50" Sanyo DP50740 Cycling on and off (Common problem?)

[Glitcher]

Hey I just picked up a DP50740 Sanyo. Once the power button is pressed the tv would flicker for a second and then clicks. Then it would cycle like this every 15 seconds.

I've been reading online that this is a common problem with the main board and there is an available repair kit for it.

http://www.coppelltvrepair.com/p/111...d-pwbmainj4fkf

Upon further research the best I found was that there are 3 SMD components on the main board that need replacing. Does anyone know anything about this problem and which components they are?

[Glitcher]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

Has anyone bought the repair kit?

[Glitcher]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

Well, I've been doing some detective work trying to track down what these components are...

Here's the ebay repair kit, Reading the reviews it seems like it only fix 50% of the reported problem, doesn't seem very reliable.

http://www.ebay.com/itm/SANYO-Main-B...item1e7cf604e7

Kit says it includes: "Kit contains 3 surface mount components."

Found this justanswer discussion on the same tv:
http://www.justanswer.com/tv-repair/...image-the.html

The TV Tech stated: "to remove and reinstall some surface mounted transistors --"

Looking over the main board, I noticed there are a total of three voltage regulators. Are voltage regulators also referred to as transistors? I think its a good bet its these three regulators in the kit. I'll measure their voltages in a bit and report it.

[Glitcher]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

I just replaced the entire main board. The TV turns on fine but now I have another problem...

There is an annoying static sound over the audio whenever louder sounds play. Its very annoying as it almost sounds like a blown speaker. I tried switching out the speakers with others that I salvage but the static is still there. I tried 5 different speakers but no luck...

I looked near the speaker outputs on the mainboard and saw the STA333BW chip for the audio processing im guessing. I took it off and replaced it with the one of my old main board. But no luck either... static is still there.

This is so annoying having fixed one thing and having some other problem.. is this still a problem on the audio circuit???

[Ltank]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

I have one doing the same thing too. I thought I had a bad 1117 LDO IC 6630. because there was not output voltage. I replaced it. Still dont run. Should have followed instructions in manual I found on trouble shooting the TV. The 3.3v is shorted to gnd. Should have checked output pin to gnd and I would have seen it earlier. IC800 (sub-cpu) monitors voltages for problems and kills the PS-on comand. On my set evidently it almost looks like the IC001 the STA333BW audio amp is shorted to gnd. The other LDOs
were not shorted. I get the lowest resistannce on the 3.3vdc line as I get closser to the
audio IC. It and the circuits associated with it use 3.3vdc The audio amp also uses 13vdc. Next week I will get my LeekSeeker out to pinpoint the short. The IC001 had lots of pins shorted but the leads are soo close together it hard to do with fine pointed leads and a magnifier/light. Dont know if I was actually across two pins thinking I had more grounds than the print. Guess I could just unsolder it and see if it goes away but sometimes parts dont come off and go back on very well. Normally if I remove it, I replace it.

[Ltank]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

Audio Amp and LDO

[ricosavy]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

I have same problem on mine i believe it is main board but i am trying to fix it at compentent level. I dont think it is the regulators.also i check on ic800 pin 48 i am getting a voltage reading of 4.5 which tells me that power fail circuit is good and also i have green light and tv responds when i push power button.i also have all my voltages in my power supply.any ideas

[ricosavy]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

Here are my voltages on my regulators
Ic6630
Pin1 .570
Pin2 1.821
Pin3 3.302

Ic6650
Pin 2.097
Pin 3.349
Pin. 5.042

Ic1660
Pin1 7.824
Pin2. 9.072
Pin3. 11.955

They are regulators 1117s adj009 do these voltages look ok.the one i have my doubts on is ic1660

[ricosavy]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

Well maybe I have fallen into the same thing thinking that the main board is the problem but I have gut feeling my problem that lies in the sc board. Last sanyo I fixed the dp50741 I though it was the main board ended being the power supply I had same feeling as I do now that it is the sc board. I just need to find way to test it since service manual just focus on main board and a little power supply not much wiring diagrams sc and ss.I did notice that panasonic tc-p50c2 has same sc board I will check wiring diagram see if it provides some help.any idea on how to check sc would help it is a tnpa5063ab.

[IIMacGyverII]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

Well maybe I have fallen into the same thing thinking that the main board is the problem but I have gut feeling my problem that lies in the sc board. Last sanyo I fixed the dp50741 I though it was the main board ended being the power supply I had same feeling as I do now that it is the sc board. I just need to find way to test it since service manual just focus on main board and a little power supply not much wiring diagrams sc and ss.I did notice that panasonic tc-p50c2 has same sc board I will check wiring diagram see if it provides some help.any idea on how to check sc would help it is a tnpa5063ab.

Have you found the problem with this board? I am having the same problem and I am reading the same voltages as you at those three ICs.

[ricosavy]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

I have not found problem i am thinking it is a software issue with eeprom but i am not sure.If any one has fixed the main board at component level any help is appreciated.I did replace the regulators it did not make a difference.

[ricosavy]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

If i find solution i will post it

[ricosavy]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

I sent mine out to get fixed a placed marks on items i suspected might be bad.he did nothing to regulators but the only thing i did notice he did do something to ic5750 new part number on it is 25q128bvfg.i assumming by what i can tell he replaced it.You can order one on ebay just make sure u order the one for your model number for example mine is dp50740-00.the last two digits are important since the eeprom will be programmed for your model.just make sure it says it is programmed and not a blank chip.hope this helps u.

[ricosavy]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

Pic of chip location

[ricosavy]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

Well after installing part still same problem even thought place i took it too said it was bad.the only part i did not have to test was the sc board which now i am thinking is bad too.so looks like i have two parts that are bad.tnpa5063 ab will see if i can repair the part.

[ricosavy]

Re: 50" Sanyo DP50740 Cycling on and off (Common problem?)

Had a tnpa5063 no suffix off a tc-p50c2 put it in and that fixed my problem the sc board was also bad. Tv is now up and running.