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Discussion Starter #1
Hi, I'm Neal, and just registered. I've been reading and using this forum for a while. I have a Toshiba __HX81 set that blew its convergence amps after 5 years of faithful service. I've used everything here to twice replace the amps, and each time the fix lasted about 2 weeks. Note that each time I've lifted one end of each of the power resistors and checked them, and afterward the touch focus error always cleared up and life was grand (for a couple of weeks.)

This time around I'm going to try running the set without the amps and checking the power supply pins as suggested. anything else I should look at as 'root cause' of the failures? Given I've used premium thermal goop I don't think it is a cooling issue.

1st 2 failures - set worked but touch focus errors
3rd failure - blinking red light/led

thanks!
nrf
 

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Your thread was moved to the proper forum for your set.

Repeat failures can be caused by:
1) quality of parts - what supplier did you use?
2) choice of parts - which chips did you buy?
3) open connections or resistors - did you resolder the numerous ring cracks on the board?
4) dc offset on the inputs to the convergence amps
5) to much or too little heat sink compound
6) power supply problems
7) convergence yoke bad - is it the same channel that causes problems?
8) too much edge correction or any number of other problems
 
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thanks, plenty to chew on there. are cracked PC conductors common? would they uncrack for 2 weeks then suddenly crack? likewise with opens. not really channel dependent as TF failed on component inputs for example. having replaced multiple cpu/hs combo so know how to do thermal, first case used arctic silver and a sanyo part with the dimpled logo.. I guess I will remove amps and look at dc offset, power supply voltage. Beyond that I suspect it is beyond my abilities.

thanks!
nrf
 

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Cracks are very common. They can be fine one moment and have enough resistance the next to cause a problem. Temperature changes, humidity, and luck can affect these kinds of problems.

One should always scan the surrounding circuits and resolder any connection that even remotely looks like it might be cracked, powdery, or otherwise suspicious.
 
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