Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #11   Report Post  
Old March 3rd 14, 01:44 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Apr 2008
Posts: 5,188
Default 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

  #12   Report Post  
Old March 3rd 14, 07:04 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Oct 2010
Posts: 1,405
Default 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.

  #13   Report Post  
Old March 3rd 14, 07:12 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Oct 2010
Posts: 1,405
Default 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.

  #14   Report Post  
Old March 3rd 14, 07:16 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Oct 2010
Posts: 1,405
Default 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.

  #15   Report Post  
Old March 3rd 14, 08:04 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jul 2006
Posts: 826
Default 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."


  #16   Report Post  
Old March 3rd 14, 08:59 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Oct 2010
Posts: 1,405
Default 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.

  #17   Report Post  
Old March 3rd 14, 11:12 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jul 2006
Posts: 1,832
Default 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?
  #18   Report Post  
Old March 4th 14, 09:30 AM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Apr 2008
Posts: 5,188
Default 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
  #19   Report Post  
Old March 4th 14, 05:12 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Oct 2010
Posts: 1,405
Default 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.

  #20   Report Post  
Old March 4th 14, 05:40 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jul 2006
Posts: 1,832
Default 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.




Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Very early LCD displays N_Cook Electronics Repair 3 September 15th 09 02:17 PM
Re-using laptop displays.... Michael Black Electronics Repair 1 December 30th 06 05:10 AM
Re-using laptop displays.... Malissa Baldwin Electronics Repair 0 December 29th 06 03:17 AM
Re-using laptop displays.... Rüdiger Electronics Repair 1 December 28th 06 04:39 AM
Anyone know how to get replacement LCD displays Barry & Nikki Electronics Repair 2 January 19th 05 09:54 AM


All times are GMT +1. The time now is 12:38 AM.

Powered by vBulletin® Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright ©2004-2020 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"

 

Copyright © 2017