Problem with Samsung ps43d490 PDP

[tom66]

Re: Problem with Samsung ps43d490 PDP

Polarity for Vscan isn't important (well if it went positive it would not work at all!), just look at the actual number "185V". If you get pink tinge from low Vs, increase -Vsc to around -195V.

[mcfly666]

Re: Problem with Samsung ps43d490 PDP

Ah I see, cheers Tom. Unfortunately I had to raise Vs back up to 212v to get rid of any funny business with the panel. It was only until I had some 100% white test screens up I realised how bad it was at lower voltages.

All testing is on hold now till I get the 1.6 xmain as the 1.8 had a funny buzz coming from it - I don't know if its a quirk of the design or if anything was out of spec.

Toying with the idea of tapping into the 5v feed from the usb port in order to run a PC fan or two on the back of the chassis, might help things get a bit cooler.

I'm a bit confused though, I was going to test the Vscan but on the panel it is labeled at being -185v Do I test it in the same way or do I have to reverse the polarity on the DMM?

[tom66]

Re: Problem with Samsung ps43d490 PDP

A bit of a pink tinge is a sign Vs needs increasing, but I'd only increase it to the point that Vs no longer has any effect on the picture.

[mcfly666]

Re: Problem with Samsung ps43d490 PDP

Yeah it's strange, but the pink dots in the corner appeared when the Vs was turned down to 207 and went away when I turned it up to 210. Really strange, but the guy at Emos said that it usually happens with these pdp's and Samsung purposefully overdrive's the panels because of it.

213v which is what the set was originally at was still just in the 2% range so I am hoping that knocking even 3v off the panel will give it back some longevity.

The only other explanation I was given to why the Xmain had failed is that some of these sets suffer from a short in the panel if that's the case the TV is toast, but in my limited understanding a shorted panel will toast the boards as soon as its turned on?

Thanks for keeping with me Tom!

[tom66]

Re: Problem with Samsung ps43d490 PDP

Dithering not affected by Vs. The Vs should be set to the panel spec or excessive heat may be produced in the X- and Y-main boards leading to early failure.

[mcfly666]

Re: Problem with Samsung ps43d490 PDP

Update, just turned down the VS to what it said on the panel (207v) TV does show some pink 'dithering' when showing a white screen now.

It's in the top left of the screen and it shows up as tiny pink dots, I've turned up the VS to 209/210 and the picture seems stable.

Should I test the VS off of the Ysus, Cant see a test point for VS on the Xmain.

[mcfly666]

Re: Problem with Samsung ps43d490 PDP

Hi Tom, VS on the panel is 207v just didn't know if its too far out. I've heard that Samsung sometimes like to drive their panels hard to reduce dithering.

[tom66]

Re: Problem with Samsung ps43d490 PDP

Is the Vs the same as specified on the panel sticker?

[mcfly666]

Re: Problem with Samsung ps43d490 PDP

Again, I've just literally had another go at this set. Spoke to Emos and they are sending out a board as they say I could have been unlucky and had an X-main that was driven particularly hard in its life.

^^ You really can't fault this company, they will bend over backwards to help you!

Anyway I have tested the Va and Vs from the powerboard Va is 59 and Vs 212 The Vs seems a little high?

[tom66]

Re: Problem with Samsung ps43d490 PDP

I assume you mean 207V for Vs and approx 55~60V for Va.

Yes that's correct, your meter if autoranging should be set to volts DC if it has multiple scales set it to the highest V DC scale.

A tolerance of approx ±2V on every voltage is usually used.

[mcfly666]

Re: Problem with Samsung ps43d490 PDP

OK a quick update, sorry for the late reply I'm snowed under with work...

I just literally put the 1.8 X-main in the TV and its fired right back up and seemed to be working perfectly, Which I was surprised with as the noises the TV made when the replacement X-main went were a lot louder than when it went the first time.

I guess it makes sense to test the voltages just in case, I hope you can hold my hand whilst doing it Tom66.

So on the power board there is a POT named 'VA' and next to the POT is an arrow, if I follow that arrow back there is a little silver 'disk' on the board...

I guess that is where the test point for VA is, on the back of the panel is some information regarding voltages. That amongst other things says 207v for the VA.

I guess I take the red end of my multi meter and place that on the test point and then place the black end on the metal chassis when the TV is powered up?

[tom66]

Re: Problem with Samsung ps43d490 PDP

A y-main can damage the x-main but typically you will get no picture.
High Vs voltage can too, but that would not have changed if you did not change it.

[mcfly666]

Re: Problem with Samsung ps43d490 PDP

Have you heard of any other components that can take out an X-main. Maybe an out of spec powerboard or even the Y-main?

[tom66]

Re: Problem with Samsung ps43d490 PDP

I guess put in the 1.8 X-main for a test, I believe Emos has a warranty of at least 30 days on their boards.

[mcfly666]

Re: Problem with Samsung ps43d490 PDP

Yeah the new firmware was installed as well, it was T-MST4DEUC-1029.0 released on the 9 March 2013.

What a bummer

[tom66]

Re: Problem with Samsung ps43d490 PDP

Did you install the 1013 firmware or 1006 firmware?
Could be that the X-main was just worn out but AFAIK the X-main boards usually last a while - at least 3 to 5 years (though not long on the grand scale of things!)

[mcfly666]

Re: Problem with Samsung ps43d490 PDP

Yes that was with the correct version X-main I'm really stumped as to what is causing the problem. I wonder is something else is at fault causing the X-main to go?

[tom66]

Re: Problem with Samsung ps43d490 PDP

Was that with the correct revision X-main?

[mcfly666]

Re: Problem with Samsung ps43d490 PDP

Bad news I'm afraid. I was watching TV when a loud pop came from the TV...

The TV turned off again and is displaying the same symptoms as before with the light flashing twice five times. I think the X-main has gone again.

Is there anything else that can cause repeated failures of the X-main as the firmware is on the latest version, or could I just be unlucky with a worn out x-main?

[tom66]

Re: Problem with Samsung ps43d490 PDP

Great service there. Glad it's working.