Samsung Plasma TV - Worth Repairing?

[MrKarst]

Hello!

I have a Samsung plasma TV, model number HP-T4254, manufacture date Sep 2007. A week or so ago, the screen turned off by itself and some clicking noises came from the TV. We disconnected power and it started working fine again. Then the problem started occurring more frequently to the point that the set was not really usable.

I did some research and learned that one possible source of the problem is bad capacitors, so I followed the instructions I found in a few posts and videos to open the TV and locate the power supply. I took the power supply out of the TV and examined all the caps very carefully and none showed any signs of bulging, cracking, discoloration, etc. I carefully cleaned as much dust as I could from the power supply and other internal components, put everything back together, and tried to power on the TV.

There was a loud crackling sound and a burnt electronic smell and I turned power off immediately. I thought perhaps one or more of the caps had now blown, so I opened it up again but everything looked fine based on visual inspection. I hooked up power again and now I get a repeated series of clicks (I guess that's the relay trying to power up the set) but no more loud crackling sounds. However, the set will not power on.

Based on what little I know and have learned, it seems like perhaps the entire power supply needs to be replaced. Either that or someone with more skill than I have would have to test individual components on the power supply to find the problem. Both of these options seem like they will cost more than $100 (I found USED power supplies for this TV online for $103 and up, all from vendors in China).

My basic question is this: Is the TV worth salvaging? Or would I be better off putting the money toward a replacement TV? I really hate the idea of trashing something that is fixable, especially electronics.

Any advice or suggestions will be very much appreciated.

[tom66]

Re: Samsung Plasma TV - Worth Repairing?

Sounds like a sustain board failure. Yes it is fixable.

Unplug the board on the left hand side of the TV (when looking from rear and while off!) That is the Y-sustain. If the TV now powers up with sound, the Y-sustain is failed. Then plug in the Y-sustain again and unplug the Z-sustain, which is on the right.

Post a picture of the back of your TV, so we can help you locate the boards.

[MrKarst]

Re: Samsung Plasma TV - Worth Repairing?

Thanks for the reply! I am posting a picture, as requested.

So if the TV DOESN'T power on with the Y-sustain disconnected, does that mean the Y-sustain is OK? And I assume if the Y-sustain is OK then I do the same procedure to test the Z-sustain? Are these boards readily available to purchase or order? Any idea how much they cost?

One last question: Any idea what the crackling/popping sound and associated burning smell might have been? That just sounds bad to me, like something is really fried.

Once I'm sure what the Y- and Z-sustains are, I will test this out. Thanks again!

[tom66]

Re: Samsung Plasma TV - Worth Repairing?

Well, it confirms that the Y-sustain isn't causing the problem, but it could be faulty in another way. For now, it's good to focus on the original problem.

Semiconductors in these TVs deal with high currents and voltages and when something goes wrong a lot of energy is available to damage the component which can cause a nice "pop".

See my guide: https://www.badcaps.net/forum/showpo...42&postcount=4

I've posted an image with labels of the boards.

[MrKarst]

Re: Samsung Plasma TV - Worth Repairing?

Thanks Tom!

OK, so to make sure I'm doing this right, to disconnect the Y-sustain board, I just unplug the wire bundle in the upper left of it that goes to the power supply, right? And if the Y-sustain seems to be OK (if I don't get sound when it's unplugged), then I will do the same procedure with the Z-sustain.

Once I get your confirmation of how to disconnect the Y-sustain board, I will give it a try!

-Kevin

[tom66]

Re: Samsung Plasma TV - Worth Repairing?

Thanks Tom!

OK, so to make sure I'm doing this right, to disconnect the Y-sustain board, I just unplug the wire bundle in the upper left of it that goes to the power supply, right? And if the Y-sustain seems to be OK (if I don't get sound when it's unplugged), then I will do the same procedure with the Z-sustain.

Once I get your confirmation of how to disconnect the Y-sustain board, I will give it a try!

-Kevin

Yep, just the power connector, the one with the thick multiple leads.

Give the TV a good five minutes to discharge any capacitors. (Although in my experience most plasma TVs discharge the capacitors in a few seconds, when they are faulty you cannot guarantee this will happen.)

Be careful as while running, exposed parts of the Z-sustain have in excess of 200V on them and on the Y-sustain it can be as much as 390V.

[MrKarst]

Re: Samsung Plasma TV - Worth Repairing?

OK, thanks for the tips. I will try this and report back!

[MrKarst]

Re: Samsung Plasma TV - Worth Repairing?

OK, so I have confused myself somewhat.

I disconnected the Y-sustain board, then hooked up only the power cord and the cable cord. I guess the problem is that since the screen is not working I can't tell what source the TV is set to. So I just used the buttons on the side of the TV (not the remote) to turn the volume up (since I would have normally had the volume at zero since we use a receiver for sound) then pressed the source button repeatedly with a long pause in between presses. My thought was that I would eventually hit the cable input and if there was sound to be created it would happen. I pressed the source button at least twice as many times as necessary (2x the number of inputs) and never heard sound.

I think plugged the Y-sustain board back in and tried the same thing but still heard nothing. Am I misunderstanding something simple?

I should also point out that through the entire time there was power to the TV, there was a consistent pattern of clicks coming from the vicinity of the power supply board.

Any further advice will be most appreciated! In particular, I'd love to know how to provide a reliable source of sound to be sure the sound is working or not.

Thanks again!

-Kevin

[tom66]

Re: Samsung Plasma TV - Worth Repairing?

The clicking is because the power supply is shutting down due to overload; either from the sustain boards or something else. If you hear clicking, then there is still a problem.

Try with the Z-sustain next.

[MrKarst]

Re: Samsung Plasma TV - Worth Repairing?

Do you think the source and volume buttons will work if the screen doesn't come on? Otherwise I don't know how I can test if the sound is working or not. :-/

[cadiman]

Re: Samsung Plasma TV - Worth Repairing?

When I plug these in you hear the logo sound upon the center blue light/button lighting up.

Also when you turn the tv on/off there should be an audiosound series of beeps melody.

You will hear the y and z boards "running", or not.

I use dvd player with "y" adapters and run audio/video in to all of the video/audio inputs (rca) so sooner more than later you will find audio sound and know you have a signal.

I have had problems with every board on these tvs. Mostly y drive with buffers second.

I would really focus on what the power supply is doing.

When does it click on then off.

Listen for y and / or z boards running.

I have a few posts here for using a neon tester to check for the needed high voltage at the buffers. be careful here!

good luck

[MrKarst]

Re: Samsung Plasma TV - Worth Repairing?

Thanks for the additional info. I know the sound you're talking about when it powers on and off and it is NOT making those sounds anymore.

At this point, I think the diagnosis and repair are beyond what I have the expertise and time for, so I am going to see about getting a quote from a repair shop. My concern is that it will cost more than the TV is worth to me. If that turns out to be the case, I will look for options other than sending it to the landfill.

Thanks again for all the help!

[tripps09]

Re: Samsung Plasma TV - Worth Repairing?

I'm very happy I searched and stumbled upon this thread!

I have a similar TV but in a 50" (Samsung plasma) and the sound works but video doesn't.

Troubleshooting steps I've done:

Unplugged top buffer board. No video, audio works.

Unplugged the bottom board. Still no video, audio works.

Unplugged z-sustain board, turned TV on. I could hear the audio.

Unplugged Y-sustain board, turned TV on. I could still hear the audio.

On the y-sustain board, closest to the power cable, there is a capacitor with the top bubbling up and a black dot on top.

After the TV is on for ~20 minutes, I turned it off and after 5 minutes I felt the heat sinks.
Both heat sinks on the z-sustain board are hot.
The 2 larger heat sinks on the y-sustain board are cold, while the smaller one near the bottom is hot.

From what it seems, the entire y-sustain board is bad. Are there any other steps I should take to diag the problem? TIA.

[tom66]

Re: Samsung Plasma TV - Worth Repairing?

Can you post a picture of the suspect capacitor?

Your symptoms do not match the typical bad sustain problem.

[tripps09]

Re: Samsung Plasma TV - Worth Repairing?

Here is a picture of the capacitor. It is right next to the power cable pin for the y-sustain.



Side view showing the profile:

[tom66]

Re: Samsung Plasma TV - Worth Repairing?

What are the values on that cap?

[tripps09]

Re: Samsung Plasma TV - Worth Repairing?

25V. 680 uF

[start2011]

Re: Samsung Plasma TV - Worth Repairing?

Here is a picture of the capacitor. It is right next to the power cable pin for the y-sustain.



Side view showing the profile:

Change that cap (680UF @ 25V) and picofuse , it should be 1A. also check resister next to red capaciptor.

[tripps09]

Re: Samsung Plasma TV - Worth Repairing?

I changed the capacitor last night, and nothing changed as far as the video went. The blue capacitor in the picture has a negative sign on one side, while my replacement cap had a giant 0 on the side. I'm guessing the side with the 0 on it is the negative side?

I'll try replacing that picofuse tonight, as well as testing the resistor. What values should I be reading on my multimeter?

Also, is there a way to test the cap to make sure I installed it properly and that it has a good connection with the solder?

[zukdj]

Re: Samsung Plasma TV - Worth Repairing?

Hey, any update on the 50" Samsung HPT5064? I have the same issue, sound but no video and I'd like to fix it. What is the best test? I see a green light on the Y board, if I remove the fuse the light goes off. Are parts in the Philips 50PFP5332D/37 interchangeable? I have one of those I could use for parts. I'd really like to get this TV working for my basement.