FLX-3202 Element made by poloroid

[el3ctroded]

boards segmented into PSU, inverter, and video board.

Backlight flickers and goes off.

Power supply has a number of Rubycons installed from the mfg! No swollen caps, all test good. It has 2 25V rails, the one powering the inverter board goes out after the screen turns off.

Tested all the diodes, all test ok.

I'm thinking bad CCFL...???

[retiredcaps]

Re: FLX-3202 Element made by poloroid

Check the inverter transformer secondaries as identified by

http://lcdparts.net/TransformerDetai...ProductID=2731

[PlainBill]

Re: FLX-3202 Element made by poloroid

That looks like a Darfon inverter. Definitely check the transformers.

PlainBill

[el3ctroded]

Re: FLX-3202 Element made by poloroid

Secondaries range from 2.20k to 2.260k... The 2 secondaries on each trans is wired in series, so I just measured the total on each trans instead of each individual secondary.

Nothing odd with the primaries either.

[PlainBill]

Re: FLX-3202 Element made by poloroid

Secondaries range from 2.20k to 2.260k... The 2 secondaries on each trans is wired in series, so I just measured the total on each trans instead of each individual secondary.

Nothing odd with the primaries either.

Check the individual sections of the secondaries. I made the same mistake and missed a secondary that was significantly lower than the rest. It turned out to be shorted.

PlainBill

[cadillacman]

Re: FLX-3202 Element made by poloroid

hmm i have a little polariod that has been sitting for awhile now( actually forgot all about it) that loses backlight after about 20 secs of bieng powered on.. i wonder if i have a bad transformer too.. hmm... look for a post soon!

[retiredcaps]

Re: FLX-3202 Element made by poloroid

Check the individual sections of the secondaries.

Agreed. It is a simple and quick test.

[el3ctroded]

Re: FLX-3202 Element made by poloroid

All secondaries are 1.08k to 1.10k. Can't check primaries individually without desoldering, they are run in parallel.

Found 4 fuses on inverter board, none of them are bad.

Checked the transistors driving the transformers, none are shorted.

This morning when I turned it on, the backlight flickered rapidly for about 10 sec before I unplugged it. Usually it would only flash three or four times and go out.

[el3ctroded]

Re: FLX-3202 Element made by poloroid

I tried hooking up each backlight individually. All turn on, but two of them, the top two, cause a tick tick ticking noise that occurs when the backlight flickers on. I've heard this noise before on another poloriod screen where I had to replace the PSU (noise from inverter circuit on psu). It sort of sounds like a high-voltage zap, like static. Is that likely from an arcing transformer?

[el3ctroded]

Re: FLX-3202 Element made by poloroid

Well, I removed one of those transformers, and no visible burns on the wiring...

[el3ctroded]

Re: FLX-3202 Element made by poloroid

Using just 1 backlight, the same one on three different coils, generates different sounds. Using it on one the 3rd coil from the top causes faint ticking static noises, the 2nd coil from the top and the top coils have loud ticking static noises.

So is it safe to assume the transformers are bad?

[Th3_uN1Qu3]

Re: FLX-3202 Element made by poloroid

Sounds more like a bad CCFL. Is there any combination of lamp and transformers that *doesn't* make any noise?

[PlainBill]

Re: FLX-3202 Element made by poloroid

Sounds more like a bad CCFL. Is there any combination of lamp and transformers that *doesn't* make any noise?

I agree, this sounds like bad wiring to the CCFL or possibly a bad CCFL.

PlainBill

[el3ctroded]

Re: FLX-3202 Element made by poloroid

Listened more carefully this time. the quieter noise is actually coming from the power supply, and I hear some high-pitch whine in it too when I move close to the power supply.

The louder noise only comes from the top two transformers. Any CCFL that I can get to reach, when hooked to those two transformers, makes that noise... Hook CCFLs to different transformers, no noise. I'll see if I can record the noises.

[el3ctroded]

Re: FLX-3202 Element made by poloroid

In the attached zip file is the sounds.

[el3ctroded]

Re: FLX-3202 Element made by poloroid

I took the screen apart and looked at the CCFLs. No burn marks anywhere I saw.

As for bad wiring; are you talking about a short through the wiring to the CCFL?

I'm leaning toward bad inverter...

[retiredcaps]

Re: FLX-3202 Element made by poloroid

As for bad wiring; are you talking about a short through the wiring to the CCFL?

budm has some pics of bad wiring ...

http://s807.photobucket.com/albums/y...klight%20lamp/

[el3ctroded]

Re: FLX-3202 Element made by poloroid

No discoloration on any of the ccfls or the white rubber ends or any wiring.

[el3ctroded]

Re: FLX-3202 Element made by poloroid

I'm gonna order an inverter board. This guy on ebay has some new ones for cheap. Far cheaper than ordering a few of those transformers.

[el3ctroded]

Re: FLX-3202 Element made by poloroid

All cables attached, but the backlight never turns on except once it flashed. The power supply keeps turning off the power to the inverter board. The power supply has two output rails, one rail for the video logic board, one rail for the inverter. Both measure 22V. I noticed the video board rail drops to 18V when turned on... That seems like a lot...

I've tested all regulators on the video logic boards, they are all ok except one 3.3V one is outputting 3.33, but that's pretty close. I've tested several large caps on the video boards, none bad.

I've tested the new inverter board, all transformers are 1.1k, and all fuses good.