Samsung plasma PN50b430 maldischarge

[gdawg]

I was hoping to get some help on a Samsung 50" plasma with no video-just maldischarge looking screen. I always appreciate any input on repairs and am saying thank you in advance.

Here is what I have. It had a shorted x or z board which ever Samsung calls them, so I repaired it at component level. I then found I had a few shorted components on the y sustain, so I replaced those. The tv would shut down before and now it stays up and running. I get the flashing led on the logic board and the Samsung chime when I power it up. The panel primes and get very light static look on the screen. I went into service mode and the picture changes colors and you can see the scrolling bars but no menu or any sort of image.

I will include pictures so you can see the screen. I was going to guess the y sustain but don't know if I should have a menu displayed so then I thought maybe the video board is the problem. I did have a spare logic board, but no change. I am sure when you see the pictures, it will be pretty obvious what I need but wanted to get some more experienced advice

[gdawg]

Re: Samsung plasma PN50b430 maldischarge

I forgot to mention, all voltages are matching what the sticker on the panel shows.

[gdawg]

Re: Samsung plasma PN50b430 maldischarge

Any help on this one, I feel like its a sustain problem but I thought when you jump 3-4 on the logic board you get a readable osd. Mine as you can see is total red or blue only when its in the service state. Both sustains are making the usual hum noise and all panel voltages are fine. When its not in the service mode, then the screen primes and you get a very faint static look but no osd at all. Some times you can see the osd but its as bad as the screen. Thanks for any input on this. Its a pretty nice plasma, and I would like to get it working. Thanks again for any help on this. I dont have a scope, just a nice Fluke dmm.

[RCA2000]

Re: Samsung plasma PN50b430 maldischarge

I would look farther on the Y-Sustain board--since it DID have some bad components. Likely something else is STILL bad there..

Maybe you should try and grab a known GOOD Y-Sus baoard...and see how that works. because if you foi NOT get clean red, green and blue alternating rasters with the TP jumped...it rules OUT the signal board and all before it. Your raster looks a LOT like a bad Y-SUS board to me...

I do NOT believe you will get OSD with the TP jumped--alternating colored full rasters I think.,.

[gdawg]

Re: Samsung plasma PN50b430 maldischarge

Thanks, I was leaning toward the y sustain but wasn't sure about the osd. The tv stays on and did not find anything else shorted on the y board. I did the usual test on the buffer and its not shorted. I guess I will start the hunt for a y board and assume there is something not working right on that board. I am pretty good about finding shorted components, but components not working right is a different story. Thanks again

[ReeceyBurger123]

Re: Samsung plasma PN50b430 maldischarge

Xmain is faulty, these use combined ERC so a bad Y can kill the X so check the Xmain output.

[gdawg]

Re: Samsung plasma PN50b430 maldischarge

Well. I must have missed something on one of the boards. I know the X board had a few shorted fets and diodes and because they are linked I checked the y board and found two shorted fets and checked about everything else including cold solder joints and nothing apparent. This one is driving me a little crazy, cause I dont know which board to point the finger at. At least I got it to power on and stay on, so I am making progress. Any ideas what I should be looking for??

[Alastair E]

Re: Samsung plasma PN50b430 maldischarge

Check/replace the driver-chips and series-resistors for each and every IGBT you replaced/found short.

[gdawg]

Re: Samsung plasma PN50b430 maldischarge

Xmain is faulty, these use combined ERC so a bad Y can kill the X so check the Xmain output.

I am not real knowledgeable on some of the test points. Where do you ck the output, cause I believe the only test point on the X main is Ve and that one is with in .1 volt of the panel sticker. I dont have a scope so is there any place else to test???

[gdawg]

Re: Samsung plasma PN50b430 maldischarge

Check/replace the driver-chips and series-resistors for each and every IGBT you replaced/found short.

I did check all the resistors off the igbt's and I checked the drivers and all the readings seemed ok. I should say the driver chips were not shorted and all leads of the drivers had resistance in reference to ground. The hard part is both X and Y main have the normal hum and voltages are fine. I sure would like to fix at component level but I am starting to get a little worried, might be over my head. Sorry my terminology was wrong, I guess they are igbt's and not fet's.

[gdawg]

Re: Samsung plasma PN50b430 maldischarge

I was going to replace all the igbt's and diodes on the y sustain board and i did something stupid. I removed the transistors and took a quick glance and thought they were the same as the x main. After pulling them off, I noticed one was a RJP63F3 and the other was a RJP63K2 but didn't notice where they were removed from the board. I pulled data sheets and hopefully I can use the same part number for both, but not sure which one to use even if thats possible. I was relying on someone's expertise on data sheets. If not then I guess I have a 50% chance of getting it right. Also, I could not find a service manual for my model. There are a lot of variations on this model and mine is as pictured at the beginning of the post

[Alastair E]

Re: Samsung plasma PN50b430 maldischarge

63K2 can be subbed by 63F3A but Not the other way round...

63K2 is a fair bit slower--and older part--and has higher V-On and lower current rating.

[gdawg]

Re: Samsung plasma PN50b430 maldischarge

63K2 can be subbed by 63F3A but Not the other way round...

63K2 is a fair bit slower--and older part--and has higher V-On and lower current rating.

Thanks, I really appreciate the info I will order the 63F3a. Not even sure it will fix my problem, but I figured I would invest another $20. or so. Boards on ebay are $100.00 or better and not even sure this will fix it. It will keep me out of trouble on the weekend though. Thanks again