Help! Cap on Y-sustain went poof after main board swap

[Kjelds]

Hi everyone!

Really need your help on this one. Yesterday I swapped a faulty main board on my Samsung PS51D8005 plasma TV for another main board stripped from a TV of the same model with a broken panel. You can read more about this fix in this thread: https://www.badcaps.net/forum/showthread.php?t=44960

Everything went smoothly and my TV was working perfectly for 24 hours. Then when watching TV tonight I all of a sudden hear a giant POP! and the TV goes black with the audio still running. Of course I suspected a busted capacitor and when I opened it up, I quickly found a capacitor with no sides on it (see attached picture)

Replacing the capacitor shouldn't be a problem, but what are the chances that a capacitor would pop just hours after I replaced the main board?

I'm afraid that if I just change the bad cap, the same thing would happen again. So what should I do to prevent it?

Do I need to calibrate Vs and Va after a main board change and could not doing this in the first place be the cause of the busted cap?

Any suggestions would be greatly appreciated. Thanks!

[dick_barton]

Re: Help! Cap on Y-sustain went poof after main board swap

Check the voltage across it after replacing it and compare against the working voltage written on the capacitor.

[vinceroger69]

Re: Help! Cap on Y-sustain went poof after main board swap

it certainly wont hurt checking all the voltages match the panel sticker after the capacitor repair.

[ReeceyBurger123]

Re: Help! Cap on Y-sustain went poof after main board swap

Could be a bad ground, be very careful here. Remove the Ysus and inspect the grounding points-screws and connections to the chassis.

[flocko]

Re: Help! Cap on Y-sustain went poof after main board swap

I would not think the blown cap is the only component to have taken a dump on this board
Flocko

[dick_barton]

Re: Help! Cap on Y-sustain went poof after main board swap

I'd agree with you there.

[ReeceyBurger123]

Re: Help! Cap on Y-sustain went poof after main board swap

I would not think the blown cap is the only component to have taken a dump on this board
Flocko

Which as I know can be caused by bad grounds on these newer Plasmas especially samsung.

[maxvalutech]

Re: Help! Cap on Y-sustain went poof after main board swap

Difficult to see that main board swap is a cause here. I would check vs at switch on without y connected. If OK replace both the blues after checking associated components. Also bad ground could be in play as I had recent Sammy plasma and couldn't find ysus problem until I noticed in bright sunshine there was a slight oily film on the back of the board which came from the sweating of the rubbery cushions stuck to the chassis - this was causing shutdown due to interacting with various circuitry.

[R_J]

Re: Help! Cap on Y-sustain went poof after main board swap

agree with Flocko. Looks like there are two caps in parallel, if just the one went I would suspect the cap itself was the only part at fault.

[flocko]

Re: Help! Cap on Y-sustain went poof after main board swap

The oil film to the rear of the panel is heat-sink grease that is there disperse the heat from the boards rubber heat-sink pads.

[maxvalutech]

Re: Help! Cap on Y-sustain went poof after main board swap

Well it worked good in my case as it "sunk" the y-sus. As a rider to this i do add that history of the set was not known other than was wall mounted and moved between residences at one stage. Also I recall there were marks or small indents on the set to show where these rubbers were to be and the N to S one was at an angle with bottom outside the marks so....mm??

[flocko]

Re: Help! Cap on Y-sustain went poof after main board swap

It could be that the act of removing the board and reconnecting again cleared your problem, the heat-sink grease that is used is non-conducting

[Kjelds]

Re: Help! Cap on Y-sustain went poof after main board swap

Thanks for all the feedback! Unfortunately I didn't manage to get the caps I needed to day, but hopefully I'll get them on Monday.

Couldn't find any other bad caps on the board, so hopefully it's just the one. However, I'll replace both caps in parallel.

Here are some more pics of the y-sus board. Borrowed a really bad soldering iron, so had difficulties removing the busted cap hence the awful looking pin hole.

[Kjelds]

Re: Help! Cap on Y-sustain went poof after main board swap

Another thing, my local electronics dealer doesn't seem to have 630V 2.2nF polyester caps. Could I use the following in stead? https://www.elextra.dk/main.aspx?pag...7&q=2%2C2%20nf

[Kjelds]

Re: Help! Cap on Y-sustain went poof after main board swap

Hi again!

I changed the blown cap with a new one, that can manage 2000 V instead of the 630 V of the blow cap. Still no image

LED on logic board blinks on for 5 sec and off for 2 sec (service manual says this indicates DRV_RESET what ever that is?). Saw the same thing happen one time when I disconnected the Y-sus from the SMPS, so my guess is that the fault is still on the Y-sus board.

Should I also change the cap running in parallel with the blown cap even though no physical damage is visible?
Are there anything else I could check beforehand?

All advice is greatly appreciated. Thanks!

[flocko]

Re: Help! Cap on Y-sustain went poof after main board swap

If you check post 5, I told you there that replacing the cap would not fix this Y Sus board.my bet would be blown IGBTs +drivers,gate resistors and an outside chance of a few Diodes, these boards can be picked up at low cost. but remember to check any replacements for shorts, and also check your Y buffers, shorted buffers can also take out the Y Sus

[Kjelds]

Re: Help! Cap on Y-sustain went poof after main board swap

Hi Flocko,

Thanks for the reply. Yeah, I saw your post, but thought I would take a chance with the bad cap at first, which some suggested might work. And you're right, the board itself shouldn't be that expensive. I'll start looking for a replacement.

[vinceroger69]

Re: Help! Cap on Y-sustain went poof after main board swap

This seems a good price and they will post to denmark
http://www.ebay.co.uk/itm/Y-SUS-FOR-...WZtBz#shpCntId

[Kjelds]

Re: Help! Cap on Y-sustain went poof after main board swap

Great! Thanks Vinceroger69! Ordered and being shipped

[vinceroger69]

Re: Help! Cap on Y-sustain went poof after main board swap

as flocko suggests also check your Y buffers for shorts as these can take out a y sus as we dont want your replacement doing the same thing.