LG 42PC1D Dismantling

[raverbaby01]

hello...

my ysus board has failed on my LG 42PC1D.
i have sorced and ordered the parts online....
I'm no expert so i was wondering if anybody knew of a guide to taking the Ysus board out....
its nicely tucked away inside and i was a bit concerned about accidentally breaking something.
also...can i ly the screen down at all..? or is it just myth that it can't be laid flat...

Many thanks in advance

Dan

[Alastair E]

Re: LG 42PC1D Dismantling

Yes--perfectly safe to lay flat on the floor/table providing nothing is placing any pressure on the glass of the screen--say a screwdriver or other small object.

42PC1DA/DV is fairly easy to work on--Just loads of screws--like any plasma.

You'll need to lift up the signal block, best to disconnect all the smaller plugs from PSU along bottom edge, the earth wire from the frame near mains socket and the two aux-socket plugs in the grey wiring, one each side of the signal-block tray....

Take care of the small multi-way plugs on the Y-SUS, they are rather feeble and easily broken....

[raverbaby01]

Re: LG 42PC1D Dismantling

cool.. thank you.
i will take a crack at it and see how i get on.

[Alastair E]

Re: LG 42PC1D Dismantling

Out of curiosity, --How did you diagnose the Y-SUS was actually faulty?
--The IPM modules--those large heatsink things,--are a bit of a weak-spot on the LG sets after so many years, and some guys dont like 'em because of this...

They say, that the IPM's have a finite lifespan--then again so does most stuff these days since the RoHS Directive took lead out of electronics.
All the dead IPM's Ive seen have had the heatsink compound dried out and turned to dust--Maybe a contributory factor.....

Personally, I like these sets, and am in the middle of reverse-engineering the IPM's these models use.
Ive had some success replacing the faulty parts inside the IPM, so the next stage is complete duplication, all-be-it constructed differently with discrete parts instead of the surface-mount things the IPM uses.

Let us know how you get on....

[raverbaby01]

Re: LG 42PC1D Dismantling

well... i was really going with the majority over the forums....
no picture but sound.
blown fuse on the ysus board.

got the board out with no problem... now just awaiting a finer tipped soldering iron to tackle taking the IPM out.
the replacement IPM turned up today... along with fuse's and compound for heatsink... so just a matter of time i hope

[Alastair E]

Re: LG 42PC1D Dismantling

Take a look at the various tutorials on youtube on IPM removal--They are buggers to remove without damage to the finer print signal connections like the SUS-Up/Dn and ER-up/dn etc....

Perhaps the best way--without the correct tools--(Fine pointed iron probably wont do it) is to make a tool to do the job.

A nice chunk of solid copper--piece of bus-bar or similar with slot cut into the side heated and tinned.
--Place this over ALL the pins down one side, allow the solder to melt on all at the same time and Carefully ease that side upwards from the board.
--Do the same the otherside....

Heat conduction by the multi-layers of thick copper print--as well as the heatsink and the IPM pins makes de-soldering with std. 25/40w iron virtually impossible.

I use a 70W iron on 450 degrees (Flat out!)--VERY CAREFULLY, but this job still takes nearly an hour to do!

Use LEADED solder to first tin up the connections Before de-soldering.

BTW--Your 'new' IPM wont be new--It'll be S/H, with gawd-knows how many hours on it--New ones are not (never have been) available, only recovered ones.....
Check yours VERY carefully for shorts and tiny black marks on the 'die' chips using a Jeweller's Loupe, any found--its toast.

You can test the IPM dynamically by running a 12V 55W lamp through three of the four MOSFET 'channels' by driving the inputs and supplying 15V to the two control-chips in the IPM. The fourth needs a square-wave of 50-100KHz at 5V p/p as the driver to MOSFET is AC coupled on that one....