Black screen! Oh no!
 

I've got a 40 in. Polaroid LCD TV. when I try to power it up I get a black screen. The audio is fine. When it worked right, the word "POLARIOD" would show for a couple of seconds and then it would go to the picture on whatever channel I was on. Now, sometimes the word POLARIOD just barely flashes and then the screen goes black. Does anyone have any idea what may be wrong?:scratch2:

Thanks for your time,

John

I have a Toshiba 32HLC56 that did the same thing. It's called "2 seconds to black." Info can be found here:

http://www.badcaps.net/forum/showthread.php?t=10419

My problem ended up being a bad transformer on the inverter board. I could have replaced the transformer but instead I found a used inverter board on eB*y for the price of one brand new transformer so I just swapped boards. Your problem could be as simple as mine or something more involved. Maybe someone with your make and model can give you more info.

The floursent back lights are not coming on. Usually a problem on the inverter board. It should be the board the tubes connect to. There is a transformer for each tube I think. Dont hold me to it though. Someone on here is likely an LCD repair expert and may be able to help. The Polaroid sets did have some capacitor problems I have heard as well. So power to the inverter is also suspect.

Thanks. I'll start checking those things that I can and hope its something simple as I have no background in this kind of thing.

Capacitors fail rapidly on these sets. If it is one with the removable hatch in the back, it will reveal the module easier than most.
If caps don't repair it, keep in mind some of the Polaroid sets are devils to use, even with the correct remotes!
I have to say, I don't give them as much effort as other LCD sets as I find their picture a bit poorer than most.

I have been using this in my garage so picture quality is not of prime importance. It was working fine and then....:sigh:

Thanks for your time though.

Good morning,

I tried the flashlight trick and there is a picture in there! :banana: Now how do I get it out? I'm assuming there is a problem with florescent lights?

Thanks,

John

John,

The CCFL tubes might be OK though something on the inverter board might have failed. What model Polaroid is it?

POLAROID 40" HD Widescreen TLA-04011C

Thanks.

Here's an inverter board for a TLA-04011C set. Not sure if it's exactly what you have as the model number seems to be used on many sets having different size screens.

http://www.ebay.com/itm/POLAROID-TLA...-/190696895817

I'm not telling you to purchase it but now you know what to look for when you remove the cover from your set. Of course, unplug the thing first.

If you discover what model transformers are on the board (big rectangular things with coils of wire) you can than test them using a voltmeter in resistance mode. Hopefully someone on this forum has experience with your model television that can help you out.

Thanks for the info and link. I've got to get the set off the wall so I can open it up. (Time for a call to my neighbors!:D) I'll keep in touch and let you know what I see.

Thanks,

John

I finally got the set off the wall and opened it up. It is entirely possible that this connector (see picture, at top, white plug) was off when I took the back off. I did not have to unplug it like I had to do to all the others. If that was unplugged, that would explain why I had no back lights wouldn't it?

Thanks for your time,

John

Update. I plugged the white connector back in and powered up the TV. The back lights came on for a second and went back out. When they were going out, I heard a bacon frying sound:sigh: that came from (I think) one of the black rectangular things at the top right of this picture. At the same time a little red light located to the left in the picture came on. Does this mean I have to replace this whole board, or just the rectangular what-chama-call it? BTW, I know next to nothing about soldering.

Thanks,

John

Those are the HV transformers for the inverter. One is probably going tits up.

Does that mean replacing the board?

Those Polaroid branded HDTVs are not the best sets in the world, or so I gather from what I've read about them online. If yours is going to need more than a new inverter board, I'd just replace the entire set. I'm not sure if individual modules are repairable at the component level or not, but I'd guess not, considering they have surface-mount components and are wave-soldered by machine at the factory. That these TVs are not made by a known manufacturer (most aren't, unfortunately) is not a factor in your favor either. :no: I don't know how big your set is, but if it's much less than 32 inches or so I'd junk it. Smaller screen HDTVs are just not worth repairing, as the cost of repairs (added to that of the initial diagnosis) can and all too often does exceed the price of a new set.

Take a close look at the little blue ceramic capacitors next to the transformers. I have seen those go. They usually darken when they fail. (Sometimes they darken to the point of being crumbly black soot!) I wouldn't be surprised if one has shorted. Should be around 22pf/6kv IIRC. I usually get them from Mouser.

My set is 40". I found the board I think I need online for approx. $70.00. It would cost about 10 times that to replace the set.

Thanks for taking the time to reply though.:thmbsp:

They look fine from the outside (but what do I know?) I found the whole board online so I think I may go that way. From what I could tell, the frying sound seems to be coming from one of the transformers. Does that sound reasonable to you?:scratch2:
Is it possible for me to test either the caps or the transformers while they are still attached to the board? The board is out of the set now.

Sorry, didn't mean to upset you about the Polaroid. I have a 20 inch early one myself I use around the shop. It does give a good picture on VGA input. It has analog only tuner. I guess I get too many customers who have trouble using their Polaroids and it has kinda turned me against them. As I said, I ususlly run into capacitors bad. I have had a few with the harness going to the screen oxidzing and needing a cleaning too.

Hey, you didn't upset me!:thmbsp: I appreciate any and all comments. All I know about electronics could be put on a postcard, so anything someone wishes to contribute is more than welcome.

As far as my trouble goes, I have ordered a complete power supply board. It should be here later this week. I'll put it in and report back.

Again, thanks to everyone for their replies,

John

Got the new power supply board in this afternoon and.... I'm back in business!:banana:

Thanks to everybody that responded. :yes:



(Took offer down. Probably not the right place for it.)