Captains Log K7203 c009 High b+ squealing

jjhudgins

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Location
Mccalla, Alabama
Patient: K7203
Symptoms:
1. High b+ 139 and not 121. Couldn't adjust down far enough.

2.Squealing / High pitch sound

Solution: replaced cap c009 22uf. Caps on these usually fix a lot of issues but just replacing c009 fixes the noise and the b+. I was able to adjust b+ enough once I replaced c009 So a bad c009 caused high b+ which caused the noise.

several caps were bad, however C009 was the very first one I tried

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Nice catch. Amazing how often one little cap like C009 can throw the whole thing off. Good reminder to always start there on these.
 
Took 2 hours to do. Take your time so you don't lift any traces.

Ready to go and for sale after burn in period.
 
Took 2 hours to do. Take your time so you don't lift any traces.

Ready to go and for sale after burn in period.
I've finally got the magic potion right with those. I think I ran out of them at work but I have a 13" K7203 that I could do a cap demonstration with someday.

also the wisdom of Randy Fromm suggests it can be one of the smallest caps on the board. lol

I had one with an obnoxious squeal, it wound up being one of the plugs to the neckboard needed to be resoldered. (the stationary one on the deflection board side)
 
It's always the small
Things that cause the biggest headaches
problem I had with a V2000 constantly nuking the pre-drive and drive transistors was like a 1 uf cap I didn't realize was domed and bad. for years. lol
 
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