LG 32CS460 No power, blinking red light SOLVED

[coreyand]

So I picked up this LG 32" tv from somebody for $10. The power light blinks three times when I plug it in.

I open it up and look at the caps, they look ok, started testing my voltages, I got 3.3v from the secondary but nothing from the primary. Just to be curious I start testing high voltage components like the diodes on the board. All seemed okay except for this rectifier diode by the mosfet on the primary. It was shorted out. To test this theory I took a much weaker diode and put it in its place. The tv turned on until the diode gave out.

The diode I replaced on this board is labeled D603, its marked MUR460AX here is the data sheet on it http://www.datasheetarchive.com/dlma.../DSA-15712.pdf,
I replaced it with a 31GF6 that had alike values from a old power supply board off a samsung(been stealing parts, why wait for shipping if you dont have to.). Heres the Data Sheet on it http://www.vishay.com/docs/88530/31gf6.pdf Tv now works fine.

I just thought I would share with everybody this was a solution to a problem on this particular LG tv I had. The diode/rectifier is circled in the attached photo.

[budm]

Re: LG 32CS460 No power, blinking red light SOLVED

Good job, that Diode is part of the PFC Voltage booster (Q601, D603, L601), so you probably did not get >360VDC on that main filter cap for the rest of the power supply to run.

[MDI]

Re: LG 32CS460 No power, blinking red light SOLVED

Sorry to bump this old thread.

I attempted the same repair. Replaced the shorted diode with the exact part and the tv will run for about an hour before shorting the diode again.

Any insight to what might be causing the diode to short?

[PotShotScott]

Re: LG 32CS460 No power, blinking red light SOLVED

I'm no expert but I do have an opinion. I started using FLIR One for iPhone to look at my power boards as I fix TVs. Tonight when I stumbled onto this thread I took a photo of my board. Q601 and D603 are white hot when looking at them from a thermal perspective. I desoldered my D603 and it's shorted. I feel as though Q601 might be defective on my board since while I have it together and plugged into power Q601 is hot as well. I could be wrong since I'm not a board level expert. (I was an avionics guy in the Navy but worked on the entire jet - not the individual boards).

Heading over to my local electronics place tomorrow. I can post my results if you like.

[whiz62]

Re: LG 32CS460 No power, blinking red light SOLVED

PotShot, Did you ever figure out your heat problem on the 32 LG? Just replaced D603 on a friends TV but didn't check for heat issue. Been running it for couple of hours and all is well so far. got a diode from local store here and it blew in a couple of minutes. Found an old board off vizio in my spares junk with same diode and installed it and seems fine. Must have been cheap crap from store?

[whiz62]

Re: LG 32CS460 No power, blinking red light SOLVED

PotShot, Did you ever figure out your heat problem on the 32 LG? Just replaced D603 on a friends TV but didn't check for heat issue. Been running it for couple of hours and all is well so far. got a diode from local store here and it blew in a couple of minutes. Found an old board off vizio in my spares junk with same diode and installed it and seems fine. Must have been cheap crap from store?

[JDC]

Re: LG 32CS460 No power, blinking red light SOLVED

You just saved another TV from the landfill, coreyand. Congrats!