Re: Polaroid FLM-373B Power LED but no picture, already tried replacing caps
Thought maybe you guys who have helped me would like an update on this... The "freezer spray" test didn't help figure anything out, but by hooking up a 9 volt battery to the pin that was causing problems, I was able to narrow the problem down to a tiny little area by checking voltages across the series of capacitors on the board (one had voltage across it, then the traces went through a few tiny little surface mount things, and the one after that read 0v).
I realized that even if...
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Re: Polaroid FLM-373B Power LED but no picture, already tried replacing caps
Well this should be a great time. There's a replacement main board on ebay for $80 that I might just grab, I feel like I'm not gonna be able to figure this one out. I've determined that when I unplug the wire I circled, the TV mostly powers up (backlight comes on, but nothing appears on screen), so something powered by that is causing the problem. I'm thinking this is still gonna be quite difficult though....
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Re: Polaroid FLM-373B Power LED but no picture, already tried replacing caps
Ok, tried a few things. With everything unplugged and a resistor between 5VSB and STB, the power supply outputs all the correct voltages. With the inverter board plugged in and the resistor connected, the voltages are also all correct. When the main board is connected, however, the voltages all drop to zero.
With everything plugged in, connecting the resistor between GND and STB has no effect. I'm kind of afraid of running a direct jumper wire between GND and STB because I don't want to blow...
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Re: Polaroid FLM-373B Power LED but no picture, already tried replacing caps
It looks like that is the correct data sheet for this power supply, that is an impressive find. I still can't determine where PS_ON is though, I don't see it labeled anywhere on the board. I've attached a couple pictures of where the main board plugs in, hopefully that will be helpful. Sorry for the quality of the pictures, I lost my camera charger when I moved so I had to use my phone....
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Re: Polaroid FLM-373B Power LED but no picture, already tried replacing caps
Sorry to not respond for a week, I moved to a new state and started a new job, so I haven't had any spare time.
Now when I check the voltages, I'm getting .704 from pin 1 to the case, and -1.243 from pin 1 to the tab.
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Re: Polaroid FLM-373B Power LED but no picture, already tried replacing caps
Readings from the LDOs, taken left to right if pins are facing downward:
U3: 0, 3.30, 5.15
U4: 0, 1.798, 3.30
U5: 0, 3.29, 5.12
U6: 0, 1.798, 3.28
U7: 0, 3.28, 5.14
U13: 0, (no pin), 4.34
U33: 0, (no pin), 3.53
One thing that seems strange to me is that I was reading these voltages even after the power supply cut out and wasn't supplying any power other than the +5VSB.
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