Panasonic TX-32LM70 power supply issue
Good day folks. I'm having a bit of trouble with this Panasonic telly that doesn't want to be fixed 
It has a hard time starting, requiring multiple attempts before finally staying on and sometimes displays a mess of lines and colors. I thought it was the main board, but then noticed the backlight was flickering too and the 24v and 12v rails were jumping around like crazy, so it's a PSU issue I reckon.
Its 12v standby rail keeps dying on me, despite the 24v rail being fine. Have a look at the schematic on page 37. On the right side of the page we have the secondary which interests us. D830 is the standby diode. With no load, I get 15v on that rail, which is a bit high to begin with, but if I load the rail, it dies completely, as if triggering overcurrent. If I remove the load, it springs back to life. Already changed the two caps on that rail and it's not it...I'm not sure what to check next. The strange thing is that the 24v rail is fine: if I load that one, no problem: I get steady voltage, but as soon as I apply any load to the 12v one, nothing....I assume TL431 towards the bottom is fine, since there is regulation. There's a feedback issue somewhere, but I can't find it. That mess of components there is where I believe the issue is. Any ideas ? Tests were done with PSU removed with nothing connected to it, so by "load" I refer to a lightbulb. Cheers and thanks.
It has a hard time starting, requiring multiple attempts before finally staying on and sometimes displays a mess of lines and colors. I thought it was the main board, but then noticed the backlight was flickering too and the 24v and 12v rails were jumping around like crazy, so it's a PSU issue I reckon.Its 12v standby rail keeps dying on me, despite the 24v rail being fine. Have a look at the schematic on page 37. On the right side of the page we have the secondary which interests us. D830 is the standby diode. With no load, I get 15v on that rail, which is a bit high to begin with, but if I load the rail, it dies completely, as if triggering overcurrent. If I remove the load, it springs back to life. Already changed the two caps on that rail and it's not it...I'm not sure what to check next. The strange thing is that the 24v rail is fine: if I load that one, no problem: I get steady voltage, but as soon as I apply any load to the 12v one, nothing....I assume TL431 towards the bottom is fine, since there is regulation. There's a feedback issue somewhere, but I can't find it. That mess of components there is where I believe the issue is. Any ideas ? Tests were done with PSU removed with nothing connected to it, so by "load" I refer to a lightbulb. Cheers and thanks.
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