Polaroid 3211-tlxb

[junktv]

Re: Polaroid 3211-tlxb

Not seeing a 50 pin connector.

[CapLeaker]

Re: Polaroid 3211-tlxb

I see corrosion on the bottom right.

[junktv]

Re: Polaroid 3211-tlxb

I noticed that and cleaned it up already. Also noticed a weird jumper on the back.

[CapLeaker]

Re: Polaroid 3211-tlxb

Not seeing a 50 pin connector.

He meant that big 37 pin connector on the back side.

I noticed that and cleaned it up already. Also noticed a weird jumper on the back.

I got no clue what that's for.

[junktv]

Re: Polaroid 3211-tlxb

I'm still not sure why I went and got resistors or exactly where I was supposed to be connecting them. Think if I just replace all caps and the fet/resistors/diods whatever mounted to heat sinks it would work?

Can't find a manual.

[CapLeaker]

Re: Polaroid 3211-tlxb

Nope... I don't... That's just randomly throwing parts around. Got to find what is acting up first. Is it the mainboard not sending the correct signal or is it PSU. We still haven't confirmed yet what the state of STBY, PSon and BL on is when your TV acts up.
Frankly I don't really think it is a PSU problem, I am leaning more towards the main board.

[junktv]

Re: Polaroid 3211-tlxb

Exactly how do I figure that out?

[budm]

Re: Polaroid 3211-tlxb

So far you already know which pin is the PS-ON (STBY) pin thay you can monitor.
If you look at the inverter board, you will see the White and the Yellow wires, one of them is the BL-ON, and another one is the DIM control pin, those two wires are connected to that big female connector on the chassis which is mated to that big connector of the main board.
So you can monitor the DCV on those two wires on the inverter board to see if they disappear when the TV stop working.

[junktv]

Re: Polaroid 3211-tlxb

White is 4.75 to 0 after pop.
Yellow is .03 on to .045 after it shuts down. Jumps to 3.12 on start up.

This is with everything plugged in.

[budm]

Re: Polaroid 3211-tlxb

So when the TV acts up, you lost the PS-ON (STB) per post 9 which will cause the 24V to run the inverter board to disappear, you also lost the signals on the two wires to the inverter board. You have problem in the main board.

[junktv]

Re: Polaroid 3211-tlxb

Probing around while it was off and on to find what had the same voltage the sound shut off but backlight stayed on and power button wouldn't work. It's back to starting up after unpluging it now.

[budm]

Re: Polaroid 3211-tlxb

You already know what signals are missing after it pops, so unless you are trying to locate the failed component on that main board you will need the diagram of the main board to really locate the bad part/s. We know it is the main board problem, and since you lost 3 signals, then it has to be something around the processor circuit.

[junktv]

Re: Polaroid 3211-tlxb

Yes I'd like to fix it. Weird that a tv of similar design to my crappy one just fails while mine has had power supply issues twice. Maybe I can poke around and start labeling what's hot and what's not and voltages. I'll pull the board and look real close for cold joints in some good light. Really wishing I knew more about this stuff but i'm more of a mechanical type. If nothing else I'll toss it in the garage with the Sharp LC-30HV4U and Magnavox 42MF521D/37B that don't work either.

Guess now to decide low end sony or samsung for a replacement.

[CapLeaker]

Re: Polaroid 3211-tlxb

Your problem is on the 5V rail on that main board and x2 what budm said in his last post, problem being either the processor itself or around it. Since there was corrosion on the board earlier, I would not be surprised if there are cold solder joints underneath the processor itself ( the one with the silver heatsink on it) You could try a reflow or bake it for a while as a last ditch effort.

[junktv]

Re: Polaroid 3211-tlxb

Hit every solder joint on the bottom and a few on top with a dab of silver solder and nothing. Then did a bake after covering most of the board top with foil leaving cpu open. warmed to 200° then let sit a couple minutes then 450°F for 2 minutes and opened the door. Not having any liquid flux I didn't figure that would work anyway.
Same as before so I'm sticking a fork in it and calling it done. Maybe someone who knows what they are doing will have success with one of these later and I'll try that fix.
New 48" sony 510c took it's place and all is well.

Thanks for the help guys.