19K7000 - intermittent HV shutdown

87 t-66

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I am having an issue with a green WG 19k7000 where it will randomly go into HV shutdown. Sometimes it will happen a few seconds after powering it up. Sometimes it will run for around an hour and then shut down. The b+ is measuring 150-160vdc at both Q11 and R391 when it shuts down.

So far I have:

not found any cold solder/broken traces
new flyback
new cap kit
replaced IC4
replaced R101 - the original was out of spec
replaced Q10
replaced IC2
metered other resistors in the area and could not find any out of spec/shorted/open

Any suggestions of where to go next would be appreciated. I have a few spare chassis that I can use components from. Thanks.
 
I am having an issue with a green WG 19k7000 where it will randomly go into HV shutdown. Sometimes it will happen a few seconds after powering it up. Sometimes it will run for around an hour and then shut down. The b+ is measuring 150-160vdc at both Q11 and R391 when it shuts down.

So far I have:

not found any cold solder/broken traces
new flyback
new cap kit
replaced IC4
replaced R101 - the original was out of spec
replaced Q10
replaced IC2
metered other resistors in the area and could not find any out of spec/shorted/open

Any suggestions of where to go next would be appreciated. I have a few spare chassis that I can use components from. Thanks.

my first guess would be cracks around the flyback area or your ic4 is failing.
 
replace VR8.

once in a while the glue will pop the pot loose inside or it will degrade it.

i have them in stock if you need one.

Peace
Buffett
 
my first guess would be cracks around the flyback area or your ic4 is failing.
the flyback area looks good, IC4 has been replaced.

replace VR8.

once in a while the glue will pop the pot loose inside or it will degrade it.

i have them in stock if you need one.

Peace
Buffett

I have one that I can swap it with. The replacement still has glue on it from the factory. Should I make sure that it's adjusted to any certain resistance? Or just leave it as-is?
 
if its still glued to factory setting it should be fine to leave it there for testing.
 
any of those pots that have glue on them are subject to the same issue.

it is better to replace it.

Peace
Buffett
 
Thanks. I just replaced it. Will leave the game on for a bit to see what happens.


if you need a new VR8 pot i have plenty in stock just pm me because i don't have those on my site yet.
 
I've had it on for 3 hours and it hasn't shut down again. I don't think it went over an hour before. I'll leave it on for a few hours tomorrow and cross my fingers that it is good to go. Thanks for the help. Will report back tomorrow.
 
I left it on a couple hours again yesterday and it didnt shut off. Looks like it was the pot. Thanks again for the help!
 
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