Samsung PN43D440A5D Plasma will not power up.

[tech2014]

The set comes on with the samsung power on music, but the screen is black and no video or picture. My VA/VS voltages both drop right away and the led on the logic flashes slowly, indicating an issue. I get my DC voltages on the power supply, just VA/VS drop after power on.

My VS-ON comes up at 5v at power up then quickly drops back to 0V, and the VA/VS voltages disappear. I know the VS-ON comes from the main board, so is this a possible main board issue. Its not the p/s as I replaced it with one in my shop.

See pics below.

[tech2014]

Re: Samsung PN43D440A5D Plasma will not power up.

It was the Y-Main. shorted diode and surface mounts on back of board.

[shootmenow]

Re: Samsung PN43D440A5D Plasma will not power up.

Hello,

I have the same issue now. The TV will not turn on and making clicking noises. I noticed some raised caps on the middle board.

The board with raised caps:



I have a technical background but no experience with TV repairs. How do I go about figuring out which board is the issue?




Kind Regards,
Shootmenow

[tvtimmy]

Re: Samsung PN43D440A5D Plasma will not power up.

Unplug this connection and try to power on. Get the kid away from the LEATHAL voltages that are in tv. You most likely have 3 or 4 blown transistors underneath the x-main. I use fgd4536 as a substitute.

[shootmenow]

Re: Samsung PN43D440A5D Plasma will not power up.

After unplugging that board, I turned on the TV and heard the Samsung startup tone. So what does that mean?

Do I replace all the transistors underneath the board or is there a way to check which ones are bad?

Thank you so much for your help.

[freakaftr8]

Re: Samsung PN43D440A5D Plasma will not power up.

That means you probably have your VS voltage back. Check and see if voltages are there now. Check all 3 pin black devices that are screwed to aluminum heatsinks with the designator starting with a Q. See if thier shorted. These are mosfets. This will be your problem. Also for good measure replace any swollen caps on power supply. It's always a slight possibility that the power supply has enough power to generate voltage on one board but not both.

On another note... Power supplies hold a lethal voltage, even weeks after being unplugged. You really should not let the child around that opened tv. Any part inside if touched wrong could be fatal!

[shootmenow]

Re: Samsung PN43D440A5D Plasma will not power up.

Thanks. Can you point me to a guide on how to check voltages?

I will be more careful with my kid.

[freakaftr8]

Re: Samsung PN43D440A5D Plasma will not power up.

Set your meter for DCV. Black probe to chassis. Red.probe to VS pin off power supply. Turn on tv and check voltage.

You cab stick pin of probe into the connector so it stays there when you turn on the TV. Check at the connector going to the Y main. This this the board opposite of the one yoiu disconnected.