Samsung pn51e450a1f no video

[crdz66]

Hello everyone.

I have a friend samsung plasma tv with no video.
Everytime when turns on, show very bright backlight for a second and the tv keeps on but with no video.
I already check the vs,va and show voltage for a sec and drop.
Something weird is vs show 250 volts when according the panel need to be 203 volts around.
The x and y board doesn't show a shorts.
Even the buffer show good.
The logical control board show blinking light every 3 seconds.

I don't know what is the problem.
Any help can be appreciate.
Thanks

[crdz66]

Re: Samsung pn51e450a1f no video

the red light at front blink 6 times

[ReeceyBurger123]

Re: Samsung pn51e450a1f no video

Your Vs wont be that high your measuring it wrong because the Tv would shut off if so. Have you tried running the test patterns ?

[crdz66]

Re: Samsung pn51e450a1f no video

yes but doesn't work

[ReeceyBurger123]

Re: Samsung pn51e450a1f no video

So the screen stays lit up grey (not backlight called prime glow on Plasmas) but you dont get the test patterns when you jumper the pins on the control board ?

[crdz66]

Re: Samsung pn51e450a1f no video

on control board can't find the pins for run
no backlight
it turn just for a sec (bright white) and keeps off or grey.
the test patterns I try to running from remote control, you know mute-182-power on

[jotto]

Re: Samsung pn51e450a1f no video

I have just started working on one, seems that board is like mine, but not sure about the power supply BN44-00509B and main board BN94-06039B.

If you have the same unit as me, then look at the power supply that feeds the main board, remove the cable from the main board side. If you have a meter with small probes you can read it on the connector area that doesn't have a connector right next to the output from the power supply. If not try and find some small wire (I use old capacitor leads that fit and doesn't expand the pin) that you can slip into pin 1 ps on and pin 5 ground on the right side of the connector as your looking at it. That will be your ps on and ground and be about 3.7 volts dc. Pin 2 vs on is 5 volts. If you have both of those which I expect you do since it does flash on. If you want to start you power supply disconnect the other connector feeding off the middle right, you going to only be checking the power supply with no loads connected. Now short pin 1 to pin 5, now all the other voltages should come on, if you have a load tester you could put them under a small load, but be careful if you don't know the load specs. But more then likely your alright if they all turn on after you short the pins.

That is all I can tell you right now. My problem is different, doesn't come on at all. I haven't turned mine on yet, so if you like you can wait, but I am correct on the start up circuit. I have only checked the ps on and vs on, both are correct.

[jotto]

Re: Samsung pn51e450a1f no video

Power supply tested good, replaced the main board since it was only 13.00 and I didn't feel like troubleshooting the board. Unit works fine now. There seems to be two different units with the same model number. Mine has the PS, Main, Tcom, x and y board. The other seems to have the x&y on the same board.

[nwcs]

Re: Samsung pn51e450a1f no video

I have this model and I have never had a plasma tv that all voltages are good and I get the test pattern ok when i short pad pins 3 and 4 and pin 1 and 3 on power connector to smps but no picture in normal mode. I suspect main board. Is there anything else I should look for?

[ReeceyBurger123]

Re: Samsung pn51e450a1f no video

Reflow mainboard likely bga solder issue.

[nwcs]

Re: Samsung pn51e450a1f no video

I have to make a correction. The one voltage that is not correct is PS On. It goes from 1.7v to 0v. I will try the reflow.

[nwcs]

Re: Samsung pn51e450a1f no video

Also can not turn the tv off with remote or power button. Not sure if I am able to change inputs to verify audio

[nwcs]

Re: Samsung pn51e450a1f no video

This ended up being a bad main board. Replaced it and now all works fine.

[ReeceyBurger123]

Re: Samsung pn51e450a1f no video

Thanks for the update