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Old 09-27-2021, 02:57 PM   #1
meeotch
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Default Samsung PN64H5000 clicking when powered, then stuck in standby

My PN64H5000 shut itself off/on/off a few times in succession last night, then refused to turn on again. When I first plug it in, I get five clicks coming from the power board, and the red standby light on the front goes on and off, as does the little green LED on the logic board. After that, the red standby light comes on after a couple of seconds and stays lit, but the TV will not power on. Confirmed by leaving it unplugged overnight.

I opened it up, and didn't see any bulging caps, burnt PCBs, or anything else obvious. Tested the two fuses I saw on the power board (one removable, one in a holder that wouldn't allow removal without bending the ends), and they have continuity. I measured the voltages at the power->main connector, with the cable removed, and everything was in the mV range, rather than the correct values printed next to the connector.

With the main board detached from the power board, no clicking occurs when plugged in.

Note: prior to this, the TV was suffering from a magenta flickering problem: https://www.badcaps.net/forum/showthread.php?t=98223

I did search for the clicking/power issue, and found several threads, with different solutions involving various components. I'm good with some light soldering... but for the time/money tradeoff, I'd probably just replace the boards, rather than spending forever swapping components out one at a time. (Or give up altogether, if the combination of the two problems seems to indicate that the panel is going bad anyway.)

Are there some easy tests I can perform to determine the best course of action?
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Old 09-29-2021, 04:43 PM   #2
meeotch
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Default Re: Samsung PN64H5000 clicking when powered, then stuck in standby

Minor update: with the help of this video forwarded to me by a very kind tech (see vid for source, if you're interested), I jumpered the Vs_on and Ps_on pins, and was able to measure correct voltages at all the power board connectors and test points.

Then another helpful tech at a different shop suggested I check the Z-sustain (X-sustain? It's the board connected to the power board which *isn't* the main board.) for shorts. Sure enough, Vs was shorted to ground.

I pulled the board out, and didn't see any obvious signs of scorching or damage. (There's some white crust along the top edge, and the top connector has some orange sticky stuff on it - see third image above - but that's about it. Maybe a bad transistor?)

The power board seems functional, if my jumpered test was correct. It would be good to know if there are any ways of testing the main / y-sustain / logic board in isolation, or at least without the z/x-sustain board connected, though. So that I don't replace the Z, only to find the whole thing's still broken. And/or to test to see if the short on Z was caused by one of the other board, so I don't blow my replacement when I plug it in.
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Old 10-14-2021, 10:32 AM   #3
meeotch
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Default Re: Samsung PN64H5000 clicking when powered, then stuck in standby

Major thanks to Bobby Kolev (at Coppell TV, which I'm not affiliated with), and an unnamed tech at Quad City Electronics (again, no affiliation - I'm just giving props for the excellent help. The former sent me the video link in my last post, which allowed me to properly test the power board. The latter helped me properly test the Z (X?) sustain board to discover it was shorted.

Bought a new Z board on ebay & popped it in. TV is once again working - result! Who knows for how long, but for someone who got his EE degree 30 years ago and hasn't used it much since, putting those tuition dollars to work was pretty satisfying. And it only cost me $60.

Bonus: so far, no magenta flickering, as described in my other thread, linked in the OP above.
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