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Flyback replacement advice for LG 29" crt TV

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freefall80

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I got that set (RT-29FB75VE) in a very good condition with a great picture

it worked fine for about 8 month then the FBT arced out due to a tiny hole discovered int it

I sealed it with silicon sealant and worked fine again for a weak (about 70~80 hours) then the fbt is making a clicking spark sound from another point
with no picture ofcourse and the power led is on/off along with that clicking sound (similar to the reply sound) about 1 sec interval

I could not see a ***** or another hole but I sealed that area too with a larger patch but no matter what the problem is still there

I am afraid if I replaced the fbt the problem will come again, perhaps another component is failing the fbt? I was thinking that the original fix will last much longer, but there is no continious arcing anymore, that clicking sparky sound is different than the very first arcing issue

any help will be appreciated

Thanks
 

BradtheRad

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I assume you can open up the housing. See if the arcing is visible in a dark room. Watch closely amidst dust at the high voltage circuitry.
It may let you locate the spark, in case it's from a faulty component which can be fixed or replaced.
 

freefall80

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I assume you can open up the housing. See if the arcing is visible in a dark room. Watch closely amidst dust at the high voltage circuitry.
It may let you locate the spark, in case it's from a faulty component which can be fixed or replaced.
yes sure the housing is opened and I can see the spark (not arcing) but is kinda visible through the sealing!! there is no ***** or hole that you can see

it is like a relay sound with a spark (on/off)

is that normal? why it is not arcing like last time?

is that a short inside the FBT?

thanks for your reply
 

betwixt

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Unfortunately, the heat from the original spark will carbonize the plastic insulation and create it's own discharge path. There is no cure, you will have to replace the transformer. It will gradually get worse and start damaging other components I'm afraid.

You should be able to buy a replacement and swap it with the original but beware of the high voltage on the CRT which could give a nasty shock even after several days of being switched off.

Brian.
 

freefall80

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Unfortunately, the heat from the original spark will carbonize the plastic insulation and create it's own discharge path. There is no cure, you will have to replace the transformer. It will gradually get worse and start damaging other components I'm afraid.

You should be able to buy a replacement and swap it with the original but beware of the high voltage on the CRT which could give a nasty shock even after several days of being switched off.

Brian.
Thanks Bryan
I was watching the TV for a weak with a great picture with the first silicon fix and then that new fault happened, the replacement is about 1/4 the price of the whole set, I would still like to fix it but do you think that it is only that FBT?
I dont see any sign of other component failure visually on the board

one more question : would raising up the gain of the 3 main colors from the service menu help damage or shorten the life of parts in the set?

thanks
 

betwixt

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Almost certainly the FBT is the only faulty part but there is a high risk of the flash-over causing damage elsewhere and the extra strain on the horizontal output transistor damaging it.

Raising the gain won't have any effect on parts life but it will make the picture worse. There is a correct setting and any change from it will upset the tracking of the three colors. Why do you want to change it?

Brian.
 

freefall80

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I asked about raising the gain because that is the only thing I made before 2 or 3 months of the very first failure

I just raised it slightly, perhaps 10% more than the original settings
there is no sign of any visual issues for the picture

for such a great picture I am really surprised that FBT failed too soon?

sorry but what do you mean by "flash-over"

as soon as the tv failed I turned it off, and I did turn it on about 4-5 times again after resealing the FBT which did not help
I have also video recorded that fault if you care I can upload on youtube for you to see
I also did short test the legs of the FBT while it is on the board still and found many legs shorted together, I dont know what is the normal but just thought to tell that
 

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