Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

[Truncatedhose]

I have a Polaroid here with exact same issue described in this thread: (Comes on with Polaroid logo on screen and then shuts down with a static noise heard from speakers momentarily)

https://www.badcaps.net/forum/showthread.php?t=13335

In that thread, replacing the PS/Inv silved the problem, but...

The problem here is, replacing the PS/Inv board did not help; I have the same exact symptom. I don't think I got a bad board. I've check all the blue caps on the edge of the board near the outputs to the CCFLs. I can't figure this one out.

Help would be greatly appreciated!

Thanks!

Here are some pictures. (The 1st PS/Inv picture is of the new one installed and the last one is of the original PS/Inv)

[CapLeaker]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

maybe the CCFL is bad?

[Truncatedhose]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

maybe the CCFL is bad?

That's what I wonder, but there doesn't seem to be a dim area when the screen is on momentarily. Might be hard to tell, though. I have a CCFL tester which I tried, but all I can do is use it to run bank A or B since you can't access the individual wires going to each CCFL, but only the two plugs coming from the PS/Inv board. I'm not even sure the tester can be used to power a whole bank in that way? It seemed check good (in the green), but I didn't turn off the lights to see if it was actually lighting half the lamps...maybe I could check that?

[CapLeaker]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

Check the transformers of the inverter board with your Ohm meter. Should be like within a few percent of each other. Could be also bad cabling of the CCFL lamps, or bad caps. Problem is to correctly test the transformers you'd need a Transformer Ring tester and almost no one has access to such a rig.

[nomoresonys]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

I'd be tempted to recap the mainboard, maybe the 7 bigger ones, maybe all, could be a mainboard issue, maybe corrupt firmware, may be an eeprom issue.

[Truncatedhose]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

Check the transformers of the inverter board with your Ohm meter. Should be like within a few percent of each other. Could be also bad cabling of the CCFL lamps, or bad caps. Problem is to correctly test the transformers you'd need a Transformer Ring tester and almost no one has access to such a rig.

Hi there. I do have a ring tester, but this unit just has a single transformer, does it not? Or is it two built together?

[Truncatedhose]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

I'd be tempted to recap the mainboard, maybe the 7 bigger ones, maybe all, could be a mainboard issue, maybe corrupt firmware, may be an eeprom issue.

I could check those caps, but the main board is developing the BKON (back light on?) voltage to the power supply and it doesn't drop or anything when the TV goes blank. I would think this would be a good sign? If I recall it was around 2.5 or 3.5 volts.

[CapLeaker]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

O.k. shortcut. Unplug all the main board cables from the power supply. Take two 1k ohms resistors and put one between 5v STBY and PSon. Take the other resistor and jumper 5v to BLon (backlight). Plug the power supply in and all voltage rails should be up and the backlight should be on.

[R_J]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

I have had cracked ccfl's that would still come on and work, sometimes they would arc a bit before coming on but would come on, and sometimes they would only flicker and shut off. When I took the panel apart I could see that they were indeed broken. but as long as the glass was touching it would light.

[Truncatedhose]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

O.k. shortcut. Unplug all the main board cables from the power supply. Take two 1k ohms resistors and put one between 5v STBY and PSon. Take the other resistor and jumper 5v to BLon (backlight). Plug the power supply in and all voltage rails should be up and the backlight should be on.

Thank you, I will try that tomorrow and let you know.

[Truncatedhose]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

I have had cracked ccfl's that would still come on and work, sometimes they would arc a bit before coming on but would come on, and sometimes they would only flicker and shut off. When I took the panel apart I could see that they were indeed broken. but as long as the glass was touching it would light.

Yeah, I'm worried that this could have poor connections/sockets for the CCFLs. I will hope to find something else before having to delve that deep.

[Truncatedhose]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

O.k. shortcut. Unplug all the main board cables from the power supply. Take two 1k ohms resistors and put one between 5v STBY and PSon. Take the other resistor and jumper 5v to BLon (backlight). Plug the power supply in and all voltage rails should be up and the backlight should be on.

Okay, so I unplugged both the plugs coming from the Main Board; (the smaller plug I unplugged at the Main Board so I could use the plug holes to push in the resistors at the Power Supply side) and I tried it, but the TV will not power on/nothing happens. I sent a picture to show which pins I am shorting. One thing I noted is that that cable is not using all of it's wires even though the pins are there and labeled on the board. I do get the voltages there (before unplugging anything), but I don't know if it matters that there are no wires going to the Main Board there anyway? Also, am I using the correct pins? See the attached picture.

[Truncatedhose]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

Someone? Thanks!

[CapLeaker]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

what is the pin out on the other connector?

[Truncatedhose]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

what is the pin out on the other connector?

That larger connector to the right? It doesn't have anything printed on or near it on the top side of the board, but here is a picture of it's markings on the bottom of the board:

[CapLeaker]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

jumper there the 5V to the STBY with the resistor, see if that turns it on.

[Truncatedhose]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

jumper there the 5V to the STBY with the resistor, see if that turns it on.

Okay, should I leave the other resistor on the other plug where it is between the BKON and the 5V?

[CapLeaker]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

Well... the BLon is just for turning on the back light voltage. Concentrate on forcing on the PSU first. Once you got it on, jumper the backlight voltage on too.

[Truncatedhose]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

Well... the BLon is just for turning on the back light voltage. Concentrate on forcing on the PSU first. Once you got it on, jumper the backlight voltage on too.

Well, I did that and still nothing. Just sits there dead. I think I might try replacing the Main Board. What do you think? I don't think the PSU is bad having already replaced it and gotten the same exact symptom. The noise from the speakers (like a fairly loud rush/crackle) when the TV shuts down makes me very suspicious of a failure on the Main Board (maybe in the audio circuit) and that's why it's shutting down? Also, I looked very carefully with the lights off from the back of the TV and it seems that all the CCFLS light up before it shuts down and that makes me more confident that it might not be anything to do with them either.

[ReeceyBurger123]

Re: Polaroid TLX-04244B Power Supply/Inv board didn't fix?!

Could you take a good clear photo of the mainboard please, I have had a similar issue on a vestel set where the audio amp was bad, the tv started backlight came one then a crackle and it shutdown, I replaced the amp and it came back to life.