Re: Samsung Plasma PS63p76FD power cycling / relay clicking - PSU board?
Dragging this one back up to the top again after leaving it in the garage for a month or two!
I have tried replacing the opto-isolator - no luck, it does exactly the same. There's something very odd going on, as the set behaves normally whenever I am probing the voltage on the dc side of the opto. Somehow the voltmeter probe is causing a transistor or IC to stay switched on. This still happens even if the other leg of the DVM is waving around in the air!
I'm wondering if one of...
djtom
Member
Last Activity: 02-15-2023, 06:23 AM
Joined: 11-07-2015
Location: Uk
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Re: Samsung Plasma PS63p76FD power cycling / relay clicking - PSU board?
Stranger and stranger! IT WORKS! (Sort of)
I was probing around on the PSU checking voltages and trying to trace the PsOn circuit across the board when noticed that there was one place that when I measured the voltage, the relay stopped clicking and stayed on! No idea why - it is not a dry joint or a physical contact issue, so I can only assume that the minuscule capacitance or resistance of the DVM must be making the difference between switching a transistor (or not).
The magic...Leave a comment:
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Re: Samsung Plasma PS63p76FD power cycling / relay clicking - PSU board?
Currently struggling to follow the PsOn lines across the board. It seems to switch two transistors but I'm getting confused trying to follow it after that. Any idea where I can find a schematic for it?
It's from a Samsung PS64P76FDX tv, and the board is a BN96-03736A, also labelled as PSPF771F01A.
According to shopjimmy the board is also used in the FP-T6374, unfortunately I can't find a service manual for that either! I've tried elektrotanya and various Google searches. Any ideas for...Leave a comment:
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Re: Samsung Plasma PS63p76FD power cycling / relay clicking - PSU board?
I'm pretty sure that the fault must be on the LV side of the PSU. I've tested all of the LV supply voltages both with and without VSon jumpered, and the same happens whether the HV side is energised or not.
Stby sits happily at 5v throughout, before PsOn is grounded, whilst it is grounded, and after the relay has clicked off again after 2 sec of operation. No change throughout.
All other voltages (12v, 18v, 5.3v) go from 0v to their respective correct values as soon as PsOn is...Leave a comment:
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Re: Samsung Plasma PS63p76FD power cycling / relay clicking - PSU board?
Thank you Andrew. I loaded Vs as you described with 100w bulbs, disconnected everything except the AC input, shorted PSon to gnd and VsOn to 5.3v with 22ohm resistors as before.
On switch-on, everything acted as it did without the load. Relay clicked on, bulbs came on brightly, then after 2 seconds the relay clicked off and it shut itself down again. The only difference this time is that when you remove and reapply the power, it stays dead unless you leave it unpowered for 15-20 seconds before...Leave a comment:
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Re: Samsung Plasma PS63p76FD power cycling / relay clicking - PSU board?
Ok, time for an update on this thread.
I've disconnected everything from the PSU and powered it up. Nothing happens, which is to be expected. Connected a 22ohm resistor to ps-on and took it to ground, at which point the PSU clicked on, stayed on for 2 seconds then clicked off and stayed off. Va comes up to 65v then turns off again.
Did the same again but this time also shorting vs-on to 5.3v with another resistor. Same thing happens - on for 2 sec then goes off and stays off....Leave a comment:
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Re: Samsung Plasma PS63p76FD power cycling / relay clicking - PSU board?
Getting a bit stumped on this one now. Can't see any dry joints on the board anywhere, nor any obviously fried components. Fairly convinced that it is the PSU board at fault, as it clicks in and out with nothing but the control board attached.
Anyone got any ideas as to where to start looking to narrow things down?Leave a comment:
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Re: Samsung Plasma PS63p76FD power cycling / relay clicking - PSU board?
Yep, all fuses that I can see check out ok. Both main incoming fuses, 3 x 20mm fuses and a ceramic are all that I can see and they all test ok.Leave a comment:
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Samsung Plasma PS63p76FD power cycling / relay clicking - PSU board?
Hi all,
Currently working on a huge 63" Samsung plasma. Symptoms as follows - as soon as power is applied, the relay on the PSU board clicks and the blue power light comes on. 2-3 seconds later, relay clicks again, light goes off. Repeat ad infinitum. Tried disconnecting y-sus, same symptoms. Tried disconnecting y-sus AND x-sus, same symptom.
Can't see any obviously bad caps on the PSU board or any blown FETs. There are a couple of bulging caps on the y-sus board (huge 680uF 350v ones!) but otherwise all looks ok.
Va comes on and sits at 65v during... -
Re: New Members - please post your introductions here
Hi all, looking forward to getting stuck into fixing a huge Samsung that I picked up for a song.Leave a comment:
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