Samsung HP T5064 clicks on and off, no picture

[bwaindwain]

Yesterday, my neighbor gave me a broken Samsung HP T5064 50" plasma. I've never seen it working properly. When I plug it in:
- the blue light on the front flashes five times
- there's a click from the power board (starting up?) and a very faint hum
- the display (backlight?) comes on very dimly, dark grey with two horizontal black lines,
- three green LEDs come on the small board under the mainboard (two steady, one flashing),
- waits for about 20 seconds,
- clicks again (off?),
- repeat

Power supply board #BN44-00160A

I tested some voltages:
- STD5V is steady at 5.09V to both boards
- VS_ON is 3.21V
- 12V pins are reading 12.02V, drops when it clicks off then comes back when it clicks on
- 5.3V pins are reading as 5.22V, drops when it clicks off then comes back when it clicks on
- VA is 63.3, drops when it clicks off then comes back when it clicks on
- VS is 207, drops when it clicks off then comes back when it clicks on
- fuses are good (0)

I don't see any bulged capacitors. I flipped the power board over and didn't see any loose solder joints. I didn't use a magnifying glass though.

I have a multimeter and soldering iron and am interested to try and resurrect this thing. I'm very new to TV repair, and I really appreciate the good advice I've read on this forum

[bwaindwain]

Re: Samsung HP T5064 clicks on and off, no picture

I have checked with a magnifying glass and can't see any cracked/loose solder joints on the power board.

I've unplugged all connectors from the power board except the one to the mainboard CN801, and it still does the clicking.

On the mainboard, I've unplugged all connectors, plugged in AC, and it does the clicking thing.

[bwaindwain]

Re: Samsung HP T5064 clicks on and off, no picture

I disconnected the main board, shorted ps_on, and got the test pattern to display, thanks to this helpful comment

The display patterns show with all the colors and stuff. I see two thin black horizontal lines on the screen.

I also found a bulged capacitor on the Y bus. See pic.

My completely amateur conclusion is that I have a faulty mainboard.

What would cause the lines? the bad capacitor?

[bwaindwain]

Re: Samsung HP T5064 clicks on and off, no picture

If I reconnect the mainboard, with the jumper on pin 5&6 on the logic board, then the test pattern displays, but it power cycles again every 20 seconds.

[ReeceyBurger123]

Re: Samsung HP T5064 clicks on and off, no picture

I agree the motherboard is faulty, heres a link to my videos on a few mods to help these last longer:

https://m.youtube.com/watch?v=JjQ--2SZdyY

https://m.youtube.com/watch?v=57aDWsiLIxE

[vinceroger69]

Re: Samsung HP T5064 clicks on and off, no picture

would a faulty mainboard cause the two black lines reece? or is that something else

[bwaindwain]

Re: Samsung HP T5064 clicks on and off, no picture

Pushing buttons on the remote makes the blue light on the front flash, but doesn't do anything. So, I guess the IR unit is OK.

I've never heard any sound coming from the tv. Another point against the mainboard.

[ReeceyBurger123]

Re: Samsung HP T5064 clicks on and off, no picture

Yes the Mb is likely at fault, also Vince good point however they seem to be at the same distance from each other so possibly just something in the pattern ? Thats a good question tbh lol

[ReeceyBurger123]

Re: Samsung HP T5064 clicks on and off, no picture

I would also advise you follow my video carefully, recap the Y, Xmain, Psu and then follow other things like heatsinking the buffers, resoldering Psu joints and tightening all screws on the power devices on the Sus boards. After replacing the mainboard that is just to make sure the set is working.

[bwaindwain]

Re: Samsung HP T5064 clicks on and off, no picture

I've re-seated all the ribbon cables on the y buffer board, but the lines are still there. I don't want to spend $ on a new mainboard if it's not going to fix the lines. Do you think I need a new Y buffer board (s) and/or Y main?

[ReeceyBurger123]

Re: Samsung HP T5064 clicks on and off, no picture

Ysus will not cause this, doibt its the buffer either but the panel.

[bwaindwain]

Re: Samsung HP T5064 clicks on and off, no picture

Thanks to everyone for your advice. I think I'll probably send this on to e-recycling.