the anode cap and PCB to stop it cracking over, and cased it up. That reminds me of when people actually rebuilt or replaced picture tubes. Any good stories of tubes imploding? I always made the scrap ones safe by knocking the neck off. |
Bleeding LCD displays
Ian Field wrote:
"Cydrome Leader" wrote in message ... Ian Field wrote: "N_Cook" wrote in message ... On 02/03/2014 15:41, Rich Webb wrote: On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) heh for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? That's been a problem with older LCD displays on Fluke DMMs as well. My old 8050A is starting to exhibit those symptoms, despite having been indoors all of its life. It's ameliorated somewhat on mine when the display is energized for a few hours; the dark areas retreat and become somewhat dimmer. Not a permanent solution, but you might try that. Hook one up to an external supply (they are battery powered?) and let it run over a weekend to see if there's any improvement. There are several hacks around the 'net where folks have replaced the LCD module with a bank of 7-segment LEDs. What I'll probably try is to fit an EADog 1x8 LCD module in place of the original, with a small micro to handle the display initialization and character translation. The EADog is 55 x 31 x 2 mm, a good fit for the 8050A. This display is actually on a CD unit. Its not been used for some time so may be what you say. Its also on the lower part of the display, perhaps turning the CD upside down, Once I repaired TVs for a back street bodger - a CTV came in with a rainbow pattern on the picture and no amount of degaussing did any good. For some reason I up-ended the TV, the picture improved a lot, so I turned it completely upside down and the picture was perfect. We took the CRT out and put it back upside down, then slackend the yoke clamp and rotated that 180 deg, the purity rings needed a tweak but all was well - so we wedged a lino tile between the anode cap and PCB to stop it cracking over, and cased it up. That reminds me of when people actually rebuilt or replaced picture tubes. Any good stories of tubes imploding? I always made the scrap ones safe by knocking the neck off. I'm aware of one guy that broke a neck off, by accident at a shop, but nothing past that. I've got to check you tube for vidoes of people removing the steel band around a CRT. Not sure how you'd even weasel under one to cut it off, and from a safe distance, but somebody somewhere has to have tried. |
Bleeding LCD displays
On 03/04/2014 11:40 AM, Cydrome Leader wrote:
Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "N_Cook" wrote in message ... On 02/03/2014 15:41, Rich Webb wrote: On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) heh for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? That's been a problem with older LCD displays on Fluke DMMs as well. My old 8050A is starting to exhibit those symptoms, despite having been indoors all of its life. It's ameliorated somewhat on mine when the display is energized for a few hours; the dark areas retreat and become somewhat dimmer. Not a permanent solution, but you might try that. Hook one up to an external supply (they are battery powered?) and let it run over a weekend to see if there's any improvement. There are several hacks around the 'net where folks have replaced the LCD module with a bank of 7-segment LEDs. What I'll probably try is to fit an EADog 1x8 LCD module in place of the original, with a small micro to handle the display initialization and character translation. The EADog is 55 x 31 x 2 mm, a good fit for the 8050A. This display is actually on a CD unit. Its not been used for some time so may be what you say. Its also on the lower part of the display, perhaps turning the CD upside down, Once I repaired TVs for a back street bodger - a CTV came in with a rainbow pattern on the picture and no amount of degaussing did any good. For some reason I up-ended the TV, the picture improved a lot, so I turned it completely upside down and the picture was perfect. We took the CRT out and put it back upside down, then slackend the yoke clamp and rotated that 180 deg, the purity rings needed a tweak but all was well - so we wedged a lino tile between the anode cap and PCB to stop it cracking over, and cased it up. That reminds me of when people actually rebuilt or replaced picture tubes. Any good stories of tubes imploding? I always made the scrap ones safe by knocking the neck off. I'm aware of one guy that broke a neck off, by accident at a shop, but nothing past that. I've got to check you tube for vidoes of people removing the steel band around a CRT. Not sure how you'd even weasel under one to cut it off, and from a safe distance, but somebody somewhere has to have tried. When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. Great fun--glass _everywhere_. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net |
Bleeding LCD displays
"Cydrome Leader" wrote in message ... Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "N_Cook" wrote in message ... On 02/03/2014 15:41, Rich Webb wrote: On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) heh for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? That's been a problem with older LCD displays on Fluke DMMs as well. My old 8050A is starting to exhibit those symptoms, despite having been indoors all of its life. It's ameliorated somewhat on mine when the display is energized for a few hours; the dark areas retreat and become somewhat dimmer. Not a permanent solution, but you might try that. Hook one up to an external supply (they are battery powered?) and let it run over a weekend to see if there's any improvement. There are several hacks around the 'net where folks have replaced the LCD module with a bank of 7-segment LEDs. What I'll probably try is to fit an EADog 1x8 LCD module in place of the original, with a small micro to handle the display initialization and character translation. The EADog is 55 x 31 x 2 mm, a good fit for the 8050A. This display is actually on a CD unit. Its not been used for some time so may be what you say. Its also on the lower part of the display, perhaps turning the CD upside down, Once I repaired TVs for a back street bodger - a CTV came in with a rainbow pattern on the picture and no amount of degaussing did any good. For some reason I up-ended the TV, the picture improved a lot, so I turned it completely upside down and the picture was perfect. We took the CRT out and put it back upside down, then slackend the yoke clamp and rotated that 180 deg, the purity rings needed a tweak but all was well - so we wedged a lino tile between the anode cap and PCB to stop it cracking over, and cased it up. That reminds me of when people actually rebuilt or replaced picture tubes. Any good stories of tubes imploding? I always made the scrap ones safe by knocking the neck off. I'm aware of one guy that broke a neck off, by accident at a shop, but nothing past that. I've got to check you tube for vidoes of people removing the steel band around a CRT. Not sure how you'd even weasel under one to cut it off, and from a safe distance, but somebody somewhere has to have tried. Years ago I used to visit the local tip to pick up TVs to refurbish, once I found a set that I only wanted the PCB from, so the quickest way to remove the wooden cabinet and all the other unwanted stuff was with my steel toecap boot - during this procedure, the faceplate fell off the CRT - its literally only glued on! On another occasion someone I knew was minding the site while the regular bloke was away, I persuaded him to slowly advance the hydraulic ram in the compactor while I nipped a CRT diagonally across 2 corners between the ram and the opening in the container. Once I was safely out of the chute we switched the ram back on, the hydraulics did a great deal of heaving and grunting - meanwhile some bloke had gone up the steps to tip his rubbish, suddenly there was an almighty bang, the ground shook and the bloke was enveloped by a silver blizzard that used to be the metalisation inside the tube. I've seen photos online of the aftermath of an implosion on a CRT production line - apparently its possible for one imploding CRT to set off a chain reaction that destroys quite a few. |
Bleeding LCD displays
On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote:
Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? LCD panels have a slots at the bottom of the glass to help equalize inside to outside air pressure. If it were sealed shut, your laptop or tablet display would explode at altitude. One of my non-clever mistakes is to clean the screen of a warm running laptop display with a soapy water while in the upright position. As the screen cools, the soapy water is sucked into the panel via the bottom slots. Eventually, LCD leprosy forms along the bottom of the display. I have several panels like that, all from an office where the cleaning service washed down the LCD displays every night as part of the service. I would speculate (which means I haven't tried doing this) that it would be possible to use the partial vacuum effect to replenish the liquid in the display. I have no idea what's in the liquid or where to obtain a supply. Just remove the lower part of the panel frame, heat the panel, dump into some warm LCD liquid, and hope that it sucks the liquid into the panel as it cools. LCD Panel Rejuvenator (patent pending). The LCD panel manufactures could probably prevent the problem by simply adding a foam sponge along the slot to act as a reservoir. Incidentally, the fluid is reputed to be sticky and toxic. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Bleeding LCD displays
Cydrome Leader wrote:
Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "N_Cook" wrote in message ... On 02/03/2014 15:41, Rich Webb wrote: On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) heh for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? That's been a problem with older LCD displays on Fluke DMMs as well. My old 8050A is starting to exhibit those symptoms, despite having been indoors all of its life. It's ameliorated somewhat on mine when the display is energized for a few hours; the dark areas retreat and become somewhat dimmer. Not a permanent solution, but you might try that. Hook one up to an external supply (they are battery powered?) and let it run over a weekend to see if there's any improvement. There are several hacks around the 'net where folks have replaced the LCD module with a bank of 7-segment LEDs. What I'll probably try is to fit an EADog 1x8 LCD module in place of the original, with a small micro to handle the display initialization and character translation. The EADog is 55 x 31 x 2 mm, a good fit for the 8050A. This display is actually on a CD unit. Its not been used for some time so may be what you say. Its also on the lower part of the display, perhaps turning the CD upside down, Once I repaired TVs for a back street bodger - a CTV came in with a rainbow pattern on the picture and no amount of degaussing did any good. For some reason I up-ended the TV, the picture improved a lot, so I turned it completely upside down and the picture was perfect. We took the CRT out and put it back upside down, then slackend the yoke clamp and rotated that 180 deg, the purity rings needed a tweak but all was well - so we wedged a lino tile between the anode cap and PCB to stop it cracking over, and cased it up. That reminds me of when people actually rebuilt or replaced picture tubes. Any good stories of tubes imploding? I always made the scrap ones safe by knocking the neck off. I'm aware of one guy that broke a neck off, by accident at a shop, but nothing past that. I've got to check you tube for vidoes of people removing the steel band around a CRT. Not sure how you'd even weasel under one to cut it off, and from a safe distance, but somebody somewhere has to have tried. so it seems the bands are shrink fit into place, and expanded with heat: http://www.patents.com/us-5241393.html pickax to a CRT, indoors. safety equipment is an old blanket: http://www.youtube.com/watch?v=m04XfekeSP4 brick? to a weird "wide" CRT. http://www.youtube.com/watch?v=_0cXW7KQIDQ another stupid one, from the same clever folks: http://www.youtube.com/watch?v=Hx79zJO4zgA |
Bleeding LCD displays
Følgende er skrevet af Phil Hobbs:
When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) Leif -- Husk kørelys bagpå, hvis din bilfabrikant har taget den idiotiske beslutning at undlade det. |
Bleeding LCD displays
"Leif Neland" wrote in message ... Følgende er skrevet af Phil Hobbs: When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) When I was a kid, someone gave me a regen set in a very grand wooden cabinet. When I'd finished breaking it - it was time to take it apart and see what's in it. In a compartment under the one the chassis was in, there was a huge flat profile paper capacitor - one that big could only have been the HT reservoir. Think of all the things I could've got up to with that if I hadn't unraveled it! |
Bleeding LCD displays
Ian Field wrote:
"Leif Neland" wrote in message ... F?lgende er skrevet af Phil Hobbs: When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) When I was a kid, someone gave me a regen set in a very grand wooden cabinet. When I'd finished breaking it - it was time to take it apart and see what's in it. In a compartment under the one the chassis was in, there was a huge flat profile paper capacitor - one that big could only have been the HT reservoir. Think of all the things I could've got up to with that if I hadn't unraveled it! I dragged a huge transformer out of a TV set to grade school once to show people the huge sparks that could be drawn off one winding with a 9 volt battery. It was actually a fairly fat and impressive arc. The transformer was eventually confiscated. Boo. |
Bleeding LCD displays
"Cydrome Leader" wrote in message ... Ian Field wrote: "Leif Neland" wrote in message ... F?lgende er skrevet af Phil Hobbs: When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) When I was a kid, someone gave me a regen set in a very grand wooden cabinet. When I'd finished breaking it - it was time to take it apart and see what's in it. In a compartment under the one the chassis was in, there was a huge flat profile paper capacitor - one that big could only have been the HT reservoir. Think of all the things I could've got up to with that if I hadn't unraveled it! I dragged a huge transformer out of a TV set to grade school once to show people the huge sparks that could be drawn off one winding with a 9 volt battery. It was actually a fairly fat and impressive arc. The transformer was eventually confiscated. Boo. Those old mains derived EHT transformers were probably even more lethal than a MO transformer. For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever had mains derived EHT. |
Bleeding LCD displays
Ian Field wrote:
"Cydrome Leader" wrote in message ... Ian Field wrote: "Leif Neland" wrote in message ... F?lgende er skrevet af Phil Hobbs: When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) When I was a kid, someone gave me a regen set in a very grand wooden cabinet. When I'd finished breaking it - it was time to take it apart and see what's in it. In a compartment under the one the chassis was in, there was a huge flat profile paper capacitor - one that big could only have been the HT reservoir. Think of all the things I could've got up to with that if I hadn't unraveled it! I dragged a huge transformer out of a TV set to grade school once to show people the huge sparks that could be drawn off one winding with a 9 volt battery. It was actually a fairly fat and impressive arc. The transformer was eventually confiscated. Boo. Those old mains derived EHT transformers were probably even more lethal than a MO transformer. For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever had mains derived EHT. It was some sort of large gooped up with tar EI core thingy with one super high inductance winding. I still have no idea how it worked in a television. If they made 6-7kv was there then some sort of diode and cap multiplier to run the CRT? The "oldest" TVs I sort of recall the inside of were Zenith consoles with remanufactured module system with the bizarro rectangular connectors and constantly changing color circuit boards. |
Bleeding LCD displays
Jeff Liebermann wrote:
On Sun, 02 Mar 2014 12:55:11 +0000, N_Cook wrote: Cause and any amelioration, short of draining the liquid and starting again (for elfin safety in nothing else), and of course unobtanium replacement displays Where I used to work a batch of early large LCD display Philips DVM meters for the engineers. Every now and then , despite warning labels, someone would leave one in direct sunlight (UK version) for a while and the display would become next to useless, permanently. Presumably the LC migrates out of its assigned wells and does not go back in them. Anyone know of a localised heat/cold/pressure treatment or something like that ,at least, won't make matters worse , and may actually improve the splodge a bit? LCD panels have a slots at the bottom of the glass to help equalize inside to outside air pressure. If it were sealed shut, your laptop or tablet display would explode at altitude. One of my non-clever mistakes is to clean the screen of a warm running laptop display with a soapy water while in the upright position. As the screen cools, the soapy water is sucked into the panel via the bottom slots. Eventually, LCD leprosy forms along the bottom of the display. I have several panels like that, all from an office where the cleaning service washed down the LCD displays every night as part of the service. I would speculate (which means I haven't tried doing this) that it would be possible to use the partial vacuum effect to replenish the liquid in the display. I have no idea what's in the liquid or where to obtain a supply. Just remove the lower part of the panel frame, heat the panel, dump into some warm LCD liquid, and hope that it sucks the liquid into the panel as it cools. LCD Panel Rejuvenator (patent pending). The LCD panel manufactures could probably prevent the problem by simply adding a foam sponge along the slot to act as a reservoir. Incidentally, the fluid is reputed to be sticky and toxic. it's oily for sure, and busted open LCDs smell bad but that may be from the 5000 layers of adhesive and plastic sheets that make them. Old calculator displays were a bit simpler, but still had a foul smell when smashed up. |
Bleeding LCD displays
"Cydrome Leader" wrote in message ... Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "Leif Neland" wrote in message ... F?lgende er skrevet af Phil Hobbs: When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) When I was a kid, someone gave me a regen set in a very grand wooden cabinet. When I'd finished breaking it - it was time to take it apart and see what's in it. In a compartment under the one the chassis was in, there was a huge flat profile paper capacitor - one that big could only have been the HT reservoir. Think of all the things I could've got up to with that if I hadn't unraveled it! I dragged a huge transformer out of a TV set to grade school once to show people the huge sparks that could be drawn off one winding with a 9 volt battery. It was actually a fairly fat and impressive arc. The transformer was eventually confiscated. Boo. Those old mains derived EHT transformers were probably even more lethal than a MO transformer. For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever had mains derived EHT. It was some sort of large gooped up with tar EI core thingy with one super high inductance winding. I still have no idea how it worked in a television. If they made 6-7kv was there then some sort of diode and cap multiplier to run the CRT? AFAIK it was just half-wave rectified, the peak value whatever that was, ended up at the final anode. Its a bit surprising when you think that generally, CRTs were long narrow defection jobs - some early homebrew sets had electrostatic deflection, maybe a few commercially produced sets too. |
Bleeding LCD displays
Ian Field wrote:
"Cydrome Leader" wrote in message ... Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "Leif Neland" wrote in message ... F?lgende er skrevet af Phil Hobbs: When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) When I was a kid, someone gave me a regen set in a very grand wooden cabinet. When I'd finished breaking it - it was time to take it apart and see what's in it. In a compartment under the one the chassis was in, there was a huge flat profile paper capacitor - one that big could only have been the HT reservoir. Think of all the things I could've got up to with that if I hadn't unraveled it! I dragged a huge transformer out of a TV set to grade school once to show people the huge sparks that could be drawn off one winding with a 9 volt battery. It was actually a fairly fat and impressive arc. The transformer was eventually confiscated. Boo. Those old mains derived EHT transformers were probably even more lethal than a MO transformer. For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever had mains derived EHT. It was some sort of large gooped up with tar EI core thingy with one super high inductance winding. I still have no idea how it worked in a television. If they made 6-7kv was there then some sort of diode and cap multiplier to run the CRT? AFAIK it was just half-wave rectified, the peak value whatever that was, ended up at the final anode. Its a bit surprising when you think that generally, CRTs were long narrow defection jobs - some early homebrew sets had electrostatic deflection, maybe a few commercially produced sets too. Is this why tubes like in oscilloscopes, which are electrocstatic are so long for their screen size? My current scope doesn't have the hump in the back for the end of the tube, but I suspect it's a normal CRT with a yoke and coils as well, since it's really just a small computer monitor. |
Bleeding LCD displays
On 03/07/2014 03:13 PM, Cydrome Leader wrote:
Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "Leif Neland" wrote in message ... F?lgende er skrevet af Phil Hobbs: When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) When I was a kid, someone gave me a regen set in a very grand wooden cabinet. When I'd finished breaking it - it was time to take it apart and see what's in it. In a compartment under the one the chassis was in, there was a huge flat profile paper capacitor - one that big could only have been the HT reservoir. Think of all the things I could've got up to with that if I hadn't unraveled it! I dragged a huge transformer out of a TV set to grade school once to show people the huge sparks that could be drawn off one winding with a 9 volt battery. It was actually a fairly fat and impressive arc. The transformer was eventually confiscated. Boo. Those old mains derived EHT transformers were probably even more lethal than a MO transformer. For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever had mains derived EHT. It was some sort of large gooped up with tar EI core thingy with one super high inductance winding. I still have no idea how it worked in a television. If they made 6-7kv was there then some sort of diode and cap multiplier to run the CRT? AFAIK it was just half-wave rectified, the peak value whatever that was, ended up at the final anode. Its a bit surprising when you think that generally, CRTs were long narrow defection jobs - some early homebrew sets had electrostatic deflection, maybe a few commercially produced sets too. Is this why tubes like in oscilloscopes, which are electrocstatic are so long for their screen size? My current scope doesn't have the hump in the back for the end of the tube, but I suspect it's a normal CRT with a yoke and coils as well, since it's really just a small computer monitor. Electrostatic focusing is much faster than magnetic, but not nearly so well controlled--you get a lot of aberrations, which grow very rapidly with deflection angle. The basic issue is that electrons that are closer to the plate get bent further than those further away. In an optical system, you can correct for this by using a combination of positive and negative lenses, but there's no such thing as a negative electrostatic lens. It was a real parlour trick getting decent vertical linearity and good spot sizes with pure electrostatic deflection. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net |
Bleeding LCD displays
"Phil Hobbs" wrote in message m... On 03/07/2014 03:13 PM, Cydrome Leader wrote: Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "Leif Neland" wrote in message ... F?lgende er skrevet af Phil Hobbs: When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) When I was a kid, someone gave me a regen set in a very grand wooden cabinet. When I'd finished breaking it - it was time to take it apart and see what's in it. In a compartment under the one the chassis was in, there was a huge flat profile paper capacitor - one that big could only have been the HT reservoir. Think of all the things I could've got up to with that if I hadn't unraveled it! I dragged a huge transformer out of a TV set to grade school once to show people the huge sparks that could be drawn off one winding with a 9 volt battery. It was actually a fairly fat and impressive arc. The transformer was eventually confiscated. Boo. Those old mains derived EHT transformers were probably even more lethal than a MO transformer. For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever had mains derived EHT. It was some sort of large gooped up with tar EI core thingy with one super high inductance winding. I still have no idea how it worked in a television. If they made 6-7kv was there then some sort of diode and cap multiplier to run the CRT? AFAIK it was just half-wave rectified, the peak value whatever that was, ended up at the final anode. Its a bit surprising when you think that generally, CRTs were long narrow defection jobs - some early homebrew sets had electrostatic deflection, maybe a few commercially produced sets too. Is this why tubes like in oscilloscopes, which are electrocstatic are so long for their screen size? My current scope doesn't have the hump in the back for the end of the tube, but I suspect it's a normal CRT with a yoke and coils as well, since it's really just a small computer monitor. Electrostatic focusing is much faster than magnetic, but not nearly so well controlled--you get a lot of aberrations, which grow very rapidly with deflection angle. The basic issue is that electrons that are closer to the plate get bent further than those further away. In an optical system, you can correct for this by using a combination of positive and negative lenses, but there's no such thing as a negative electrostatic lens. It was a real parlour trick getting decent vertical linearity and good spot sizes with pure electrostatic deflection. Speaking of optics - I remember a PC monitor with a slightly concave faceplate, that was a pretty substantial slab of glass, the things weighed a bloody ton! Most of the components were house coded so it was frequently neccessary to board-swap from the growing accumulation of scrap units. |
Bleeding LCD displays
Ian Field wrote:
"Phil Hobbs" wrote in message m... On 03/07/2014 03:13 PM, Cydrome Leader wrote: Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "Leif Neland" wrote in message ... F?lgende er skrevet af Phil Hobbs: When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) When I was a kid, someone gave me a regen set in a very grand wooden cabinet. When I'd finished breaking it - it was time to take it apart and see what's in it. In a compartment under the one the chassis was in, there was a huge flat profile paper capacitor - one that big could only have been the HT reservoir. Think of all the things I could've got up to with that if I hadn't unraveled it! I dragged a huge transformer out of a TV set to grade school once to show people the huge sparks that could be drawn off one winding with a 9 volt battery. It was actually a fairly fat and impressive arc. The transformer was eventually confiscated. Boo. Those old mains derived EHT transformers were probably even more lethal than a MO transformer. For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever had mains derived EHT. It was some sort of large gooped up with tar EI core thingy with one super high inductance winding. I still have no idea how it worked in a television. If they made 6-7kv was there then some sort of diode and cap multiplier to run the CRT? AFAIK it was just half-wave rectified, the peak value whatever that was, ended up at the final anode. Its a bit surprising when you think that generally, CRTs were long narrow defection jobs - some early homebrew sets had electrostatic deflection, maybe a few commercially produced sets too. Is this why tubes like in oscilloscopes, which are electrocstatic are so long for their screen size? My current scope doesn't have the hump in the back for the end of the tube, but I suspect it's a normal CRT with a yoke and coils as well, since it's really just a small computer monitor. Electrostatic focusing is much faster than magnetic, but not nearly so well controlled--you get a lot of aberrations, which grow very rapidly with deflection angle. The basic issue is that electrons that are closer to the plate get bent further than those further away. In an optical system, you can correct for this by using a combination of positive and negative lenses, but there's no such thing as a negative electrostatic lens. It was a real parlour trick getting decent vertical linearity and good spot sizes with pure electrostatic deflection. Speaking of optics - I remember a PC monitor with a slightly concave faceplate, that was a pretty substantial slab of glass, the things weighed a bloody ton! Was it possibly one of those Zenith flat CRTs that really did look concave? They were really weird looking, powered on or off. |
Bleeding LCD displays
"Cydrome Leader" wrote in message ...
Ian Field wrote: Speaking of optics - I remember a PC monitor with a slightly concave faceplate, that was a pretty substantial slab of glass, the things weighed a bloody ton! Was it possibly one of those Zenith flat CRTs that really did look concave? They were really weird looking, powered on or off. Zernith made a 14" CRT for computer monitors with a flat face, anticipating Sony by about a decade. (The phosphors were laid down without the mask. The tolerances were so tight, that any mask would work with any faceplate, simply be dropping it into place.) Someone at work had one, and it did, indeed, look odd. Sony compensated for that optical illusion with a faintly bulging screen. I have one of the 400-series WEGAs in my bedroom (it's been going strong since 2000), and you can see the bulge if you stand the screen and look downward. |
Bleeding LCD displays
"Cydrome Leader" wrote in message ... Ian Field wrote: "Phil Hobbs" wrote in message m... On 03/07/2014 03:13 PM, Cydrome Leader wrote: Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: "Leif Neland" wrote in message ... F?lgende er skrevet af Phil Hobbs: When I was a kid, I used to get dead TVs and take them apart for the components. To get rid of the picture tubes, I put them in a Rubbermaid trash can and shot out the faceplate with my slingshot. As a kid I unwrapped the capacitors to find the interesting stuff inside all that wrapping paper. Never found anything, though... :-) When I was a kid, someone gave me a regen set in a very grand wooden cabinet. When I'd finished breaking it - it was time to take it apart and see what's in it. In a compartment under the one the chassis was in, there was a huge flat profile paper capacitor - one that big could only have been the HT reservoir. Think of all the things I could've got up to with that if I hadn't unraveled it! I dragged a huge transformer out of a TV set to grade school once to show people the huge sparks that could be drawn off one winding with a 9 volt battery. It was actually a fairly fat and impressive arc. The transformer was eventually confiscated. Boo. Those old mains derived EHT transformers were probably even more lethal than a MO transformer. For a B&W TV, 6 - 7kV was about average - not sure whether any CTV ever had mains derived EHT. It was some sort of large gooped up with tar EI core thingy with one super high inductance winding. I still have no idea how it worked in a television. If they made 6-7kv was there then some sort of diode and cap multiplier to run the CRT? AFAIK it was just half-wave rectified, the peak value whatever that was, ended up at the final anode. Its a bit surprising when you think that generally, CRTs were long narrow defection jobs - some early homebrew sets had electrostatic deflection, maybe a few commercially produced sets too. Is this why tubes like in oscilloscopes, which are electrocstatic are so long for their screen size? My current scope doesn't have the hump in the back for the end of the tube, but I suspect it's a normal CRT with a yoke and coils as well, since it's really just a small computer monitor. Electrostatic focusing is much faster than magnetic, but not nearly so well controlled--you get a lot of aberrations, which grow very rapidly with deflection angle. The basic issue is that electrons that are closer to the plate get bent further than those further away. In an optical system, you can correct for this by using a combination of positive and negative lenses, but there's no such thing as a negative electrostatic lens. It was a real parlour trick getting decent vertical linearity and good spot sizes with pure electrostatic deflection. Speaking of optics - I remember a PC monitor with a slightly concave faceplate, that was a pretty substantial slab of glass, the things weighed a bloody ton! Was it possibly one of those Zenith flat CRTs that really did look concave? They were really weird looking, powered on or off. Now you mention it I think they were zenith - there was a sort of flurry of people wanting them repaired, then they dried up as if they'd never existed. Not long after that, CRTs in general went out of fashion. I didn't miss those flat screens - they were bloody heavy! |
Bleeding LCD displays
William Sommerwerck wrote:
"Cydrome Leader" wrote in message ... Ian Field wrote: Speaking of optics - I remember a PC monitor with a slightly concave faceplate, that was a pretty substantial slab of glass, the things weighed a bloody ton! Was it possibly one of those Zenith flat CRTs that really did look concave? They were really weird looking, powered on or off. Zernith made a 14" CRT for computer monitors with a flat face, anticipating Sony by about a decade. (The phosphors were laid down without the mask. The tolerances were so tight, that any mask would work with any faceplate, simply be dropping it into place.) Someone at work had one, and it did, indeed, look odd. Sony compensated for that optical illusion with a faintly bulging screen. I have one of the 400-series WEGAs in my bedroom (it's been going strong since 2000), and you can see the bulge if you stand the screen and look downward. The monitor wars from back then were amusing. Getting my first 15" monitor was a big deal, and they even had strange stuff like 16" monitors (Nanao made those). Quite a few of the Taiwanese computer monitors were actually pretty good as well. Once they really nailed good displays for computers, the cheap and crappy LCDs flooded the market. I'm typing up this message on a Dell badged Sony Trinitron made in Sep, 2000. The retrace lines are appearing so it's time for some new caps at some point. |
Bleeding LCD displays
"Cydrome Leader" wrote in message ... William Sommerwerck wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: Speaking of optics - I remember a PC monitor with a slightly concave faceplate, that was a pretty substantial slab of glass, the things weighed a bloody ton! Was it possibly one of those Zenith flat CRTs that really did look concave? They were really weird looking, powered on or off. Zernith made a 14" CRT for computer monitors with a flat face, anticipating Sony by about a decade. (The phosphors were laid down without the mask. The tolerances were so tight, that any mask would work with any faceplate, simply be dropping it into place.) Someone at work had one, and it did, indeed, look odd. Sony compensated for that optical illusion with a faintly bulging screen. I have one of the 400-series WEGAs in my bedroom (it's been going strong since 2000), and you can see the bulge if you stand the screen and look downward. The monitor wars from back then were amusing. Getting my first 15" monitor was a big deal, and they even had strange stuff like 16" monitors (Nanao made those). Quite a few of the Taiwanese computer monitors were actually pretty good as well. Once they really nailed good displays for computers, the cheap and crappy LCDs flooded the market. I'm typing up this message on a Dell badged Sony Trinitron made in Sep, 2000. The retrace lines are appearing so it's time for some new caps at some point. Somewhere in the back of the garage I have about 8 CPD15s (some badged as Dell). Since finding an analogue LCD TV with a VGA socket on the back in the bin room at the flats, the Sonys haven't got any nearer to being dragged inside and repaired. |
Bleeding LCD displays
Ian Field wrote:
"Cydrome Leader" wrote in message ... William Sommerwerck wrote: "Cydrome Leader" wrote in message ... Ian Field wrote: Speaking of optics - I remember a PC monitor with a slightly concave faceplate, that was a pretty substantial slab of glass, the things weighed a bloody ton! Was it possibly one of those Zenith flat CRTs that really did look concave? They were really weird looking, powered on or off. Zernith made a 14" CRT for computer monitors with a flat face, anticipating Sony by about a decade. (The phosphors were laid down without the mask. The tolerances were so tight, that any mask would work with any faceplate, simply be dropping it into place.) Someone at work had one, and it did, indeed, look odd. Sony compensated for that optical illusion with a faintly bulging screen. I have one of the 400-series WEGAs in my bedroom (it's been going strong since 2000), and you can see the bulge if you stand the screen and look downward. The monitor wars from back then were amusing. Getting my first 15" monitor was a big deal, and they even had strange stuff like 16" monitors (Nanao made those). Quite a few of the Taiwanese computer monitors were actually pretty good as well. Once they really nailed good displays for computers, the cheap and crappy LCDs flooded the market. I'm typing up this message on a Dell badged Sony Trinitron made in Sep, 2000. The retrace lines are appearing so it's time for some new caps at some point. Somewhere in the back of the garage I have about 8 CPD15s (some badged as Dell). Since finding an analogue LCD TV with a VGA socket on the back in the bin room at the flats, the Sonys haven't got any nearer to being dragged inside and repaired. I can't bring myself to tossing my monitor mountain, and most still work fine (that's why they are still here.) |
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