Samsung PS51D6900 not turning on, dead.

[kikujiro]

Hi guys,
I' m new in the forum and I need your help.

Yesterday I pressed the button on remote control to turn on my TV, but nothing happened, front light red is off, but no video, no sound, nothing.

I unplagged all cables (hdmi, etc.) and i opened the back panell to take a look, fuse ok, nothing obvious.

I try to plug it and... the light red comes on and tv turns on.
Reconnect all cables, but after 2 hours, while watching sat, TV is turned off again. Unplagged again all cables and tv turned on (i suspect HDMI sat reciever cable)

Today same thing, while tv was in standby, I saw the red light go off, and TV will not switch on, dead.

Before calling technical support, I would like to do some tests with your help
Thank you

[tom66]

Re: Samsung PS51D6900 not turning on, dead.

Please take the back cover off your TV and post some good clear pictures of the parts inside the TV.

[kikujiro]

Re: Samsung PS51D6900 not turning on, dead.

Good morning Tom,
here some photos of boards

Thanks
Alessandro

[Ltank]

Re: Samsung PS51D6900 not turning on, dead.

1st step. Look for obvious problems like burnt parts. Check P.S.
Fuses then voltages as marked on the P.S. using metal frame as gnd reference when checking output voltages. Check VS and VA voltages. If not present or low remove the connectors and test voltages again. Be sure you Unplug tv and wait several minutes before unplugging or reconnecting cables.

[tom66]

Re: Samsung PS51D6900 not turning on, dead.

Since TV is stuck in standby, I'd like to first try forcing the PSU on.

Disconnect cable between power board and main board. (Main board has HDMI ports. Power board connects to mains electricity.)

Using the pin legend on the power supply, connect a wire between the PS-ON and any of the RTN pins. Then plug the power in to the TV. Using a meter, check the various other voltages: Vs, Va, 15V, etc.

[Th3_uN1Qu3]

Re: Samsung PS51D6900 not turning on, dead.

Red light go off makes me think a problem with the standby power supply.

[tom66]

Re: Samsung PS51D6900 not turning on, dead.

On Samsung sets the power light being off means it's turned on... if it's working... so it could be a main board fault or a power board fault.

[kikujiro]

Re: Samsung PS51D6900 not turning on, dead.

1st step. Look for obvious problems like burnt parts. Check P.S.
Fuses then voltages as marked on the P.S. using metal frame as gnd reference when checking output voltages. Check VS and VA voltages. If not present or low remove the connectors and test voltages again. Be sure you Unplug tv and wait several minutes before unplugging or reconnecting cables.

Hello, I have not seen burnt parts
I placed red lead on VS-adj then black on ground point and got 0v, same value whith VA-adj
I waited 30 minutes and then I unplugged all cables... same result, 0v both.

[kikujiro]

Re: Samsung PS51D6900 not turning on, dead.

Since TV is stuck in standby, I'd like to first try forcing the PSU on.

Disconnect cable between power board and main board. (Main board has HDMI ports. Power board connects to mains electricity.)

Using the pin legend on the power supply, connect a wire between the PS-ON and any of the RTN pins. Then plug the power in to the TV. Using a meter, check the various other voltages: Vs, Va, 15V, etc.

Hi Tom,
is that correct? connect a wire between pin 1 and pin 3 as in picture?

[tom66]

Re: Samsung PS51D6900 not turning on, dead.

Yes that's correct, although it will be easier if you just leave the wire harness connected on the power board end, and put a wire between the exposed holes on the open connector.

[ibgm]

Re: Samsung PS51D6900 not turning on, dead.

The picture that shows the sticker with the model # on it has a 47uF cap that looks like it was about to let go. Look closer at that pic, it appears that the dimple on the 2nd one in is deforming.

[kikujiro]

Re: Samsung PS51D6900 not turning on, dead.

Yes that's correct, although it will be easier if you just leave the wire harness connected on the power board end, and put a wire between the exposed holes on the open connector.

Great news,
after connecting the wire and plug the the power,
the green light start flashing, but VA and VS were always 0v, at this point I think I make mistakes in the measurement method.
So, I unplagged power, and reconnect main board. Red light in front comes on and TV turned on...
Great, but what happened? maybe a failure in some HDMI ports?

Thanks Tom

[tom66]

Re: Samsung PS51D6900 not turning on, dead.

I am sure it will only be temporary. You should wait until it goes wrong then do some more tests.

[kikujiro]

Re: Samsung PS51D6900 not turning on, dead.

I think so too. I will keep you updated

Alessandro

[kikujiro]

Re: Samsung PS51D6900 not turning on, dead.

Hi,
here I am again, unfortunately the problem has come back.
Last night, while the TV was in standby, the red light is off and the TV is not turned on.
I tried forcing the PSU on, as Tom wrote me, but... nothing, no green light flashing and TV still off.

[ibgm]

Re: Samsung PS51D6900 not turning on, dead.

Did you take a closer look at the Cap in picture DSCF4310? The second cap in is clearly showing signs of bulging out, unless it's the camera angle.

[tom66]

Re: Samsung PS51D6900 not turning on, dead.

Hi,
here I am again, unfortunately the problem has come back.
Last night, while the TV was in standby, the red light is off and the TV is not turned on.
I tried forcing the PSU on, as Tom wrote me, but... nothing, no green light flashing and TV still off.

Ok, this indicates there may be an issue with the power supply. Can you locate the 5V standby pins on the connector and test them, when the set is not working, need to see if standby voltage is still present or not.

[kikujiro]

Re: Samsung PS51D6900 not turning on, dead.

Did you take a closer look at the Cap in picture DSCF4310? The second cap in is clearly showing signs of bulging out, unless it's the camera angle.

Yes, the cap is ok, it's the camera angle
thx

[kikujiro]

Re: Samsung PS51D6900 not turning on, dead.

Tom, I checked the pin 2 (STBY) with the gnd, the voltage is 0v

[tom66]

Re: Samsung PS51D6900 not turning on, dead.

Ok, good, just to make sure, can you unplug all connections except the mains power to the power supply and see if the STBY 5V is still missing.

If so, please take the board out and get clear photos of the top and bottom of the board. I need to be able to see the small circuit traces.