LG plasma timing adjustment

[Proxybox]

Hi Tom66, on your guide to plasma it said you would post about adjusting timing. I did a search and didn't see it. I tried posting in that thread buts it's closed. Did you ever post instructions on this adjustment? I've tried all the options you listed to remove sparkles from my LG 50pk950-ua but without success. Adjusting any of the Va Vs or other 3 voltage adjustments as listed in the LG manual doesn't make a difference. Much appreciated. I did use a Fluke True rms multi meter.

[tom66]

Re: LG plasma timing adjustment

Timing is done on Yrr/Yfr adjustments on Y-sustain. Try adjusting those. Haven't ever been able to properly fix sparklies on LG panels though - it's a difficult one.

[Proxybox]

Re: LG plasma timing adjustment

Thanks!!! Also for moving this thread to a new thread. Sorry about mixing it up.

I did try the VSC and -Vy Adjustment on the Y-sus board. I believe that's the same as the Yrr/Yfr you mentioned? I couldn't recall the names when I responded originally but that's the ones I said were the additional 3 in addition to the Z-bias. I adjusted all those but the sparklies persist.

Additional Information: I originally ran into the common problem on the LG's where the HDMI input's would no longer work. I found a local tech who took my logic board and 'fixed' it. He told me he replaced an IC. I installed it and everything worked peachy for about a month. After that point the sparklies starting appearing. Related? Do you think replacing the logic board with another refurbished one and perhaps the Y-sus board since I get both relatively inexpensively is worth a shot?

[tom66]

Re: LG plasma timing adjustment

-Vy and Vsc are not the same as Yrr and Yfr.

Let's make sure the voltages are correct:

See here:


Check you have a PDP50R1 panel.

Page 131: Make sure Vs & Va match sticker within 1V.
Page 133: Make sure -Vy & Vsc match sticker within 1V.
Page 137: Make sure Vzbias matches sticker within 1V.

The Set_Up (Yfr) and Set_Dn (Yrr) adjustments are something we can tweak later. Ideally a scope would be used, but you can experiment with adjusting them carefully. But first, make sure all your voltages are correct.

The main input board with HDMI ports has nothing to do with sparklies. Replacing the Y-sus board will not usually fix sparklies unless something is badly wrong with the Y-sus. This usually results in a nearly unwatchable image.

[Proxybox]

Re: LG plasma timing adjustment

I adjusted all 5 voltages within the label specs. I was very precise.

After setting I noticed no.change
So.i started slowly turning pots and watching the screen with a mirror and seeing if sparklies disappeared. But nothing
On a final try, after about 4 tries, i
accidentally touched the setup pot when adjusting the last time. I tried to put it back to approximately where it started at but it was a guess. When I read I needed an oscilloscope to properly.adjust it I panicked a little. But the image didn't change or distort so in thought I was OK. However the sparklies persist.

[tom66]

Re: LG plasma timing adjustment

OK, so since the voltages are correct we can go from there.

You need a static image that shows the sparklies well. Pause a DVR, DVD player, etc.

Then adjust Set Up to the point where pixels start going DARK...i.e. not enough are lit, it will be one way or another.

Then increase it slowly until the dark pixels disappear. Choose a point that is ideally before the sparklies themselves appear.

Tell us what it looks like then...it may have a lot of dead pixels, so that is something that can be adjusted using the other potentiometers.

[Proxybox]

Re: LG plasma timing adjustment

Update: The local tech, Arturo, I mentioned agreed to take a look at my plasma. This time I took the entire TV to him to examine. In all fairness he asked me to do that the first time but I didn't want to haul the opened pdp in the car and risk breaking it but now I know that would have been ideal because each board needs to be tweaked with others when repaired for voltage adjustments. After about an hour I returned and he had it running with no sparklies. I turned it off and let it rest awhile and they still didn't return. He said that the issue was still with the logic board and that he repaired it. He doesn't speak English really well but I think he resoldered items on the board. The bottom line is it's fixed and the sparklies haven't returned in over a week of regular usage.

He showed me the boards he was sent from all over the US to repair. He's a great guy and works in a small workshop by his house in Los Angeles. I was lucky to have him local to troubleshoot the board. The other thing is he only charged me $20 since he worked on the logic board a second time. He shared his Bonanza page and he has an awesome reputation so here it is if others need board repair. http://m.bonanza.com/users/15774060/profile

I called other techs in the area and one even told me the pdp was shot and to call it a day. Another said the logic board needed to be replaced so he gave me hope but it would cost $500 but with new parts from LG and no guarantee the repair would cure it.

Thanks for all your help.