4900 Cap Kit Gone Bad

YellowDog

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Donor 2011, 2013
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Did a cap kit on a 4900 a couple of days ago. Picture (minus screen burn) was perfect. Today I fired it up and the red was starting to bleed. Tuned up the red ajust and the red cutoff and it was fine. I decided to leave it on for a while to see and I just checked it. The colors have gone almost white and I turned the intensity all the way down to no avail.

Could I have gotten some bad caps, they were some brand I had never heard of. If so any hints on which ones to replace or is this monitor toast?

This is what it looks like now. That is a MS Pacman freeplay attract mode playing, in case you didn't recognize it.


ken
 

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What happens when you turn the brightness on the fly down?

You adjusted the "black level" and the "screen" controls?

The brightness (screen) is all the way down & the black level was adjusted to the middle of the range.

B+ was measured at +133V.

This started a couple of hours after the cap kit, so that why I was suspecting a bad cap or one that went bad.

ken
 
On the input board is a transistor and zener diode for "blanking"... if the transistor and zener short you'll get a white screen like that.

RJ
 
Thanks RJ. I'll look at that when I pull it. If I can get replacements, I'll just replace them.

I have the previous 4900 chassis from this monitor. If I have the caps, I'll recap the old one and see if that works better. I have a couple of 4600 cap kits that I can steal caps from.

Update: I just checked the cross reference and there aren't many that I can steal. Oh well, I guess a trip to Fry's tomorrow :(

ken
 
First, if you have a rejuvenator, check the tube. You might have had an internal short lock the screen voltage high....
 
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