Tx-p42x50b Green/Red dots sparkles static!

[jonny78]

Hi guys wondering if anyone can help! I tend to stay away from plasmas as they seem far too complicated for me lol but couldn't resist this beauty for $30/£20! Now the initial fault with this was that it wouldn't power on for days! Apparently it's a common fault with this set and I've managed to fix this by replacing a little IC chip on the power supply and now it works fine but on all inputs there is green/red static sparkle that appears all over the screen (only really noticeable against a black background but it's annoying me) does anybody know what could be causing this? Now I've read that this is more than likely the YSUS board and unlikely to be the Mainboard! I can pick the ysus board up for dirt cheap! Any help greatly appreciated!

[drussell]

Yeah, those FAN6755 standby PSU controller chips at U203 on the power supply board were faulty in a bunch of models. This chip has a strange, sordid history with Fairchild being sued for patent infringement and agreeing to discontinue it, so there is virtually no admission that they ever made them at all, let alone a whole bunch of faulty ones.

The sets affected includes at least (according to the Panasonic service bulletin,) the following 42 and 50 inch models with the N0AE6JK00005 power supply boards with serial numbers below **-2560001:

TC/ TX-PR42X50
TC/ TX-P42X50B
TC/ TX-P42X50E
TC/ TX-PR42XT50
TC/ TX-P42XT50B
TC/ TX-P42XT50E
TC/ TX-P42XT50Y
TC/ TX-PR50X50
TC/ TX-P50X50B
TC/ TX-P50X50E
TC/ TX-PR50XT50
TC/ TX-P50XT50B
TC/ TX-50XT50E
TC/ TX-50XT50Y

and at least these reported by forum members:
TC-P42X5
TC-P50X5

Pretty much any set with a model with a subset of 42X5 or 50X5 may be affected and possibly any other sets that used versions this chip, Panasonic or other brands included.

As for your green and red sparklies, have you checked your panel voltages? They should precisely match what is on the sticker on the back of the panel. Incorrect voltage levels or panel drive waveforms (incorrect ramp shapes) are usually what causes sparklies. The voltages are easy to check with just a multimeter. There can be up to six or seven voltages to check on some plasma panels. Check them all, not just Vs and Va.

If the panel has many, many hours on it and is starting to degrade causing sparklies, sometimes tweaking a couple of the voltages by a couple volts can help account for panel aging but report back here with your findings before setting the voltages to anything except exactly what is printed on the panel label. Each panel is unique and the correct voltage levels vary from panel to panel, even of the same model, and are tested at the factory and the specific values printed on each individual panel label.

[tom66]

One thing to check is the brightness setting in the user menu. Try turning it down and seeing if the sparkles disappear.

[drussell]

Originally Posted by tom66

One thing to check is the brightness setting in the user menu. Try turning it down and seeing if the sparkles disappear.

Indeed, turning down the brightness setting often reduces sparklies but they really shouldn't be there at all on a 2012/13 panel unless it has very high hours on the panel or has some sort of fault, hence the reason I suggest to the OP to check that the panel voltages are correct before trying to correct the issue or minimize the symptoms, even with the user settings.

Sparklies were much more common on earlier generations of panels, regardless of age than the last few generations that were manufactured. Those giant 300 lb LGs were bad for sparklies, especially as the panels started to age, regardless of how precisely you adjust everything, what angle you hold your tongue at while twiddling, etc.

[tom66]

Originally Posted by drussell

Indeed, turning down the brightness setting often reduces sparklies but they really shouldn't be there at all on a 2012/13 panel unless it has very high hours on the panel or has some sort of fault, hence the reason I suggest to the OP to check that the panel voltages are correct before trying to correct the issue or minimize the symptoms, even with the user settings.

Sparklies were much more common on earlier generations of panels, regardless of age than the last few generations that were manufactured. Those giant 300 lb LGs were bad for sparklies, especially as the panels started to age, regardless of how precisely you adjust everything, what angle you hold your tongue at while twiddling, etc.

My thought on the brightness is many plasma panels use dithering to handle low level intensity control. The user interface brightness control can sometimes cause this to appear if the brightness level is set too high.

As far as maldischarge, the only type I've ever seen on a Panasonic is negative pre-discharge where pixels get a bit lazy as the panel ages. This means sudden changes of image can cause a few random scattered dead pixels that clear after a few frames. Sometimes, high Vs can cause blue sparkles to appear on shaded mid-intensity objects, too.

[Tech06]

I realize that this is an older thread but, I also picked up one of these TC-P50X5's recently. It originally wouldn't turn on so I replaced the U203 to fix the set. Now that I have it up and running (and mounted on the wall) I realized that the image quality wasn't great. I have tried messing with the brightness and a few other settings to no avail. There is about a 15 inch section in the middle of the panel that is darker that the top or bottom 2 inches. Also in the middles section there seem to be some blue an pink pixels scattered on the left hand side. I am wonder if the panel is bad. would you think this is IR, burn in or a bad Y sustain? If anyone has a copy of the service manual or a suggestion of what voltages to check on which board I would appreciate it.