Philips 50PFP5532D - X-main issue??

[tn245]

Hi

I'm working on a Philips 50PFP5532D with picture problems (see attached photos). Dim, washed out picture, lots of snow, some pixels slow to update and some image retention. From my reading of this forum I thought bad X-main. This uses mostly Samsung boards.

Ordered and fitted a 'tested' replacement X-main and the problem remains exactly the same.

All voltages are spot on. There's an LED on the control board flashing steadily (LED2002) - not sure if that means something.

What do we reckon? Is the replacement X-main also faulty or maybe control board? How can I test?

Thanks again!

X-main: LJ41-04216A
Control board: LJ41-04220a

[tom66]

Re: Philips 50PFP5532D - X-main issue??

I would say Y-main more than anything. Did problem get slowly worse or just suddenly happen?

[tn245]

Re: Philips 50PFP5532D - X-main issue??

Y-main? Damn, much more expensive and complicated then.

It wasn't my TV so not sure if it was gradual or sudden. Just sent a message to previous owner to ask.

[tom66]

Re: Philips 50PFP5532D - X-main issue??

I would start by checking the Vset, -Vsc voltages.

[tn245]

Re: Philips 50PFP5532D - X-main issue??

I actually haven't found the test points for those. Will check again when I get back to it (tomorrow probably) but they don't seem to be as obvious as the other test points. Unless you know offhand? Y-main is LJ41-04217A.

[tn245]

Re: Philips 50PFP5532D - X-main issue??

Ok I found test points for Vscan and Vsch. I guess they are the equivalent on this board?

Vscan: -189.9
Vsch: -69.9

Have attached the voltages sticker from the panel.

Previous owner says it was fine one night and then the next morning switched it on and this.

[tw2005]

Re: Philips 50PFP5532D - X-main issue??

This is the Samsung panel that has a problem with the Upper buffer failing and going short usually also end up with a blown ysus looking at tha part number.

I wonder if it's worthwhile checking out the buffer iCs and see if some are getting very hot on that top board, maybe the beginning of it shorting out?


That's the only thing I can put forward as a possibility.

[tom66]

Re: Philips 50PFP5532D - X-main issue??

Vsch != Vsc, there is also a Vsc usually.

Vsc: row exclude voltage, negative ramp voltage
Vsch: row select voltage
Vset: initialise voltage

[tn245]

Re: Philips 50PFP5532D - X-main issue??

It's hard to tell. They are all a little warm, some slightly more than others. How hot is too hot?

Also, just in case it is relevant. There are three adjustment potentiometers on the y-main. Long Yset, Yfr and Vset. Adjusting Yfr and Vset produces noticable changes in the image and measurable voltage change. Adjusting Long Yset does nothing at all that I can detect.

[tn245]

Re: Philips 50PFP5532D - X-main issue??

tom66, I've got a Ysc: -104V but can't find Vsc anywhere.

[tn245]

Re: Philips 50PFP5532D - X-main issue??

Coming back to this one after a bit of a break. Where should I go next? Are there any more tests I can do to narrow down the problem?

[tn245]

Re: Philips 50PFP5532D - X-main issue??

In case it helps, I made a video of the problem at: http://www.youtube.com/watch?v=s7SVlnYDsSY

[tom66]

Re: Philips 50PFP5532D - X-main issue??

If that -104V is Vsc it is way too low (not negative enough.) Try adjusting -Vsc control to see what happens?

[tn245]

Re: Philips 50PFP5532D - X-main issue??

Tom, I only have three adjustment points on the Y-main. They are Yset, Yfr and Vscan. Nothing to adjust Vsc that I can see.

Interestingly when I just went to measure that Ysc again it's reading around -85V now.

[tn245]

Re: Philips 50PFP5532D - X-main issue??

Wait a minute. Just reading back through, is Vsc the same as Vscan? I had already posted a measurement for Vscan test point up there as -189.9V, but when you then asked for a Vsc measurement I assumed it was something different. Did you maybe just miss where I posted the Vscan measurement?

[tom66]

Re: Philips 50PFP5532D - X-main issue??

Vscan does equal Vsc are you sure that other voltage was not Vsch?

[tn245]

Re: Philips 50PFP5532D - X-main issue??

No it's not Vsch. I gave Vsch earlier. I realise I've been getting hopelessly confused with these voltages. You asked for Vset and -Vsc

Vscan/Vsc is -189.9V
Vsch is -69.9V
Vset is the one I should have been searching for and can't find. I do have Yset which is only about 0.1V.

[tn245]

Re: Philips 50PFP5532D - X-main issue??

.. or is Vset the same as Vs? In which case it's 205V.

[tom66]

Re: Philips 50PFP5532D - X-main issue??

Vset isn't the same as Vs. Vset relative to ground should measure around 300 to 400V.

[tn245]

Re: Philips 50PFP5532D - X-main issue??

Ok, any idea where I should look for it?