I,m working on Zenith Z50pg10 No light on screen,has all power voltages, sound is ok green power is on I have this tv in my shop now. I replaced the Y & Z zues boards with new ones.....Same problem Thankyou my name is Steve
Televison & Video - Zenith - Z50PX2D 50 in. Plasma HDTV
Answers & Comments
Steve-
Sounds like a fun plasma. So you have Vs and Va, Y and Z replaced.. its going to come down to the logic PCB or a bad plasma panel. If you have a scope you can scope the signals over on the Y board, but that is very difficult and you need a really fast scope. It works best with a 200mhz but a 100mhz will work if you can find a point to use as a trigger. Anyways, we can get into that if you have to.
Easier stuff.. When you first kick the tv on, in a dark room, look for a slight flash across the screen. It won't light up and glow like it should, but it will give a quick flash. If you see that, usually there is something up with your Y or Z board, maybe you got a bad one. I would be that you probably have a bad logic PCB and go that route. It is the small board that drives the Y and Z through the ribbon cables, the video (LVDS) cable will feed into the logic board from your main board. You can scope the LVDS signals and see if there is "low voltage" data running on the lines, if so, you main board is likely ok. If you do see a faint glow from the screen all the time, just no picture at all, it probably is a bad main board.
Plasma's are kind of tricky TVs and there are a lot of clues we can go on. Let me know if this gives you any help, and if you do have an oscilloscope and I can direct you further. Good luck, keep in touch.
Heres a training manual for LG plasma
http://www.scribd.com/doc/7580885/LG-TV-...
basically you have to scope the signal over on the Y board and then you can use that to adjust the rampup, rampdown, stepup, stepdown, and all that kind of stuff. it will help you to get the pixel misfiring or "mal-discharge" issues fixed.. or in your case, I was suggesting to scope that point to see if you panel is even getting a drive signal. if it is, you may have a bad plasma panel.. especially if that logic board doesn't solve the issue. its really rare and I haven't really had much experience with a defective panel other than burnt up ICs at the bottom or like a horizontal line bad, but I've heard you can have issues where the panel won't charge up and work and the panel is the cause. Let me know if you have any other questions.
Steve-
the scope is the most powerful tool for plasma diagnosis and repair, but its tricky to get that signal to lock on. If you an perfect your skills here, you'll be a plasma expert. plasmas are just really complex and have tons of parts, so it takes a
long time to see all the different problems that are possible. If you can't get that signal to lock, let me know I can dig around my manuals and try to find that "trig" point to use as a reference, i think it was on the logic board. good luck