Samsung PN58B860 Plasma suddenly shutdown and will not restart

[Bobby78]

Newbie here looking for help saving my Plasma...

While watching the TV, it shut down and started clicking and making a high-pitched tone every few seconds like it was trying to restart. Power button was unresponsive.

I unplugged the TV for a few minutes and when it was plugged back the clicking and tone started immediately.

Removing the rear panel, both the noises seem to be coming from the left relay on the power supply board. (At least I'm pretty sure those two black 1" squares are relays.)

I do not see any obvious bad capacitors.
I unplugged cables from the power supply one at a time to try and track down the issue... Only when I unplug the main board (w/all the AV inputs) do the noises stop, but the TV still does not turn on.

What do I do next?

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

So I'm guessing the power supply is made up of both tan colored boards and not just the one on the left.

I disconnected everything from those boards and jumpered out PS_ON to GND and VS_ON to STD5V. (I couldn't get anything on the other 5.3V pins) With this setup the TV goes through one click and tone cycle and then stops as opposed to repeating like when the main board was still attached.

I also tried leaving the logic board connected and jumping test pins 3 & 4. Same result as above.

Now I'm thinking it's the power supply as I can't get any readings on Vs, Va, or 5.3V.

What else can I check on the power supply boards to find the bad component??

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Here are some better pics of the PSU.

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Can you try the jumper test, but unplug the Y-main and X-main boards? These are the large left and right hand boards, when looking from the rear of the TV. Then check the Vs and Va.

Is there a BN44 number printed on the power board? (example: BN44-12345A)

[Ltank]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

You jumpered out PS_ON to GND and VS_ON to STD5V? I would jumper PS_On and VS_On to the 5vdc without any of the outputs connected to the PS. Check to see if the PS voltages turn on. If they do, turn off and unplug set then connect The Y or Z boards one at a time to try to determine which boards are loading the PS down. This is a good starting point

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Tom - I had everything disconnected when I did that jumper test...
Just tried it again to reconfirm, only unplugging the X&Y mains, same result, 0 Vs.

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

OK, on the top of this board
https://www.badcaps.net/forum/attach...1&d=1409683598

There are some 450V blue capacitors. Very carefully, can you try measuring the voltage across any one of them? (Only need to test one of them.)

Careful - high voltage. Risk of electric shock. Do not touch any exposed metal or leads of the meter while testing.

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Ltank - I'm 99% certain PS_ON needs to be low and VS_ON needs to be high on this set. My test was done with all boards disconnected from the PS, so I think I've already ruled out the X, Y and Main. I'm pretty sure it's the PS, since I can't get Vs, Va, or even 5.3V readings. Just trying to figure out where/how to look for a bad component on the PS. Nothing looks melted, bulged, cracked, lose, or even discolored that I can find. Removed both boards and looked front and back.

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Yes, on these PS ON must go low (<1VDC), VS ON must go high (>3VDC)

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Tom - I'm pretty sure I checked all those, but I will do it again since I really don't want to miss anything! Be right back...

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Yup, those caps reach ~140V while the relay is powered.

EDIT: When the relay shuts off, they immediately drop to ~50V.

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Hmm, they should reach 390V. The fault would appear to be on the left hand power board but let's try to make sure. Is there a legend next to that large connector between the left and right hand power boards?

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Here's the legend

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

OK between PRIMARY_GND and PFC IC VCC, what voltage do you measure?

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

14.5v

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Does this change when the PS ON and VS ON jumpers are disconnected?

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

That was with everything connected normally except X &Y disconnected.

[tom66]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Sorry my mistake. Can you try the jumper AND check the voltage on those 450V capacitors.

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

With PS ON jumped it is still 14.5V

[Bobby78]

Re: Samsung PN58B860 Plasma suddenly shutdown and will not restart

Still 140 with both jumpers