Sony Trinitron (KV-20FV12) Vertical Deflection Stopped

[motorahead]

Re: Sony Trinitron (KV-20FV12) Vertical Deflection Stopped

Makes sense about the possiblity of a misleading error code.

I powered on the TV while checking the 200v pin 6 on CN706. 182.5v was measured until the TV shuts off. Unplugged the connection and the TV still shut off. Voltage at CN502 (source connection for CN706) was the same. However, with CN502/CN706 disconnected. Pin 6 voltage at CN502 is measuring 194.2v. Hope that makes sense.

It's almost a 10v drop when the CN706 is connected. Is that normal?

I also checked pin1 +12v across CN502/CN706. 13.9v connected / 14.04v disconnected.

Lastly for this evening, it's a little awkward powering on the TV while holding the multimeter lead to the board... I screwed up and accidentally shorted pin1 (+12v) with pin2 (-15v) on CN706. There was a pop and a tiny bit of smoke from that area. The TV is behaving the same (at least it's not doing something different?). I don't smell anything and visual inspection of the CB board looks ok.

[motorahead]

Re: Sony Trinitron (KV-20FV12) Vertical Deflection Stopped

Check if the 200v comes up on CN706 pin 6, If it seems low, disconnect CN706 from the cb board and see if the tv stays on.

R_J, I'm wondering if the 182v reading at startup might indicate a bad capacitor somewhere?

[motorahead]

Re: Sony Trinitron (KV-20FV12) Vertical Deflection Stopped

Hi all, just following up on this. Hoping to get the TV off the bench sooner than later.

I may resort to replacing the capacitors on the vertical circuit as well as the IC702.

That 182v reading (200v spec) seems low but not sure what the threshold is for something like this. And if it is unacceptably low, why. Is it the flyback transformer supplying that voltage?

[motorahead]

Hi all, I finally got the TV off the workbench!

I was able to find the service "training manual" (https://www.manualslib.com/manual/92...page=26#manual) on the unit and came across the troubleshooting matrix mentioning the following symptoms which was exactly what my set was doing:

Timer LED: 4 flashes
Relay Clicks: 4 clicks - Power ON, Degauss ON and OFF and Shutdown

It mentioned the IC604 5volt regulator being suspect on the A board. I immediately checked it and observed proper supply voltage, but no 5v on the output. So I ordered a replacement from Digikey (https://www.digikey.com/en/products/...M7805FA/805763) and swapped it out.

That did the trick!

Thanks for all of the help. I intend on keep this TV long term so if something else goes wrong, I'll at least know my way around it.