50" Samsung Plasma (model number PS50Q91HD) - possible purchase

[tom66]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

A good place to check would be across that red cap.

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Photos of buffers attached.

The connectors look pretty similar to the Coppell photos...

[tom66]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

hmmm doesn't look too promising for the buffers...

Depending which pins I test on the upper board I'm getting either 0, or 5k ohms or 10k ohms.

lower board on some pins I get open loop, others 0.

If I need to replace buffers + repair ysus it's starting to get a little expensive and perhaps not worthwhile

Post pictures of your buffers, maybe you're testing the wrong places.

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

hmmm doesn't look too promising for the buffers...

Depending which pins I test on the upper board I'm getting either 0, or 5k ohms or 10k ohms.

lower board on some pins I get open loop, others 0.

If I need to replace buffers + repair ysus it's starting to get a little expensive and perhaps not worthwhile

[tom66]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

I'd throw out the Jackcon caps though! Looks okay.

Testing for shorts isn't too difficult:
http://blog.coppelltvrepair.com/2010...er-boards.html

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

OK:
Q5500
Q5302
Q5303
Q5304
Q5306

all appear to be shorted and Q5501 is blown - so the ebay auction is looking better and better...

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Check your Y buffers for shorts, it's possible they're okay. Seems like you've got a really tricky set here!

Any tips on how to check the Y buffers for shorts?

I must say, this set is really testing by confidence - I was quick cocky after fixing the 32" plasma :P

I also need to try and work out if Q5501 is the only messed up part on the Ysus or if I should bite the bullet and just order something like http://www.ebay.com.au/itm/271002634287

[tom66]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Interestingly, when replacing the bulged 680uf 25v capacitor on the Ysus board, I did notice some dark/brown patches underneath Q5501 which is now blown - so this mosfet has obviously been running hot.

From what I've read, I should be able to replace this mosfet, however will need to most likely replace both Y buffer boards?

Check your Y buffers for shorts, it's possible they're okay. Seems like you've got a really tricky set here!

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Interestingly, when replacing the bulged 680uf 25v capacitor on the Ysus board, I did notice some dark/brown patches underneath Q5501 which is now blown - so this mosfet has obviously been running hot.

From what I've read, I should be able to replace this mosfet, however will need to most likely replace both Y buffer boards?

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

I see Y-Sus repair kits like

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Well I tried a 72W halogen globe as well and same result.

Decided to bite the bullet and try it without the globe in series.

Plugged in the AC, 1 click and silence.

Tried turning the TV on and got some buzzing from the back of the set, then something went 'pop' with a small amount of smoke on the Y-main board.

Not sure what the part is in the attached photo (Q5501) - but it doesn't look so good anymore :P

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

So, you installed all new FET's, diodes and smd resistors?

Replaced only the FET's that were shorted, and the 1SS184 diodes and resistors related to those two FETs.

[scokljat]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

So, you installed all new FET's, diodes and smd resistors?

[tom66]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Found a 100W spotlight Unfortunately, when I turn the TV on I get relay clicking and the light flashes on/off inline with the relay.

The fuse for the mosfets is still good.

Ideas?

Not sure about that; try potentially with more lamps. Other than that I'm not sure...

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Found a 100W spotlight Unfortunately, when I turn the TV on I get relay clicking and the light flashes on/off inline with the relay.

The fuse for the mosfets is still good.

Ideas?

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

OK it's all back together... just gotta try find a suitable globe on the way home from work tomorrow before I fire it up

Took the opportunity to replace a bunch of shitty samyoung caps with rubycons too

[tom66]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Thinking about it, it might be better to use two 50W in parallel, or equivalent. You can use less, but you can't be sure the PSU will even start up into standby.

[tom66]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Thanks Tom - I'll assume that if I can't find a 100W globe, that two globes in series adding up to 100W would suffice?

That should be fine, just make sure not to use anything with an electronic or magnetic ballast, you -must- use an incandescent or halogen bulb.

[psmedley]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Everything should be connected and try to turn the TV on though I'd expect the TV to not power on properly with the bulb in series, but it will prevent a short from causing more issues.

Thanks Tom - I'll assume that if I can't find a 100W globe, that two globes in series adding up to 100W would suffice?

[tom66]

Re: 50" Samsung Plasma (model number PS50Q91HD) - possible purchase

Oh, and once I find a 100W globe, when I power it up, should I have all the sub-boards connects to the power supply?

Everything should be connected and try to turn the TV on though I'd expect the TV to not power on properly with the bulb in series, but it will prevent a short from causing more issues.