Samsung PS43D450A2WXXU power on fault

[jgrimshaw01]

Hi everyone,

This is my first post
I am not TV tech but do know how to use a multimeter.
Here is the situation:

Mother in-law has a plasma, 16 months old, that is now out of warranty.
On initial power up, i.e. plugging into wall socket, the units relays click on/off five times then the standby light flashes v.quickly twice 5 times then pauses then repeats. I have trawled around this forum and done the usual check for domed leaking caps but there is no visual damage.

I have tried disconnecting the x board but it would appear that the x & y boards are piggy backing there power supply i.e. there is only one power cable to the x board, the y board gets it's power from the X board.

After disconnecting the X board (& Y board)the relay on the power board clicked once and a green diode on the board i have labeled plasma06 flashes slowly, on the front of the unit when pressing the power button on the remote the standby light flashes quickly but nothing happens.

The voltages at at Vs & Va are supposed to be 207v & 58v
when read Vs peaks @ 280 and reduces to 0 Va peaks @ 78 & reduces to 0.

Is there a way to check to power supply on its own?

Regards
John Grimshaw

[tom66]

Re: Samsung PS43D450A2WXXU power on fault

On this chassis:
Disconnect Y-Main connector.
Check if set powers up. If it does suspect Y-Main or X-Main.
Disconnecy Y-Main to X-Main connector.
Check if set powers up. If it does suspect X-Main, if not suspect Y-Main.

Y-Main supplies power to X-Main.

X-Main is common failure on this chassis.

[jgrimshaw01]

Re: Samsung PS43D450A2WXXU power on fault

Hi Tom
Thanx for quick response got boards wrong way round

Ok disconnected Y -Main connector relay clicks set no power up pressing power on remote just gives flashing standby led.

disconnected X-Main from Y-Main same as above
checked voltage @ PS-On with everything connected switches between .16v to 3.7v
with the Y or X main disconnected PS-On is .16v

[tom66]

Re: Samsung PS43D450A2WXXU power on fault

It's normal for the set to give no picture with no Y-Main. With X-Main missing you expect a dim picture.

So, you get Vs and Va voltages with Y-Main out?
Check meter battery if Vs and Va are that high. PSU on this model maxes out at Vs of 220V, I believe. 220V is too high, will cause arc-bright image.

[jgrimshaw01]

Re: Samsung PS43D450A2WXXU power on fault

changed battery in DMM.

Vs @ 207v with a gradual fall to zero
Va @ 58v with a gradual fall to zero

[tom66]

Re: Samsung PS43D450A2WXXU power on fault

OK, so they are within panel specification. So, with Y-main in, X-main out, check voltage Vs and Va. Zero for both?

[jgrimshaw01]

Re: Samsung PS43D450A2WXXU power on fault

ok Vs 208v v.slowly down to 1.3v
Va 58v slowly down to zero

[tom66]

Re: Samsung PS43D450A2WXXU power on fault

Check panel in dark room, you should see slight light emission while it works. But I don't understand why Vs/Va would drop slowly...

I am going to be working on this very set this Sunday with a friend, and I believe it has the same problem.

[jgrimshaw01]

Re: Samsung PS43D450A2WXXU power on fault

when power applied a small flash of a couple of white lines appear

[tom66]

Re: Samsung PS43D450A2WXXU power on fault

And then Vs begins to fall?

[jgrimshaw01]

Re: Samsung PS43D450A2WXXU power on fault

yes

[tom66]

Re: Samsung PS43D450A2WXXU power on fault

Does the LED on the control board stop blinking?

[tom66]

Re: Samsung PS43D450A2WXXU power on fault

Here is test procedure for plasma panel and all driver boards, except main (AV) board.

Power off completely - disconnect from wall.
Unplug connector highlighted.
Place jumper across pins 3-4.
Turn on set.
Look for test patterns.

They may look like this (video from another user):
http://www.youtube.com/watch?v=JCtF5...ature=youtu.be

[jgrimshaw01]

Re: Samsung PS43D450A2WXXU power on fault

unit clicks on off 5 times then nothing flashing standby

[tom66]

Re: Samsung PS43D450A2WXXU power on fault

Standby light flashing is normal.

For all Samsung that I know (I have worked on PS42B450, similar chassis) the light should stay lit, then when power button pressed, should flash 4~7 times, then go out. When it is off the TV is powered on.

You may have to jumper across PSON with a 100~470 ohm resistor to force PSU on. I suspect main (AV) board fault.

[jgrimshaw01]

Re: Samsung PS43D450A2WXXU power on fault

is that across jumper pins 3, 4?

[tom66]

Re: Samsung PS43D450A2WXXU power on fault

No.... the connector goes from the main board to PSU. A pin is marked PSON on there. I just realised it needs to go to ground on this chassis.

[jgrimshaw01]

Re: Samsung PS43D450A2WXXU power on fault

Do I keep the ribbon cable disconnected from the mainAV board when I put the resistor in?

Keep me posted with how you get on tomorrow with you pals unit, a big thanx for what you have done so far

Regards John

[tom66]

Re: Samsung PS43D450A2WXXU power on fault

You want to have the 3-4 jumper and that connector disconnected, you are trying to force the power supply on so you can rule out everything except the main board, which is a common failure on these sets.

[jgrimshaw01]

Re: Samsung PS43D450A2WXXU power on fault

Hi Tom
Did what you said with a 100 ohm, relay swithched on and off 5 times but quicker than before do I need a bigger resistor to get it stay on?