Quote:
Originally Posted by bandersen
Seems pretty likely there's a problem in the vertical amp. V13 gets it's plate voltage from the junction of R57/58. Check C77, R99, R100, R102, R103 etc.
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Bob,
I carefully checked the plate voltage for V13. I was only getting 12 volts instead of the 235 volts shown in the voltage table. I was only getting 257 volts on pin 6 of V13 instead of the 470 volts listed.
There was no change after substituting C77 and C80. That most likely left the HV caps C81 and C82. C81 was substituted with no change. However the C82 substitution caused the voltages to get very close to the voltage chart. Pin 3 was at 281 volts and pin 6 was at 472 volts.
With the picture adjusted with the Vert. Height and the Vert. Centering controls, it looks pretty good. There is just a hint of foldback at the very top of the picture. It is a little brighter the last 1/32 to 1/16 inch. Over all, pretty good.
However the HV module still refuses to supply more than 3900-4200 volts to the receiver. I'm beginning to think that it is just not capable of doing so. I'm asking those who have used this module on their 50-T702 to confirm that they get 4800 volts delivered to the CRT.
I have some cleaning up of the chassis after all that trouble shooting.
Thanks Bob for taking the time to help me with this problem. It wasn't too many months ago that I did a complete recap and resistor change on this thing. Your help is appreciated. Thank you.