Samsung 50" Plasma HPT5044 No Picture

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Theres only two fuses I found on the Ymain, a green pico fuse and the glass one but they check out good. Doesn't seem to be any near the Yfr/Yrr adjusters. I was searching on the manual I found F5005 there and i think the fuses you're talking about was for the 42" plasma ymain instead?

[tom66]

Re: Samsung 50" Plasma HPT5044 No Picture

Might be, but I would expect the 50" design to be similar...

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

There doesn't seem to any fuses near the adjusters so I'm thinking its a different Ysus design.


Heres a photo of when I tested the old buffers.

Ysus + only the upper buffer board.

So I don't think the new buffers I bought are the problem.

What usually causes that split of half the screen like that?

[tom66]

Re: Samsung 50" Plasma HPT5044 No Picture

It just looks like severe overdiffusion/maldischarge.

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Is that usually caused by a bad Ysus? Why is only half the screen more affected than the other half?

[tom66]

Re: Samsung 50" Plasma HPT5044 No Picture

Yes overdiffusion/maldischarge is a Y-sus/Y-main issue -- almost always the Yfr/Yrr.

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

I probably still have a bad Ysus then. Some component near the Yfr might still be bad. It would explain why that new replaced MOSFET 88N30W shorted for some unknown reason...

I'll start testing random components around it then. Any ideas of a good place to start?

[tom66]

Re: Samsung 50" Plasma HPT5044 No Picture

Fuses, and resistors around that area. Is the 88N30 in the Yfr or Yrr areas?

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

heres photos of the Yfr/Yrr areas, there are no fuses.

The circled mosfet is the one that shorted drain-source before as soon as I tested ysus + old upper buffer (no IC) + old lower buffer

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

I got a question, Is there any difference between these two mosfets? Theyre both labeled K2837 but one is 714 and the other is 732. I was comparing the two.

K2837 714 is the mosfet right above the Yfr adjuster and my measurements on the pins are getting weird readings I dont know if its right.

Even using my Atlas DCA55 meter for it says its an unknown/faulty component.

Heres the measurements I'm getting: (On the 2K diode function)

Pins 1(black probe)-2 (red):
1.603 ohms

Pins 1(black)-3(red):
0.459 ohms

Pins 2(black)-3(red):
0.534 ohms

Pins 1(red probe)-2 (black):
0.988 ohms

Pins 1(red)-3(black):
0.427 ohms

Pins 2(red)-3(black):
1.200 ohms

I found a replacement at my local store, but its a 2SK2837. Is it the same as the K2837?
http://www.suburban-electronics.com/...SK2837/2SK2837

[Octobersky]

Re: Samsung 50" Plasma HPT5044 No Picture

A good place to buy these boards?

[awyatt2]

Re: Samsung 50" Plasma HPT5044 No Picture

i think the 714 and 732 are date codes .2sk2837 is the part nte 2970 is also the same. high speed n channel power mosfet

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Great! Then I more than likely found the problem! Just have to wait for the store to open and get this new mosfet now.

[awyatt2]

Re: Samsung 50" Plasma HPT5044 No Picture

good luck, hope u get her playing

[tom66]

Re: Samsung 50" Plasma HPT5044 No Picture

Any time you see Knnnn it is a power N-channel MOSFET 2SKnnnn
Any time you see Hnnnn it is a power NP IGBT 2SHnnnn
Any time you see Cnnnn it is a power NPN transistor 2SCnnnn

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Thanks, I'll keep that on record

[JeffJ]

Re: Samsung 50" Plasma HPT5044 No Picture

Thanks, I'll keep that on record

I am in the midst of repairing the exact same ysus. What was blown on mine were Q5306, Q5501 and Q5500. I'd also check R5508, R5509 and ZD5502 as they commonly go as well as the Fets i mentioned.

Wouldn't hurt to check before something that you replaced pops again. Or maybe they have popped now since you had failure occur again.

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Yeah I checked almost every part around that area and they seemed good.

Well I just replaced the FET K2837, and now the TV is working perfectly! =) But the light led around the power button keeps flashing randomly, dont know if its normal?

So the 1080p buffers do actually work for this 720p panel!

http://www.ebay.com/itm/251202610345...84.m1439.l2649

http://www.ebay.com/itm/400368948070...84.m1439.l2649

Spent about $60 for the buffers and $20 for the mosfets so total of $80 for this repair! (Not including the $80 scope)


This is the second plasma I've sucessfully repaired =). I think I should start learning how to solder those IC's on those buffers too.

[tom66]

Re: Samsung 50" Plasma HPT5044 No Picture

Excellent to see it working, so in the end it did turn out to be the Yrr/Yfr parts I guess? The symptoms were consistent with maldischarge or overdiffusion of the panel. You might still see a small amount of sparklies on some scenes, so tweak the Yrr if you encounter those.

They are more likely 1080i buffers, not 1080p ones. Each output on the buffer boards is tied to one line on the screen. So the buffers have 768 lines for driving a 768 line panel. A big lie with US television marketing appears to be 720p TVs marketed as 1080i, because technically, they are capable of displaying a 540p broadcast... but that's not 1080i. 1080i contains almost enough information to look like perfect 1080p (with a good deinterlacer it's almost impossible to tell the difference) and you need a 1080p panel to show 1080i...

[tom66]

Re: Samsung 50" Plasma HPT5044 No Picture

Oh, and the LED light on this series flashes whenever a button is pressed or the remote control is used. Try and isolate both to see what might be causing it.