lg50pc1d advice, slight flicker

[wills123]

so i picked up this with the common white bar on screen fault really cheap, stripped it out and sure enough 1 mosfet on lower y buffer shorted,
i replaced all 3 fets and also 15 caps on the psu that wernt healthy looking.
its been running for 3 days , picture looks good no sparklies or anything but every now an again the theres a slight/brief flicker to the screen, particulary during adverts that have a lot of white in them!
Should i replace the mosfets on the top buffer too? after all theyve done the same amount work as the lower ones so one cud be failing.
Or could it be a ysus fault?

thanks in advance for any help/advice

[sordids999]

Re: lg50pc1d advice, slight flicker

Posting pictures of the back of your tv showing the boards with clear pictures may help you more with fixing your problem

[Alastair E]

Re: lg50pc1d advice, slight flicker

In the very hot weather we are having--you are probably suffering with an IPM intermittent fault. This is well known on those PC1DA chassis sets (V8/X3) for these to fail either short-circuit or go intermittent with a slight ticking noise while flickering.

They run extremely hot--Normally, so in the extreme temps we are having now--well, --even hotter! Heat is the enemy with Semiconductors as well as all other general electronic parts like caps.....

Its 28 deg C in my living-room at the mo, due to top floor and tin roof, I dread to think the temp inside a 300-500W plasma set after a few hours if I was to run one!

[wills123]

Re: lg50pc1d advice, slight flicker

thanks alistar, is that buffer ipms or the ones in the ysus itself? i can get secondhand boards for this so cheap that i feel its worth repairing as it does look good in my living room
i dont see the need for pics sordid 999 its a very common set an layed out the same as all plasma tv's.
do you think its worth replacing the upper buffer mosfets anyway alistar? from the research i done there a common fail, maybe i cud put little heatsinks on them, or wire the fan direct so it runs constant cooling it more?

[Alastair E]

Re: lg50pc1d advice, slight flicker

The relevant IPM's are under the big heatsinks of both the X and Y-boards--There are only IPM's used on SUS boards, nowhere else in the set.

50" has 4 IPM's. It could be any of the four, although the top ones (ERC) IPM's are most likely to cause flicker The SUS IPM's tend to go short.

Worth changing all the small SM (33uF and 68uF) caps around the DC-DC converter stages of the Y-SUS, as this supplies the drive-voltages for the IGBT's inside the IPM's.
--Use 47uF and 100uF 35-63V normal wire-ended as replacements.

Wouldnt bother with the MOSFETS on buffers TBH, easy fault and easy/cheap when they go. IPM failure however is both difficult and costly to repair.

Defo worth adding fans to all the IPM's and making sure all the panel voltages are correct. a Vs too high can easily stress/overheat an IPM.....

[wills123]

Re: lg50pc1d advice, slight flicker

great info thank you very much, will look into replacing them an upgrading the cooling of them, i will get those caps changed too, forgot to say i already tested the voltages an they were good.