View Full Version : Samsung 32" LCD PS fail


DavGoodlin
12-22-2016, 11:08 AM
I had two Samsung 32" LCD sets, both dated Sept 2008. One was given by a co-worker who bought another one. the other is from a friend who wants it back if I can make it work. These were sitting in my shop for 2 years while I worked on all manner of tubed stuff. Procrastination is my forte when it comes to newer-cheaper stuff. 'specially when I never worked on an LCD before.

The first one was super-easy, with an easily spotted failure on an obvious power supply board in the center of the set.
A short-fat 150 uf, 450 v Samwha cap that was bulged, baked and burnt. A replacement is longer but fit in sideways. The set powered up and scanned the OTA channels easily, only missing a few. This one will probably be used by the kids at the PC table, to play Xbox or some crap on it, since they helped me take out and put in the screws:)

The second one looked very different inside :scratch2: with a PS board on the right side, with the PCB plugged into the display back at 8 evenly-spaced connectors. The caps looked normal and tested most, which showed low ESR. When I removed it for cap tests, a small soot mark on the display back put me in the neighbor hood of the failure.

Maybe a whole board is available online. But it looks like two surface-mount Zeners made the soot. One was shorted along with two power tab transistors (?) mounted on a heat sink, both showing an E-C short. the model is a LN32A330JIN. The PS board is a Ampower model K02P128.00

DavGoodlin
12-27-2016, 01:52 PM
I highly recommend these guys: http://www.tristatemodule.com/

The second LCD has been repaired and returned after the cost was deemed reasonable by the guy who wanted it back.

The first Samsung LCD is doing fine as the young-uns' xBox monitor but I prefer color from CRT phosphor.

I hope others find this helpful:)

Eric H
12-27-2016, 03:00 PM
I picked up a dead Samsung 32 or 36 inch LCD set (2007 date) back around 2011, found one bulged cap in the PS and replaced it, it's been working fine ever since as a bedroom set.
Not bad for $25.

mhardy6647
06-29-2017, 03:42 PM
heh-heh-heh... so...
Our daughter & son-in-law had :) an elderly (in flatpanel age... it's like dog years!) Samsung 32 inch flatpanel TV. They got it from CL some years back.

Well -- it died last week. Son-in-law reported it went pop and then wouldn't come out of standby.

Said S-I-L knows me well enough to say, "hey, if you want to check it out, you're welcome to it!". :-)

I figured almost certainly one (or more) borked PS capacitors so I said, sure, I'll take it... I figured worst case, he and I can go halfsies with him on the electronics recycling fee at their town dump!

So, yesterday, I popped the back off (easy) -- and was disappointed to find... no obviously popped electrolytics :-(

http://www.videokarma.org/attachment.php?attachmentid=195071&d=1498765252


I am not sure what my question is here. I think this is my question (!): is it worth doing any board level troubleshooting on this? Maybe check ESR on the electrolytics... and/or pull 'em out and check their capacitance values?


I am a babe in the woods with "modern" TVs -- and with soiled state stuff in general (I am a vacuum tube kind of person), so any suggestions/advice are greatly appreciated & gratefully received!

Thanks for your attention.

http://www.videokarma.org/attachment.php?attachmentid=195072&stc=1&d=1498765319

PS I have pulled out the P/S board, too :-)

EDIT:

1) The fuse at bottom right (looks like AC mains) is good.
2) That thermistor (with some of the infamous brown glue goo on it) looks kind of icky... but I don't see any signs of, e.g., overheating such as discoloration of the board under or near it.

Electronic M
06-29-2017, 03:48 PM
If you got an ESR meter use it. It is not rare for caps to die without bulging or venting.

Look for char marks on the board. That can be a sign of other issues.

Eric H
06-29-2017, 06:22 PM
Are all the Caps the same brand?

The one that failed in mine was the one oddball.

I think it was in the upper right but it's been a long time.

Celt
06-29-2017, 09:03 PM
Samwha caps are awful! Never saw one make it past two years of use. :no:

lnx64
06-29-2017, 09:10 PM
I've had some bad luck with that generation of Samsung's.. Cap went, but also took out the mainboard too with it.. Samsung wouldn't pay up, so I paid out of my own pocket for the parts.

Then the class action lawsuit happened, and you bet, they wouldn't pay me back. I was livid.

I just have such a hate for this company and their products. Only my old TV in my sig is actually decent, and even then, I'm looking for an older replacement.

Findm-Keepm
06-29-2017, 09:54 PM
Oh, how I hate those supplies. Got a good PSON signal? No? Then look elsewhere - I had a LN "B" series 46" Samsung with a bad surface mount (tiny) MOSFET that was shorted. A fellow tech led me down that path. The Mosfet toggled when the micro passed all the boot tests, and passed a 3.3V signal to the power supply to tell it to come on. He jumpered a 3V supply to the PSON terminal, and the set would come on, sort of. I got a Mosfet off an AOC board I had, and she came right up after that. Updated the firmware, and she's been reliable since.

When Samsung started buying the better caps and better boards (~2010 or so...) and got away from the Sony panels, quality went up exponentially. Ive got two other Samsungs, both with bad panels - one debonded (restaurant set, 20/7 operation) and the other is a Wii victim.

I've seen nothing but Vizios lately with the bad regulators on the main board. Getting tired of them, and all the blasted covers/screws....

mhardy6647
06-30-2017, 07:48 PM
Thanks for your input & feedback, all!

Actually I think this may finally provide me with a long-awaited excuse to acquire an ESR meter! :) Any recommendations for a good but readily available one for casual use?

I was suspicious of that big-butt Samwha cap based on its ratings... but it looks healthy enough. Maybe I'll pull it out & check it, or just hit 'n' hope & toss in a replacement and see what, if anything, happens :)

Electronic M
07-01-2017, 06:13 PM
I just ordered one of these + a case.

http://www.ebay.com/itm/12864-Mega328-ESR-Transistor-Resistor-Diode-Capacitor-Mosfet-Tester-w-Test-hook-/321963237498?epid=758803031&hash=item4af681207a:g:sBMAAOSwa-dWhWzn

http://www.ebay.com/itm/Clear-Acrylic-Case-Housing-For-Mega328-ESR-Meter-Transistor-Resistor-Tester-/172368436700?var=&hash=item2821f59ddc:m:mGsdEJfhwlE0wlWNtlJKEjw

Under $20 with case and it will test RLC values of parts, test diodes and transistors. For the last 1-2 years I've had a raw board that I made my own case for....It worked great till I set a tube chassis on it a week ago and crunched the LCD. :( This time I ordered the case in hopes it will protect it from getting crunched by setting a chassis on it..

Electronic M
07-01-2017, 06:14 PM
I just ordered one of these + a case.

http://www.ebay.com/itm/12864-Mega328-ESR-Transistor-Resistor-Diode-Capacitor-Mosfet-Tester-w-Test-hook-/321963237498?epid=758803031&hash=item4af681207a:g:sBMAAOSwa-dWhWzn

http://www.ebay.com/itm/Clear-Acrylic-Case-Housing-For-Mega328-ESR-Meter-Transistor-Resistor-Tester-/172368436700?var=&hash=item2821f59ddc:m:mGsdEJfhwlE0wlWNtlJKEjw

Under $20 with case and it will test RLC values of parts, test diodes and transistors. For the last 1-2 years I've had a raw board that I made my own case for....It worked great till I set a tube chassis on it a week ago and crunched the LCD. :( This time I ordered the case in hopes it will protect it from getting crunched by setting a chassis on it..