zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

and i kinda see in 4th and maybe 3rd


pic where you say there may be a distinct horizontal area but its not there in the first 2 pics ....and its from the same tv...so ....

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

i do remember way back that there was a way to test for shorted buffers and i believe 1 or 2 were shorted in some combination between tvs .....does that help at all?? and thats why i bought 2 replacements from shop jimmy years ago..i have all my boards marked from shop jimmy and ones i got from ebay....

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

update....hope this info will help...did some tessts

unplugged y buffers from y and display does not change at all on both tvs....also did temp test on all z and y heat sinks after tvs on for 20min

z....heat sink 85deg f
y..hsinks.....1....89deg......2....136deg

basically same readings both tvs

i then unplugged z power source and picture went totally black both tvs

any ideas?

[tw2005]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

?

........................................................................................................
You have 2 sets of buffers, if it's only one board dragging the ysus down then you may get lucky and get half a good display isolating and swapping the buffer boards..........................................

update....hope this info will help...did some tessts

unplugged y buffers from y and display does not change at all on both tvs....also did temp test on all z and y heat sinks after tvs on for 20min

z....heat sink 85deg f
y..hsinks.....1....89deg......2....136deg

basically same readings both tvs

i then unplugged z power source and picture went totally black both tvs

any ideas?

or check the voltages on the ysus with the buffers removed and then with them connected

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

ok.....i think

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

ok.....when i get time i will try.....but i know im getting voltages to y because i get voltages from ps and heat sinks are getting hot......r u saying check voltages going to buffers?....when connected?

[tw2005]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

ok.....when i get time i will try.....but i know im getting voltages to y because i get voltages from ps and heat sinks are getting hot......r u saying check voltages going to buffers?....when connected?

Well to be honest, I'm not 100% on the LG/zenith but i was thinking check Vs, Va which comes from the PSU and on the Ysus Vsc(vscan) and -Vy which are generated on the Ysus and I'd try it without the buffers and then with for the ysus but someone out there probably has better knowledge if this is correct or a good idea.

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

well at this point im confident its bad y board and or bad buffers......i ordered a y for 25.00 shipped.....ill let u know......i think the 2...ys i bought 3yrs ago were defective...but its a guess...we will c

[tw2005]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

well at this point im confident its bad y board and or bad buffers......i ordered a y for 25.00 shipped.....ill let u know......i think the 2...ys i bought 3yrs ago were defective...but its a guess...we will c

Find out i guess, I was hoping you'd try just the upper buffer installed on it's own, then swap if no good then same for bottom but it's not like i know these thoroughly.

So if the next one does the same, what then? assume all 3 are bad or are all 3 good?

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

i did just have upper connected...no change both tvs

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

yes all 3could be bad or good....and a bad panel

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

this model tv if you google it is such a common issue...zenith was sued for it.......so im hoping its just a bad y

[tw2005]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

fair enough and good luck, this time maybe

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

another update i get 0v when testing 5v pin going to y buffer...plugged in and unplugged

?


also what are the boards on bottom....z buffers?

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

i have never seen any reference to the horizontal boards mounted on bottom...not sure what their function is

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

and when i test vs i get 180v per cheap harbor freight meter......panel says vs-193v

is that ok?

and when i check 5v pins going to z from y i get 0v

maybe y board 5v circuit is bad?

[freakaftr8]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

Bottom boards are X buffers. These operate the vertical address..doubt it's your problem.

[tw2005]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

and when i test vs i get 180v per cheap harbor freight meter......panel says vs-193v

is that ok?

and when i check 5v pins going to z from y i get 0v

maybe y board 5v circuit is bad?

So you could isolate the power connector from the Y and measure the resistance on the 5v rail at the Y and see if it's shorted, could also confirm you see 5V from the PSU as you power up with out the y connected?

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

i do believe i have 5v coming from ps but i will double check that when i get time....i did check some pins today and i do remember seeing 5v from ps

but for sure no 5v from y to buffer and no 5v to z whcih on my tv comes from y

all fuses on y are good...i checked the 2 large fuses and the small surface mount fuses 4 of them...all good

one question though...is the 180v actual vs within tolerance of 193v vs spec

thats over 5% difference is this ok or would create a noticeable problem?

[shelby5041]

Re: zenith Z50P3 PLASMA TV screen issues pink and purple grainy no image

and thanks freak....i didnt think the bottom buffers were an issue qas my research found nothing about them....mostly bad z y and y buffers and mostly and from this list the y board is by far the most common issue on this tv