lg 60pz550-ua erratic horizontal pink lines over image

[smartjohn]

Hello again old friends! I am perplexed with this set. The mainboard was reballed to fix the known issue of HDMI port loss. When it came back from service I reinstalled it and now have the attached image. The image is there but it looks to be some type of Z-sus problem. I have checked and rechecked and replaced the LVDT cable between the logic and main board with no luck. And yes, the inductors on both the Y-sus and z-sus have been re-soldered with clean new 60/40 material. All voltages match the panel label Vs=202, Va =55, Vzb = 110 (it was at 115 and was adjusted down) Vy = 180, and Vsc =150. I did run the jumper test on the logic board and got all clean color screens and the traveling white bar. I am at a loss looking for any suggestions!! Thanks for any help!! Also, I sent the board back to the shop who did the re-ball and they confirmed it was working perfect in their test set!!!

[Biruslapio]

Re: lg 60pz550-ua erratic horizontal pink lines over image

if the set works with the jumper test on logic board, it is the lvds connector/connection problem or main board.
These models are known for terrible bga problems on the main chip, so ask the shop to prove it is working with your board, because it does not makes sense why it would only work in one tv and not in the other which can reproduce test patterns just fine.

[smartjohn]

Re: lg 60pz550-ua erratic horizontal pink lines over image

Right, I agree. I am just going on his word that it worked. I am trying to eliminate any other Z-sus / Ysus possible cause that might result in something similar. I saw a number of posts on this model talking about "mal-discharge" with similar screen pictures. Not sure exactly what that term means.

[Biruslapio]

Re: lg 60pz550-ua erratic horizontal pink lines over image

if the test patterns run without issues, it cannot be mal discharge or any problem with the sus boards.

[smartjohn]

Re: lg 60pz550-ua erratic horizontal pink lines over image

Another peculiar issue is that this TV powers on as soon as I plug it in. In the past this has been a symptom of other issues I have felt with. Does that sound normal to anyone else?

[Biruslapio]

Re: lg 60pz550-ua erratic horizontal pink lines over image

the tv will do that if there is no mainboard connected(auto_gnd pin at 5V)

[Davi.p]

Re: lg 60pz550-ua erratic horizontal pink lines over image

I'm no good with plasma, but my guess is it has no sense to trim some voltages, the trimmers are not there to trim them after sale, i often read techs do that but usually they don't solve, why don't you check capacitors on the psb or sustain boards?

[smartjohn]

Re: lg 60pz550-ua erratic horizontal pink lines over image

Sure, worth a try but I don't see any physical indications for bad caps (no bulging, no leaking substance, etc). My next effort will be to apply a heat gun to the main board chip under the heat sink to see if the picture ever goes to normal. I am running out of ideas on this one!! I do have a scope so I may look for a more technical doc from LG that lists some acceptable waveforms for the main board....

[Davi.p]

Re: lg 60pz550-ua erratic horizontal pink lines over image

A flat and clean condenser is not absolutely a sure good condenser, if you have no ideas why don't you control those condensers?

[tvtimmy]

Re: lg 60pz550-ua erratic horizontal pink lines over image

It's 1000% the mainboard. If the display is clean while running the test patterns, the mainboard is the fault. Dont screw with any voltage changes.

[nomoresonys]

Re: lg 60pz550-ua erratic horizontal pink lines over image

^^I agree 1000%, mainboard IS the problem.

[smartjohn]

Re: lg 60pz550-ua erratic horizontal pink lines over image

You are all convincing me even more that it's the mainboard. I re-ran the logic board jumper test just to satisfy my sanity and same perfect result! So all other components are working fine. I am asking the original repair center for a refund and hopefully will be sending the board to Nick's TV in Arizona. This I what I get for trying to save a few bucks!!!

[nomoresonys]

Re: lg 60pz550-ua erratic horizontal pink lines over image

Nicks is a good choice. With the q-led tvs being around $350 for a 65 inch at the super sales going on or coming shortly, I would just have a hard time investing in the 10+ year old plasma, I would be always wondering whats next to go wrong.

[Davi.p]

Re: lg 60pz550-ua erratic horizontal pink lines over image

i forgot the auto test, so i also bet for the main board , the problem with LG mainboards i think are some lot of defective chips, it is not the solder probably.. it's a matter of bad contacts under the chips.. no luck with any kind of rework job.. my guess..

[smartjohn]

Re: lg 60pz550-ua erratic horizontal pink lines over image

@nomoresonys point well taken! The set is my son-in-laws and he loves the plasma depth of contrast and screen speed for sports. Although the newer leds and OLED's are pushing the comparison. I think I can get the board reworked for about $80 - 90 US, so we'll see. But if it's more than that he will probably vote for a new TV. He has the LG 60 and a Samsung 60 mounted side by side so he doesn't miss a play! My daughter wanted him to trash both plasmas and buy one 75 inch 4K but I don't think he's going to comply!

[nomoresonys]

Re: lg 60pz550-ua erratic horizontal pink lines over image

that 75 sounds good, I would just put 2 games on split screen and cast off those energy hogs. Last plasma I messed with a few months ago, just for fun, fought the z/x board all the way, needed all the igbt's replaced a diode and several caps, was a pain all the way, nothing is as easy to get out as the lcd/led tvs, so got that board fixed, just to discover that the buffer boards each had blown chips, not visible, could only tell by testing for shorts, so rather than try to track down the scarce boards that they want silly bucks for, I just called it quits, don't think I will mess with plasmas anymore, have never liked them since I tore one down many years ago, it had 3 big loud fans and LOTS of boards and weighed a ton, theyre too damn heavy and run too hot, no fun.

[tvtimmy]

Re: lg 60pz550-ua erratic horizontal pink lines over image

I only deal with Samsung, LG, and Panasonic plasmas from 2011-2013. They are way easier to fix than the "tanks"(2003-2010) they all used to make.

[nomoresonys]

Re: lg 60pz550-ua erratic horizontal pink lines over image

^^+1000, those older ones are horrendous.

[Biruslapio]

Re: lg 60pz550-ua erratic horizontal pink lines over image

I love plasma and have bought and fixed many in the span of 5 years, but now I'll only bother if they are full hd or a very rare model, if there's issues like these that it's basically irrepairable and unable to guarantee future proof just drop it, have seen for sale some 60PX950 around here and all had mainboard problems, buying a used one (and who knows how long it will last) costs half of what the TV was worth, nope.

[nomoresonys]

Re: lg 60pz550-ua erratic horizontal pink lines over image

Indeed, the parts are just not readily available anymore, I'll be damned if I'm paying 100 bux for buffer boards that will probably be shorted because the seller is either too lazy to or doesnt know how to do a simple test for shorts, plasmas did and do serve well but when they get long in years, all the running hot that is inherent, takes its toll.