Samsung Plasma PN50C450 Click, clickity, click, click, click

[Michale32086]

Got a nice 50" Sammy plasma..

Upon power up, it just a bunch of relay clicks...

Pulled the Y-SUS connector from the main power board, I get one relay click and the Sammy Startup tones and 205 volts on the VS off the power PCB that drops down to about 20v after a few minutes..

With the Y-SUSo on, but the X-SUS off, I get the relay clicks and nothing else..


Checking the Y-SUS, I noticed a charred area.. (See Pic) Replace the Y-SUS with another Y-SUS and I still get series of relay clicks. Possible replacement Y-SUS is also bad...

Replace Power PCB with a couple of (pretty sure) working Power PCBs.. Still the same...

My question is, assuming that the replacement Y-SUS is valid and functional, could the charred part of the old Y-SUS have taken out something on the buffer(s)??? There are no obvious burns or chars on either buffer board..

Question #2... Would replacing the obviously dead cap on the original Y-SUS bring that board back to life?? Or is it likely the other component next to it is also fried...

[dick_barton]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

DS401 looks as though it's got a hole in it but it could just be the remnants of CS627

[JohnCT]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

My question is, assuming that the replacement Y-SUS is valid and functional, could the charred part of the old Y-SUS have taken out something on the buffer(s)???

Possible yes. Likely? Not sure.

You can check the buffers for leakage by using a dmm. I'm sure there are threads that show how to check from the input connector to the ribbons. Most buffer damage can be picked up that way.

Are you sure about your Y sustain replacement? The vast majority of this Samsung series failure is because of sustain damage, often caused by a shorted buffer. If the donor TV had a bad sustain (not unlikely), then your replacement could also be bad.

BUT, a buffer did not cause your sustain to fail. That is a 1KV disc cap, and they go for no other reason than it was just it's time. IOW, the buffer couldn't have caused this cap to burn up, but the resulting sustain failure could have damaged either or both buffer.

It's possible your original sustain is otherwise good, but most likely the exploding cap damaged some of the IGBTs. If so, just a cap won't fix it. If there are no shorted transistors, there's a good change a new (prob 270pf) cap will fix it.

John

[Michale32086]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

DS401 looks as though it's got a hole in it but it could just be the remnants of CS627

Yea, cleaned it up a bit. The remnants of the cap just brushed away. But D5401 looks intact..

[Michale32086]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

Here is a pic of the backside..

[Michale32086]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

Possible yes. Likely? Not sure.

You can check the buffers for leakage by using a dmm. I'm sure there are threads that show how to check from the input connector to the ribbons. Most buffer damage can be picked up that way.

Are you sure about your Y sustain replacement? The vast majority of this Samsung series failure is because of sustain damage, often caused by a shorted buffer. If the donor TV had a bad sustain (not unlikely), then your replacement could also be bad.

BUT, a buffer did not cause your sustain to fail. That is a 1KV disc cap, and they go for no other reason than it was just it's time. IOW, the buffer couldn't have caused this cap to burn up, but the resulting sustain failure could have damaged either or both buffer.

It's possible your original sustain is otherwise good, but most likely the exploding cap damaged some of the IGBTs. If so, just a cap won't fix it. If there are no shorted transistors, there's a good change a new (prob 270pf) cap will fix it.

John

Thanx for all the info.. Was helpful...

I am not 100% sure about the replacement Y-SUS.. All things being equal, it wouldn't surprise me if it wasn't.. My part-management capabilities leave a LOT to be desired.

I am gonna replace the cap and see what happens..

[dick_barton]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

It also appears as though you have lost a track post #5 which appears to have vaporised.

[Andrew F. Ali]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

To fully test your PSU, Connect two 120Vac light bulbs in series, disconnect the Y-SUS from the PSU and connect now the light bulbs in its place. Torn on the TV and the Light bulbs should come on and light bright and remain on, meaning Vsus is good. Measure your Va and that should be on par with what's on the sticker. Your problem most likely is the Y-SUS Bd. IGBTs are usually the culprits shorting out.

[Michale32086]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

Yea, replacing that cap didn't help.. Still get the series of clicks..

[Michale32086]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

It also appears as though you have lost a track post #5 which appears to have vaporised.

I didn't understand what you said at first...

After re-reading it, I got it that there was a trace missing...

I hard-wired it, but still got the click click click..

Looked real close and saw that one of the pads from the burned cap lifted from the PCB.. Bridged the connection.. Still got click click click..

So, either I got the wrong value of the cap...

Or the board has other issues..

[R_J]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

Have you checked shopjimmy? LJ92-01728C, Y-sus is about $25.00
Did you check the resistance across that diode?

[Michale32086]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

Have you checked shopjimmy? LJ92-01728C, Y-sus is about $25.00

Yea, I'll probably end up buying a replacement.. My main concern is that the buffers took a hit..

Did you check the resistance across that diode?

Which???

[dick_barton]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

I would think R_J is referring to the diode in front of the capacitor that blew up.

[Michale32086]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

I would think R_J is referring to the diode in front of the capacitor that blew up.

Ahhh.. That makes sense..

Could ya run me thru how to check that??

I am kinda a knuckle-dragging super glue and duct tape kinda electronics tech??

[dick_barton]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

Put you meter in diode mode and check across the two legs, meter probe on each. Take a reading and then swap the probes around.
It should read 0.5 or less in one direction and high to OL in the other. Basically you are just checking it's not short/open circuited.

[Michale32086]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

K, thanx...

I'll be at my shop in about an hour and will check that first thing..

Thanx again..

[Michale32086]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

I assume I was to check the diode with board pulled..

I get .000v both ways...

[R_J]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

The diode D5401 seems to be connected to the Vs voltage input so there could be a short on other parts that are connected to that line. maybe check all the fets on that board. if there are more parts shorted it could be cheaper to replace the board.
You can check the buffer board using your meter in diode test mode.

[Michale32086]

Re: Samsung Plasma PN50C450 Click, clickity, click, click, click

Final dispo on this..

SUCCESS!!!!

Replacement Y-SUS board fixed the problem... Display comes up like a champ..

Thanx again to all who assisted...