Need Help K7000 Fades to black after 20 Min

sconfu

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Have a P447 k7000 series that has all but the 3 (C4,5,6) caps not offered in bobs kit replaced.

Goes from perfect to black in about 20 seconds after about 20 min.

Had problem before and after cap install

so looked it over good a couple questionable joints re-flowed still goes black.


So where do I start to troubleshoot?

http://arcarc.xmission.com/PDF_Monitors/Wells Gardner K7000 Schematic.pdf

start with R21-29?
2N3904?

Will checking voltage at the brightness pot before and after the problem tell me anything?

any help is appreciated

-Brian
 
Does your flyback have tiny little cracks around the brightness pot?
 
are you talking at the base of the flyback, didnt see anything like a blown flyback looks like

As I said "brightness pot". There is a screen control potentiometer on the flyback that controls the brightness on the screen. the original K7000 flyback typically develops hairline cracks around both the focus and brightness pots. Sometimes, this can affect their function....
 
As I said "brightness pot". There is a screen control potentiometer on the flyback that controls the brightness on the screen. the original K7000 flyback typically develops hairline cracks around both the focus and brightness pots. Sometimes, this can affect their function....

ok sorry i understand now its late and im still celebrating the Saints victory if you know what i mean

But sadly the Flyback looks good no cracks

the cab was in a Chinese restaurant all of its life and now the whole inside has a layer of stir fry grease and reaks of burnt crab ragoon
 
Props and +Rep to Modessitt

The flyback has a hairline crack that i missed

You the man
 
So have you replaced the flyback yet ?

There's solder joints on the neckboard that will cause the same symptom.
Did you check that too?
 
Ordered a new HV from bob theres a crack across the bright adjust so I will let you know what happens

Messed with it a bit today and after 5 min it goes almost all the way dark then comes back then goes away a few times before going dark and staying that way till its cooled off.
 
crossing my fingers too... either that or theres cold solder someplace else.... im pulling for ya sconfu


if not, where in il are you? if your up north we could try another chassis from my k7000 tub lol
 
crossing my fingers too... either that or theres cold solder someplace else.... im pulling for ya sconfu


if not, where in il are you? if your up north we could try another chassis from my k7000 tub lol

30 Min East of St louis, a world away from Chicagoland

If it is a cold joint is it enough to heat it up or do I need to wick all the solder, clean with Alcohol, and start over?
 
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