LG50PC1D Screen flicker

[anotherdude]

Friends tv has just gone off well kinda, at the moment it powers on but the screen just flickers and flickers with what looks likes just light, can't see any menus or anything or input from a device

bad panel?

or buffers and y sustain?

like this but without the bar in the middle

https://www.youtube.com/watch?v=en2OVVKf_Ec

after a second look it is very similar to that and does have the bars going through the screen at random intervals in different places

[tw2005]

Re: LG50PC1D Screen flicker

I'd probably start with the ybuffers. There are some smd fets that fail on those. Failing that IPMs fail on them which is more common but usually they'd short and TV would shutdown.

Check the panel voltages. Done a few 50PX5D (same panel boards I suspect)but all had shorted IPMs and Tv was i protection.

Not real knowledgeable with the LG stuff I'm afraid.

[anotherdude]

Re: LG50PC1D Screen flicker

thanks will get it tonight hopefully and start having a look

[tom66]

Re: LG50PC1D Screen flicker

You have a Y-buffer+Y-sus ER-IPM fault.

[anotherdude]

Re: LG50PC1D Screen flicker

You have a Y-buffer+Y-sus ER-IPM fault.

easy to replace/repair the parts? or are new boards the better option?

[tom66]

Re: LG50PC1D Screen flicker

What (de)soldering tools do you have?

[anotherdude]

Re: LG50PC1D Screen flicker

What (de)soldering tools do you have?

i don't have a hot air station, a sucker and braid is about all I have and a hot air gun but doubt thats going to be of any use with such small parts

[tom66]

Re: LG50PC1D Screen flicker

Not small. These parts are enormous and almost impossible to remove without a 60W+ regulated soldering iron. I would look for new board. Buffer can be repaired using average tools, but Y-sustain can't really.
It's that massive IC under one of the two heatsinks on Y-sustain that should be replaced.

[anotherdude]

Re: LG50PC1D Screen flicker

seems those ic's are just as expensive as a replacement board anyway, hmm worth the cost, £40+ for a new y sus then repairing/replacing the buffers

so if that IC has failed/failing will it have taken out the buffers too? or is it the other way round the buffers took out the IC

[tom66]

Re: LG50PC1D Screen flicker

Generally it appears the failure of the Y-sus damages the buffer board. You need to replace the SMD FETs on the buffer board - can be done with hot air (preferred) or soldering iron.

[anotherdude]

Re: LG50PC1D Screen flicker

stupid flattvparts and mistake by myself, put the model into flattvparts and seen a ysus so went to ebay and searched found one, only now that I have the tv and the back is off it's not the same model number..

boards are £100+

seems it'll be scrapped

[anotherdude]

Re: LG50PC1D Screen flicker

nvm voltages read right and can hear the click from the ysus

[Alastair E]

Re: LG50PC1D Screen flicker

At work, I have a 50PC1 with the same fault too....

Suspect the ER IPM on Z-Sus with that one.....

Just sorted a 42PC1D (sorta similar, but only 1 IPM per board), that had the flickering symptom, That was cured by repairing the actual IPM module--The ER mos/igbts were O/C.....
--Then had fun with the red-spots and software updating!

[anotherdude]

Re: LG50PC1D Screen flicker

At work, I have a 50PC1 with the same fault too....

Suspect the ER IPM on Z-Sus with that one.....

Just sorted a 42PC1D (sorta similar, but only 1 IPM per board), that had the flickering symptom, That was cured by repairing the actual IPM module--The ER mos/igbts were O/C.....
--Then had fun with the red-spots and software updating!

i had this set last year not this exact one but had all the sparklies too, are they difficult to replace?

near £70 for 2 used ipms

[Alastair E]

Re: LG50PC1D Screen flicker

IPM's are a bit of a pain--I used a good HOT iron on 450 deg C, and Leaded Solder, Braid and a sucker.

Some guys have made a jig from a piece of copper with a slot cut in that covers all the pins down one side, heated this up, tinned well, then applied to the one side of pins, while applying Light Pressure to that side until it comes free.
Process repeated other side till its off the board.....

Red-spots is cured by a Firmware-Update to the Control-board using an L.G. jig into a PC, luckly I have the kit to do it.....

Wow! £70 for 2 second-hand IPM's....
I would only sell that 50PC1D I have at work if it was working--for maybe £100!

[alanos313]

Re: LG50PC1D Screen flicker

Hi,

I've had the same problem with this model about 6 months ago, but when I replaced the buffer FETs the set only lasted a couple of hours and then blew the FETs again.

Yesterday I was given yet another one, with the same model number, and the exact same fault! I changed the FETs, and sure enough, 3 hours later the fault returned again.

tom66, could the ER-IPM be faulty even though it works perfectly for a few hours? Or is there something else going on? Seems strange to have the exact same fault on two different sets, and then not see anyone else having trouble after changing the FETs...

Any help from you guys would be appreciated.