Samsung Plasma PN58B650 Power Cycle

[unkiexeon]

Thank you for this awesome resource! I would really appreciate some additional help on this issue.

I purchased my PN58B650S1F Plasma in 2009 and just yesterday (12/26/2014), the TV went into the clicking loop with no picture; exactly as described by MyEvolution in this thread. I performed all steps as advised in this forum thread, but for the sake of being thorough I am posting my exact steps below.

I realized after adding a reply to the above noted post I should have created a new thread. I apologize for double posting and will delete my original post as soon as I have permission to do so.

This is what I have tried but I'm still not 100% sure on what part(s) might be the culprit.

When I describe LEFT SIDE and RIGHT SIDE, these sides are related to the back of the TV or while I am facing the back.

Symtoms:
1. TV will immediately start clicking when I plug it into the wall. A series of 3 clicks 1-2..3 (5 second pause repeat).
2. There is no picture or change in the screen during the power cycle above.
3. The readiness light on the front bottom right hand corner stays on (red) during the above power cycling.

What I have tried and my results:

1. I disconnected each wire harness connected to the Power Supply one at a time, then plugged the TV back into the wall. If the TV continued to click power cycle, I would re-attach the wire harness I just unplugged and unplug the next and repeat.



- I found with the above test, the Main Board (tuner board) would stop the TV from clicking.



2. While leaving the power cable going to the main board (tuner) disconnected, I jumped PS-ON to GND, VS-ON to 5V with 100 ohm resistors and disconnected the LVDS flat ribbon cable that leaves the top of the tuner board and connects to the tcon (logic board). I plugged the TV to the wall.



- The normal power quick click would occur and the TV no longer power cycles as before.
- The green logic board light now blinks slow and steady.

*** IMPORTANT ***
With the above step, I noticed a melting plastic smell coming from the LEFT SIDE and saw a bit of smoke seeping out of the top left portion of the TV (behind the main metal shield and the plasma screen backing and directly above the left wall support. Although the smell seem to emanate from near the y-main board, I did not see smoke from the board itself. As soon as a smelled the plastic, I unplugged the TV. This definitely smelled like plastic and not electrical.

3. To prevent any damage to the Y-Main and X-Main, I disconnected the power cable going to both and plugged the TV back into the wall so I could measure the power supply voltages.

VS = 201 volts DC
VA = 55 volts DC
all other voltages check out, 15v, 5.3v etc.

4. With the TV unplugged, I plugged both the y-main and x-main back to the power supply board, added the jumper to pins 3 and 4 (left set of pins on logic board). Since I was concerned with the melting smell, I quickly plugged in the tv to look for a test pattern.

- Test pattern failed - no display or change.

NOTE: I notice the normal hum coming from both y-main and x-main, but only the bottom left heat sink on the y-main seemed to get warm - all other heat sinks were cold.

5. I unplugged the TV and the power cable going to the y-main and checked for continuity across the green inline fuse (upper right hand corner for the y-main - looks like a resistor).



- There is NO continuity (no tone) across the green fuse.

NOTE: Checking for continuity across the green fuse on the x-main checked out (tone).

6. I have checked all removable fuses for continuity and all have checked out.

Based on my testing, I would think the y-main and Main Board is bad, however, I need to know if the green fuse should have continuity or if this is more like a diode, where I wouldn't hear a tone when testing with my meter.

Are there any other tests I can do on each component to be sure I order all the parts I need?

Thank you for your expertise. I look forward to getting my TV fixed.

[tom66]

Re: Samsung Plasma PN58B650 Power Cycle

Nice pictures and good diagnosis for now. That fuse should test as a short. Can you try checking from each end of the fuse to the chassis for short circuits? Use the ohms range.

[unkiexeon]

Re: Samsung Plasma PN58B650 Power Cycle

tom66,

Thank you for the quick reply and suggestion.

Checking for shorts - meter set to auto range ohms:

Y-main Green fuse:
ground -> right side of fuse :: 2k
ground -> left side of fuse :: 30M (high resistance)

X-main Green fuse (fuse is standing vertical on the board):
ground -> right side (top) of fuse :: 11.5k
ground -> left side (bottom) of fuse ::11.5k

Since the caps seems to be taking a charge from the my meter, I held the probes in place for about a minute and waited for the reading to settle.

Thanks again for your help. I really appreciate it.

[tom66]

Re: Samsung Plasma PN58B650 Power Cycle

Well, that is not showing a short. Could it be that you smelt a fuse failing? Maybe it's worth trying with another fuse. I'd like to see what the fault might be first, though. Any signs of burn marks or damage on other components? That fuse is probably for the 15V supply, which powers a lot of things.

[unkiexeon]

Re: Samsung Plasma PN58B650 Power Cycle

tom66,

I did remove the screws for the y-main and y-buffers so I could swing the board out and inspect the back. There are no visible signs of damage on the backside or front. As I stated before, the only time I saw smoke was after the first time I jumped the PS-ON to GND, VS-ON to 5V with 100 ohm resistors and plugged in the tv (30 seconds). Since then I've been caution leaving the TV on longer than 10 seconds while the y-main and x-main are plugged into the Power Supply. Further tests with the resistor jumpers in place would also produce the burning plastic smell near the upper left portion of the y-main capacitor (see attachment).



As a quick test I used alligator clips to jump/bypass the green fuse on the y-main but used a small 100 ohm resistor in parallel and in place of a fuse. I know this is risky and I should use another fuse. Turning on the TV with the PS-ON to GND, VS-ON to 5V with 100 ohm resistors, this had no effect and the TV would not turn on or give me a test pattern with the pins 3-4 jumped on the Logic board.

NOTE: In my original post, I forgot to mention, when the TV picture originally went out, I heard a pop-fizz, then the TV began cycling to power with no display.

Based on my tests, I still believe the Main Board and the y-main have been damaged or at fault for the set not functioning. I just find it odd that both went and hope nothing else has been damaged. I would like to be as thorough as possible and perform any/all tests to be sure I am getting the right parts.

Thanks again for your help.

[SewnNsilent]

Re: Samsung Plasma PN58B650 Power Cycle

I know this is an old post, but did you ever figure out the issue? I'm having the exact issue (minus the burning smell and smoke). Seems like all of the other threads troubleshooting the power cycling ends with a positive pattern test and (probably) a bad main board. Not sure what the next steps would be if the pattern test fails.

[unkiexeon]

Re: Samsung Plasma PN58B650 Power Cycle

@SewnNsilent

In the end I determined several components had failed in my Plasma panel but I am happy to say I have successfully repaired my Plasma panel and it continues to work operate beautifully.

By performing the tests noted in my original post and by followingthis forum thread I determined the following components failed.

- Y-Main
- Y-Upper Buffer (upper long thin boards vertically aligned on the TVs back left edge)
- Main Borad (tuner)

I followed this youtube video to test my Y-Upper and Y-Lower Buffers and determined only the Y-Upper Buffer was bad or failed. After some research I found it was not uncommon for the Y-Main to blow/fail when one of the Y buffers blow/fail. Some people have stated you should replace both buffers (upper and lower) even if only one has failed. I did NOT replace both buffers and only the one that failed. Maybe it was a gamble, but trusted the Y-Lower Buffer was fine which in the end proved my judgment was right.

All-in-all the Y-Main and Y-Upper Buffer were relatively cheap to replace ($49.99 and $28 respectively) where the Main Board (tuner) was the most expensive ($91.89). I ordered the Y-Main and the Main Board (tuner) from tvpartscentral.com and although the Y-Main board I originally received was physically damaged, they were relatively quick to resolve the issue and sent me a replacement. I can't remember where I purchased the Y-Buffer, but do remember the one I received was a different revision and actually had fewer capacitors on it. I was concerned with using a different revision especially because I was not replacing the Y-Lower Buffer, but in the end found this was not an issue and performs beautifully.

Note: I determined it was safe to use the Y-Upper Buffer by contacting the Samsung Repair service. I was able to speak with a local certified repair tech over the phone and explain the differences between my original Y-Upper Buffer and the revision I received and he assured me there would not be any issues using the revision I received and in fact was very common to do this as long as the cross-reference matches.

I installed all parts mentioned above at the same time and did NOT replace one at a time and test. I did not want to risk having one of the components I tested as being bad cause one of the replacement parts to fail. Upon turning on the TV I heard the Samsung startup tune and saw the Samsung logo on screen. Woohoo! Because my Plasma panel was not connected to a cable source, I turned off the panel and plugged in my Google Chromecast and connected to Netflix to verify the replacement Y-Main (tuner) was working. I never did attempted a TEST pattern since I could see the panel was working.

To date, my Plasma panel continues to function and the image is as beautiful as it was the day I bought it. Funny thing is, I used to have the notorious Samsung buzzing/hum sound many have reported with these models, but after replacing the Y-Main I no longer hear this.

In the end, I'm not sure why so many parts failed in my 5 year old Plasma, and when I asked Samsung how this could happen on a $2000 Plasma, they replied with "It's normal wear-and-tear". Really??? That most ridiculous response has really changed my opinion of Samsung and in the future know I will be looking at other manufactures when making a new purchase.

I hope this helps and that I answered your question.

[SewnNsilent]

Re: Samsung Plasma PN58B650 Power Cycle

Thanks a lot for your response! I will check out the links you provided. I had just received the tv for free from my dad before I my previous post and had not done much research on the parts. Once I realized that the individual boards weren't all that expensive, I was thinking about ordering what ever I could find and throwing it in there. A couple hundred bucks for a 58" in tv is still a pretty good deal! But now I won't feel like it's unnecessary! Thanks again!