![]() |
|
#24
|
||||
|
||||
|
FIXED!
(Yes, I'm reviving this old thread, it's working now so no need to start a new one to close this out). Gotta love it when college, career, and family get in the way of important things like reviving old televisions, eh? I finally got bored enough this winter and I have more experience now with troubleshooting electronics so figured I'd see what I could find out. Turns you your suspicions were correct, I missed the obvious: C423, a 470 uF cap in the main 25V feed to the B+ regulator, had completely vented and dribbled its guts all over the board; not sure how I missed that originally. It is marked a safety part in the service manual so I changed it and immediately the TV would turn on and work, though occasionally would still shut down on its own. Further poking around discovered that C443, a 390 pF cap in the horizonal drive circuit was cut out and missing (leads were still in the board, also marked a safety part), and the B+ was hovering around 134V instead of the specified 127V. Someone was clearly in here so I wonder if they fiddled with the B+ setting and bumped it up too high. Or it drifted over the years. Fortunately, on this set it's adjustable so I got it right on 127V now. I installed a new 390 pF cap too. Finally, I reflowed multiple cracked solder joints on the buttons/LED board which restored the LED display functionality. The tines that hold the board in place inside the TV pull hard when one removes the board so that must have happened one too many times. Got it all back together, checked the picture with my BK 1257 and found it to have perfect linearity and convergence. Ran it for over an hour with zero faults. It has a very picture so will be a keeper. So all good now, thanks for helping me get started on this all those years ago! A 13-year repair job isn't too bad for a then-beginner, right?
|
|
|