I screwed up! K4600 Dead

beerbarrel

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I recapped a working 4600. It let a little smoke out and blew the fuse on my iso transformer. Replaced fuse and now monitor is dead. Looked back at the cap job and found C617 in backwards. I reversed that and tried to find what I burnt up in the monitor to kill it. I followed Fromm's flowchart but it is no help. TR501 and 502 are good. C608 is good. I subbed the power board into a working 4600 and it is OK. I also subbed the other boards and they are good. I know that the problem is on the mainboard somewhere but I can't seem to track it down. Any ideas would be appreciated.

Tracy
 
I agree Ken. It did check good on my ESR tester though. I have the monitor working now but still have problems. I only had 110 volts at the blue lead of the power transistor on the power interface card. Swapped power cards from a good monitor and the had 170 volts and the Hula. I swapped horizontal cards and had normal voltage 128 at power card. Everything good now but I have no green. That leads to my next question. All transistors check good on video card. I swap in a known good card and get all my colors but the screen rolls with that card and it won't stop. The card is I swapped in is physically different.. It had two pots on it. One for black level and one for horizontal (something or other) can't read the rest. #1 should the different card work? and #2 what could be wrong with my other video card. Could it be that the neck card is not made to work with this video card?

Tracy
 
Not trying to be a smartypants, but is buying a new monitor an option? Might be less headache and a better picture without burn in, when your done.

Tom ,
 
I think I found my color problem. So, it seems that the schematics are not too accurate. I'm looking at the red drive circuit for a problem when the problem is green. If the schematics were right, I would have been looking at the right circuit.TR206 on the video card is bad. According to the schematic that is Red....but it is green if I trace it down on the monitor. It looks like a general purpose PNP...is this correct?
 
According to the charts I have here, TR206 is related to red. (Fromm's flowcharts).

Those transistors (TR204, TR205, and TR206) are replaceable with NTE159, according to a cross reference search.

EDIT: But, yes... they are PNP
 
Scucci,

That is exactly what my chart says. I replaced the transistor in doubt and had a fantastic picture for a few minutes. Then the colors went missing again. Pulled the card and two more transistors for other colors were bad. I replaced them and they failed again. I have to figure out where my short is.

Tracy
 
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