Samsung LN32A450C1DXZA won't power on

[TheWraith]

Looking at a TV for a friend. Power supply (BN44-00214A) appears to be ok. I can pull the PS_ON pin High and seem to be getting the proper output voltages. My problem appears to be with the main board, BN97-01995D. As soon as I plug the main board into the power supply, the power supply turns on. The main board is supplying ~3.5v to the PS_ON pin. After a few seconds it drops out, power supply turns off, then back on. It continues this cycle until the AC input is removed or the main board is unplugged. I can't find a schematic for the main board ANYWHERE. Anyone have experience troubleshooting one of these mainboards?

[martyparish]

Re: Samsung LN32A450C1DXZA won't power on

Maybe consider the t-con or inverter boards. The main board could be sensing error from one of those boards and shutting it down.

Pictures would probably help get more responses.

[martyparish]

Re: Samsung LN32A450C1DXZA won't power on

Actually just came across this thread

Looks like inverter is a common fault. Check any fuses on it.

[cliff_hootarski]

Re: Samsung LN32A450C1DXZA won't power on

Please supply a good focused picture of the back of the main board.
Look for C102, usually needs replacement.

[CapLeaker]

Re: Samsung LN32A450C1DXZA won't power on

google "budm c102".

[TheWraith]

Re: Samsung LN32A450C1DXZA won't power on

This board doesn't appear to have the c102 cap described in the other threads.
The reason I suspect the main board is due to the fact that it is sending the POWER ON signal as soon as it's plugged in, WITHOUT pressing the power switch.

[TheWraith]

Re: Samsung LN32A450C1DXZA won't power on

Backside

[TheWraith]

Re: Samsung LN32A450C1DXZA won't power on

To the top

[martyparish]

Re: Samsung LN32A450C1DXZA won't power on

POWER ON after plug in is normal for many tvs. You may be correct abt the main board but it sure won't hurt to test any other known faults before digging into the main. Good luck with it.

[CapLeaker]

Re: Samsung LN32A450C1DXZA won't power on

I guess we need to know what the PSon / BLon pins do when the TV goes nuts.

[TheWraith]

Re: Samsung LN32A450C1DXZA won't power on

Pretty sure it's a main board issue. I can heat up the shielded portion of the main board and everything is normal. It doesn't send the PS_on signal until I push the power button. At which point the tv turns on fine. I am going to try and remove the shield and see what I can figure out. Will report back.

[CapLeaker]

Re: Samsung LN32A450C1DXZA won't power on

Look inside that shielded portion and check if you see any capacitors. If you do, change them all with quality caps and report back.

[TheWraith]

Re: Samsung LN32A450C1DXZA won't power on

Here's what's under the shield. Any thoughts or suggestions? There is a tantalum cap on the bottom of the board similar to the c102. Looking at the data sheet it is a 100uF 6.3v looks like it is on the 2.5v line. Was planning on changing that and going from there.

[TheWraith]

Re: Samsung LN32A450C1DXZA won't power on

Got a replacement mainboard for $20, and she's alive again. Thanks for all the input and suggestions.

[budm]

Re: Samsung LN32A450C1DXZA won't power on

Thanks for the follow-up on the repair, $20 is a great deal.