Samsung PN58B860 Plasma suddenly shutdown and will not restart

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

I believe I am testing it correctly...

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

OK, try isolating DM808, DM809, DM810 (near the bottom of the power board), see if the short disappears. You can chop one leg on each mid way, so you can solder it back together later if necessary.

Yep you are testing correctly.

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

All 3 Isolated. Still reading 0.4 ohms.

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Also, those three diodes check out OK reading 0.5 in one direction and open in the other.

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

0.5V and open, right?
Next step, you will have to remove DP803, DP804 and check them for shorts.

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Any tricks for removing that massive heat sink they're trapped by? My 30W iron and 30W desoldering pump won't touch it.

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

The best you might be able to do is cut the leads, unscrew the device, and pull it out. Remove the leads using your iron. Installation will be a right pain... but you might be able to do it with a pair of needle nose plyers.

For testing, you could just cut the jumper leads that connect them to the rest of the board, as long as you can reattach them.

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Pulled the 1/3 jumpers and both diodes read good, 0.4 and open.

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Across where the diodes used to be, do you still see a short?

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Yes for both

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Odd.
Is DP801 (top corner of PSU near 450V caps) OK?

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Nope, it's shorted out! Removed from board to double check as well.

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Bingo... last one I would have expected too! I think from the design you can temporarily run the TV without it. See if it works. Then replace it.
(Without this diode, standby current will go through PFC inductors, which will cause excessive conducted emissions... don't tell the FCC...)

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

TV IS ON!!!!!!!!!!!!!!!!!!!!

Wow, that might be the most rewarding thing I've ever done!

I don't know why you spend so much of your precious time helping people for free, but I'm sure glad you do!

Thanks Tom!

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Awesome! Now, go and replace the diode, don't watch the TV for a few days without the diode.

I help people because it's rewarding to keep good TVs out of the trash. Plasma is a dead technology, but there's nothing commercially available that can replace it, save from OLED... and that's far too expensive and only available in curved 55". Nothing beats the image quality of a good plasma TV.

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Will do. I hope to keep this one running until OLEDS come down in price.

[petephipps22]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

I had this exact problem crop up last week in our Samsung PN58B860. Thanks to the troubleshooting help from this forum, I was able to determine that the main board had failed. I got a replacement in, and our TV again works great! Thanks to you all!