DP50747-00 - Symptom Powers on for 3 seconds then protection fault

[crepiduse]

Ok. I have a DP50747 (Sanyo) chassis number 00. I got it for free from a friend when it stopped working. So, it's worth a little to me to fix it if I can under $250 or so.

The power supply relay clicks off and the circuit goes into power fault protection mode with an error LED of 3. 3 is A12 UVP (undervolt protection).

I picked up a working LJ44-00132A power supply (same as one in it) and places it in the tv figuring it would be the problem, however the problem still exists. However with the new power supply, if I take off the jumper next to the error led, it will stay on and static comes out of the speakers. no picture though. the error led without the jumper continuously flashes. if I place the jumper back on and turn the tv back on the light will flash 12 times. If I then unplug and wait 1 minute then try again, I am back to 3 flashes A12 UVP error.

I think the logic board will be the culprit here.... any ideas? I have the FSM available.

[crepiduse]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

I replaced the logic and checked all fuses. I now get power for 3secs then 12 blinks on the Main Supply Error LED1.

There is no ref to what 12 blinks is....... So I am at a loss....

[crepiduse]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

Does anyone have a FSM on this model? I bought the $5 one and it is incorrect for the DP50747-00......

[crepiduse]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

Checked all listed voltages and no problems there. All fets test good, all fuses good, and all trails good that I have the ability to test with my equipment. I am beginning to believe an adjustment is out of whack and have had no luck finding the DP50747-00 FSM. Figured I would ask again.

[crepiduse]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

Decided to work on this one again, replaced power board, and logic board, get 3 flashes A12 UVP.

[cadiman]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

Are you working with a Samsung plasma panel?

You most likely have a y drive or buffer problem or both and you have already replaced too many parts.

I have worked on some older samsungs and I was able to unplug the y drive and see if the power supply would stay on.

Find out what panel you have then research the panel, search old posts, etc.

Logic boards rarely fail.

[crepiduse]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

I agree that I have replaced too many parts, but I have spent little

The issue seemed power related as it is 12volt Under Volt Protection.

If I unplug the y drive it still does the same issue. I have to unplug both y and x.

It is a samsung panel and there are limited threads here and on the web and much less about the issue I am having. Unfortunately it doesn't seem to be a well worked on model.

[rayrod81]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

12V failure on a plasma probably means you have a bad main board. These Sanyos have a history of main board failures.

[PlainBill]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

12V failure on a plasma probably means you have a bad main board. These Sanyos have a history of main board failures.

That is interesting. Philips has problems with the DC-DC converter on their Small Signal Board. The symptom is an overloaded 12V supply. The repair is actually quite easy.

crepiduse, a picture of the main board (top and bottom) would be helpful.

PlainBill

[crepiduse]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

PlainBill, thank you for responding. Which main board? They're the crazy company that labels them all as main. Main Logic, Main Power, Y Main, X Main.....yadda. I will gladly post pics of any you think will help.

[PlainBill]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

PlainBill, thank you for responding. Which main board? They're the crazy company that labels them all as main. Main Logic, Main Power, Y Main, X Main.....yadda. I will gladly post pics of any you think will help.

The board with the signal input jacks; known variously as the miscellaneous main board, small signal board, etc.

I always encourage post an over-all picture of the back TV set with the cover off. That makes it easier to indicate what we are interested in.

Note: Attach pictures with 'Manage Attachments'; don't post inline.

PlainBill

[crepiduse]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

Pics

[PlainBill]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

Good pictures, but I don't see an obvious problem.

One idea (worth every penny you have paid for it), you are looking at an undervoltage error on the 12 Volt line. Where do the 12 volt outputs from the power supply go? If it goes to an audio amplifier, try disconnecting that. If it goes only to the main board see if you can identify where it goes. I would suspect it is used as input power to various voltage regulators.

Bill

[crepiduse]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

That is a great idea, and the odd part is all the traces I have found, have the correct voltages

[PlainBill]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

That is a great idea, and the odd part is all the traces I have found, have the correct voltages

Which would indicate it MIGHT be a detection error.

PlainBill

[crepiduse]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

Ok, and a good way to test that theory?

[PlainBill]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

Ok, and a good way to test that theory?

Locate the circuit that is generating the problem and verify the 12 Volt line is correct.

PlainBill

[CoppellTVRepair]

Re: DP50747-00 - Symptom Powers on for 3 seconds then protection fault

If I were you I'd send the power board for test and service here.

Yes I know you've already replaced it, but I still stay on the opinion that this is what needs to be addressed.

To get you a step further I'd try and activate the power board alone to see if it produces all voltages it is supposed to produce; without load from other boards, that is.

if it still fails with an error code...you know I am right.

if it doesn't...well, it gets more complicated , but it also tells you where to look for the trouble - at the 12V load line.

Still doesn't mean the problem is outside of the board...it can only fail under load, for example.

We do offer a repair service for this power, I am pretty certain about that...just find it at www.coppelltvrepair.com ...

Hope this helps.

Again, based on experience, I'd go for a test/service of the power board first.