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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. |
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#1
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i know not really electronic repair but i could find no other
suitable group. I have two big color spots/circles (3" diameter) on the TV/CRT with a big bright stripe between the two spots put there by a 3/4" x 3/4" cylinder (? hematite ? it is strong ?) type magnet, the cylinder version of these http://www.kjmagnetics.com/proddetail.asp?prod=MT%2DM is there a best way to repair ? how ? helpful replies appreciated. robb |
#2
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On Fri, 14 Aug 2009 15:32:55 -0400, "robb" wrote:
i know not really electronic repair but i could find no other suitable group. I have two big color spots/circles (3" diameter) on the TV/CRT with a big bright stripe between the two spots put there by a 3/4" x 3/4" cylinder (? hematite ? it is strong ?) type magnet, the cylinder version of these http://www.kjmagnetics.com/proddetail.asp?prod=MT%2DM is there a best way to repair ? how ? You might recover the display just with a few on/off cycles. Many (most? all?) modern CRTs include a degauss cycle on power-up. Sam Goldwasser's Repair FAQ is probably the best summary of the manual method if the set doesn't cure itself: http://www.repairfaq.org/samnew/tvfaq/tvdegacrt.htm Bookmark the parent page. Lots of good dope. helpful replies appreciated. Always an optimist, eh? ;-) -- Rich Webb Norfolk, VA |
#3
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![]() "Rich Webb" wrote in message ... On Fri, 14 Aug 2009 15:32:55 -0400, "robb" wrote: I have two big color spots/circles (3" diameter) on the TV/CRT with a big bright stripe between the two spots put there by a 3/4" x 3/4" cylinder (? hematite ? it is strong ?) type magnet, the cylinder version of these is there a best way to repair ? how ? You might recover the display just with a few on/off cycles. Many (most? all?) modern CRTs include a degauss cycle on power-up. Sam Goldwasser's Repair FAQ is probably the best summary of the manual method if the set doesn't cure itself: http://www.repairfaq.org/samnew/tvfaq/tvdegacrt.htm Bookmark the parent page. Lots of good dope. helpful replies appreciated. Always an optimist, eh? ;-) Yes. thanks Rich, for the info and help. The color spots improved with the 20 minutes off/on but the bright flaring bar between the dots did not. I started with weaker magnets. I tried moving them in front of the bar in/out every which way with only minor changes. I put the original offending magnet in a fist and waved it about the same way. While brushing fist by the screen diagonally/chaotically across the bar seemed to have the most desired result. The spots are gone and slight remnant of the bar. Thanks again, robb |
#4
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i know not really electronic repair but i could find no other
suitable group. I have two big color spots/circles (3" diameter) on the TV/CRT with a big bright stripe between the two spots put there by a 3/4" x 3/4" cylinder (? hematite ? it is strong ?) type magnet, the cylinder version of these http://www.kjmagnetics.com/proddetail.asp?prod=MT%2DM is there a best way to repair ? how ? Google for "CRT degaussing". If you're lucky, proper application of a degaussing coil will remove the residual magnetization which has been left in the CRT's shadow mask/lines by the small magnets, and will restore proper color on the screen. If you are *un*lucky, the little magnets are so strong that they actually attracted and bent the shadow mask/wires when they were held up to the front of the CRT. If this has happened, degaussing probably won't eliminate the discoloration - I don't know of a remedy other than replacing the CRT itself. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#5
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If you are *un*lucky, the little magnets are so strong that they
actually attracted and bent the shadow mask/wires when they were held up to the front of the CRT. If this has happened, degaussing probably won't eliminate the discoloration -- I don't know of a remedy other than replacing the CRT itself. There is a solution, which was discussed not long ago in this group. My Sony WEGA had this problem, caused when I (deliberately) turned off a bulk tape eraser near the CRT. The splotch lasted for years, but disappeared "spontaneously" when the set was moved to my bedroom in March. The solution is simple -- "bang" the set gently. |
#6
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On Fri, 14 Aug 2009 15:46:07 -0700, William Sommerwerck wrote:
If you are *un*lucky, the little magnets are so strong that they actually attracted and bent the shadow mask/wires when they were held up to the front of the CRT. If this has happened, degaussing probably won't eliminate the discoloration -- I don't know of a remedy other than replacing the CRT itself. There is a solution, which was discussed not long ago in this group. My Sony WEGA had this problem, caused when I (deliberately) turned off a bulk tape eraser near the CRT. The splotch lasted for years, but disappeared "spontaneously" when the set was moved to my bedroom in March. Silly sod. All you had to do to reverse it was place the bulk tape eraser 10' away from the tv, turn it on, approach the tv to the distance you had it before, wave it around then BACK AWAY TO 10' while waving it around before turning it off. |
#7
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"AZ Nomad" wrote in message
... On Fri, 14 Aug 2009 15:46:07 -0700, William Sommerwerck wrote: If you are *un*lucky, the little magnets are so strong that they actually attracted and bent the shadow mask/wires when they were held up to the front of the CRT. If this has happened, degaussing probably won't eliminate the discoloration -- I don't know of a remedy other than replacing the CRT itself. There is a solution, which was discussed not long ago in this group. My Sony WEGA had this problem, caused when I (deliberately) turned off a bulk tape eraser near the CRT. The splotch lasted for years, but disappeared "spontaneously" when the set was moved to my bedroom in March. Silly sod. All you had to do to reverse it was place the bulk tape eraser 10' away from the TV, turn it on, approach the TV to the distance you had it before, wave it around then BACK AWAY TO 10' while waving it around before turning it off. You obviously didn't see the discussion. I've been servicing electronic equipment for 50 years, and know how to use a degausser. This was not a case of magnetization, but a case of tangled Trinitron grille wires. All the demagnetizing will not fix the problem. A mechanical jarring is needed. One person told us of the man on the Trinitron production line who banged the CRTs with a rubber mallet as they passed. |
#8
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If the problem is magnetic and not physical, you can (as was mentioned)
use a bulk tape eraser as a makeshift degaussing coil. If you can't find one of those, you can use other electromagnetic devices that are powered by alternating current (AC, not DC). I've used 200 watt soldering pistols to good effect, engraving tools to less-but-still-workable effect, and a cheap aquarium air pump once that almost worked a little bit. Activate the electromagnetic device, bring it close to the discolored spot, and hope it starts looking rather psychedelic - that means it's working... Then gradually draw the device away from the CRT until it no longer has any visible effect, and then turn the device off. This process should demagnetize the part of the CRT that was affected by the magnet. You might have to do it several times, especially with low-power electromagnetic devices... like aquarium pumps. Don't turn the device off while it is near enough to affect the CRT. The result will be colorful, but you will have to do it all over again. The discoloration may fade in time, as most CRT based TV's have a weak degaussing coil built in, (as was mentioned earlier) which activates for a few seconds each time the power is turned on. Have fun with it... Karl |
#9
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On Fri, 14 Aug 2009 16:25:26 -0700, William Sommerwerck wrote:
"AZ Nomad" wrote in message ... On Fri, 14 Aug 2009 15:46:07 -0700, William Sommerwerck wrote: If you are *un*lucky, the little magnets are so strong that they actually attracted and bent the shadow mask/wires when they were held up to the front of the CRT. If this has happened, degaussing probably won't eliminate the discoloration -- I don't know of a remedy other than replacing the CRT itself. There is a solution, which was discussed not long ago in this group. My Sony WEGA had this problem, caused when I (deliberately) turned off a bulk tape eraser near the CRT. The splotch lasted for years, but disappeared "spontaneously" when the set was moved to my bedroom in March. Silly sod. All you had to do to reverse it was place the bulk tape eraser 10' away from the TV, turn it on, approach the TV to the distance you had it before, wave it around then BACK AWAY TO 10' while waving it around before turning it off. You obviously didn't see the discussion. I've been servicing electronic equipment for 50 years, and know how to use a degausser. This was not a case of magnetization, but a case of tangled Trinitron grille wires. All the demagnetizing will not fix the problem. A mechanical jarring is needed. One person told us of the man on the Trinitron production line who banged the CRTs with a rubber mallet as they passed. ooops |
#10
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On Fri, 14 Aug 2009 16:25:26 -0700, "William Sommerwerck"
wrote: "AZ Nomad" wrote in message ... On Fri, 14 Aug 2009 15:46:07 -0700, William Sommerwerck wrote: If you are *un*lucky, the little magnets are so strong that they actually attracted and bent the shadow mask/wires when they were held up to the front of the CRT. If this has happened, degaussing probably won't eliminate the discoloration -- I don't know of a remedy other than replacing the CRT itself. There is a solution, which was discussed not long ago in this group. My Sony WEGA had this problem, caused when I (deliberately) turned off a bulk tape eraser near the CRT. The splotch lasted for years, but disappeared "spontaneously" when the set was moved to my bedroom in March. Silly sod. All you had to do to reverse it was place the bulk tape eraser 10' away from the TV, turn it on, approach the TV to the distance you had it before, wave it around then BACK AWAY TO 10' while waving it around before turning it off. You obviously didn't see the discussion. I've been servicing electronic equipment for 50 years, and know how to use a degausser. This was not a case of magnetization, but a case of tangled Trinitron grille wires. All the demagnetizing will not fix the problem. A mechanical jarring is needed. One person told us of the man on the Trinitron production line who banged the CRTs with a rubber mallet as they passed. yes, try to use the rubber mallet. It should work if the wires are not too messed up. |
#11
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![]() "Dave Platt" wrote in message ... i know not really electronic repair but i could find no other suitable group. I have two big color spots/circles (3" diameter) on the TV/CRT with a big bright stripe between the two spots put there by a 3/4" x 3/4" cylinder (? hematite ? it is strong ?) type magnet, the cylinder version of these http://www.kjmagnetics.com/proddetail.asp?prod=MT%2DM is there a best way to repair ? how ? Google for "CRT degaussing". If you're lucky, proper application of a degaussing coil will remove the residual magnetization which has been left in the CRT's shadow mask/lines by the small magnets, and will restore proper color on the screen. If you are *un*lucky, the little magnets are so strong that they actually attracted and bent the shadow mask/wires when they were held up to the front of the CRT. If this has happened, degaussing probably won't eliminate the discoloration - I don't know of a remedy other than replacing the CRT itself. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Thanks Dave, That seems to be what possibly happened. The degausing part seemed to help some of the problem but the rest was remedied (? perhaps luckily ?) by waving the original magnet diagonally across the screen and problem area. Thanks again. robb |
#12
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"robb" wrote in message
m... I have two big color spots/circles (3" diameter) on the TV/CRT with a big bright stripe between the two spots put there by a 3/4" x 3/4" cylinder type magnet, is there a best way to repair ? how ? thanks to all that sent helpful replies. robb |
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