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50" Samsung HP T5054 no picture (lex ky)

post #1 of 10
6/25/10 at 5:42am
Thread Starter 
I bought a 50" Samsung HPT5054 for 100.00 yesterday. The audio on the tv sounds fine but there is no picture coming through. The lady I bought the tv off of said this all started after a thunder storm passed through. They were watching tv at the time, but after this they could never get a picture. I've read online that there might be a problem with the x and y buffer boards. I've also read that it is a simple fix by replacing some of the capacitors.

Ive taken the back cover of the tv off. I don't see any problems they mentioned as far as the capacitors leaking or the caps bubbling up. The more I read the more I find several Samsungs have this problem.

Is anyone here familiar with with this issue on Samsungs? Or would anyone here possibly know a reputable repair place in central Kentucky?
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post #2 of 10
6/25/10 at 7:18am
I would let a proffesional look at this. On Plasma sets with noi pic but ok audio there are multiple problems to choose from. What you have stated about the X and Y sustain boards can hold true. But you could have a bad Y buffer board, or your Panel could have taken 1 or more of the boards. If you feel up to the challenge I will give you some trouble shooting tips.

1. Looking at the Panel with a flashlight. Look at the grid very thouroughly and look for a black spot like something popped. If you see that then stop there, your Panel is bad.

2. With the set unplugged, disconnect the top Y Buffer board. Located on the far left side looking into the back of the set. Plug in the set and turn it on. If you see half of your display then replace that board. If not then go to step 3.

3. unplug the set. Reconnect the top Y buffer and disconnect the lowwer Y Buffer. Plug the set in and turn it on. If you see half of the diplay, then replace that board. If not then reconnect.

After all of this andd you have no pic, then probably will be your Y sustain board, but there is no gaurentee. Good luck to you
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post #3 of 10
6/25/10 at 1:55pm
Thread Starter 
thanks for the advice! I will check this tonight when I get home from work.
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post #4 of 10
6/25/10 at 5:11pm
Thread Starter 
I spent about 15 minutes doing step one. I didn't see anything. I didn't know how big of spot to look for but the panel is clean. Tried steps 1 and 2 to no avail. Looked at how much the y sustain board was on this tv and nearly cried at $180.00. That's too much for me to buy and that not be the problem. So it looks like I have to call the pros and tell them What I know it's not and buy their sustain board at a marked up price and then their labor. Thanks for the help though
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post #5 of 10
2/17/11 at 6:25pm
Hello all,

New to the forum but wanted to add a very basic trouble shooting tip for the Sound but no picture problem on the Samsung HPT5054 Plasma 50".

There are two ceramic fuses on two separate boards when you open this sucker up. All the boards that control the picture/screen are on the left side as you look at the back of the set. You'll notice two narrow boards along the left edge of the case...These are the Y buffer boards. They are one over the other and have ribbon cables that curl around to the screen. Those two are connected to a larger square board...the Y Sustain board. On this board is a white ceramic fuse...this will be on the upper right side of said board. The wires that power the board come into the same location.

Check the continuity of this fuse. Its impossible to tell if its blown unless you 1. check it or 2. have no picture.
This should be your first step after making sure the set is plugged in.

I mention this because I just bought this set for $145...the guy had replaced a power supply and cables. I spent $4 and change on a bag of fuses and now have a perfectly functioning 50" plasma.

NOTE: Use a ceramic fuse to replace the original ceramic fuse. Glass ones will not take the heat this set generates and will become a problem. My Radio shack didn't carry these in the size needed, so you may have to go online to find them.

I'll try and get pics up of the boards and fuse location.
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post #6 of 10
1/26/12 at 9:55pm
I apologize in advance for bumping this thread back from the grave, but I couldn't find my answer so a search brought this thread up.

I have the aforementioned problem with this TV, and these are the troubleshooting steps that I have done so far:

1. tested the fuse on the Y-sustain board with a multimeter (set it to the triangle with a line function and got a reading of 009, fuse is good)
2. unplugged top y buffer board(unplugged the 3 ribbon cables on the side), turned TV on and no video but audio
3. plugged in top, unplugged bottom y buffer board, turned on TV, same result.

I did notice that when the TV was on, a couple pixels in the top half of the screen would flicker various colors for a couple of seconds (only ~8 pixels did this) and then stop.


I have checked over all of the boards and have found no black spots or bad capacitors.

Can someone help me with the next steps? TIA
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post #7 of 10
1/26/12 at 10:05pm
I think I found my answer:

Quote:


Originally Posted by eecho789
Thought Id put this in here for people looking to repair a sound but no picture issue and for a future placeholder. I have no idea if this has been touched on before so forgive me if it has.

90% of the time it's a y buffer that goes out. It's usually the top buffer. 3/4 or more of the time the buffer takes out the y main board too.

You cannot just replace the y-main or buffer because it will just burn out the other within seconds if one is bad.

Also about 1/4 of the time it'll take out the top transformer on the power supply too.

The solution?
First disconnect the power to the y main board. turn on the television and check the voltages coming off of it. Careful it's high voltage 208V! Remember it's DC too.
Then disconnect the buffers from the y main board. You can try powering the y-main up to see if the little LED lights up. This does not indicate it's working though but it'll tell you if it is possible to fix.
The fixes for these boards is only for electronics guys. It usually involves replacing 1-3 capacitors and 1-4 FET's. Since a bad buffer can take out a good y main in seconds it's usually recommended that one replace all 3 boards at the same time.
It's a $250 fix.

How do I know all this? I've now repaired 5 of these televisions. I owned one and spent close to 600 repairing it. I bought misc parts and broken sets online for months before I had 2 different repair guys walk me through the process of repairing them.

I had so much cash tied up in parts that I bought 3 more dead sets and repaired them to justify all my spending.

I've never had an x board fail. I've had EVERY top buffer fail. I've had all but 1 y-mains fail. And only 1 lower buffer fail. I've also had the y buffer fry it's top chip, blow a capacitor and FET on the y-main, and fry the top transformer on the power supply before my eyes.
It only took 5 seconds and had a loud bang.

Replacement of the 3 y boards will almost always fix the sound but no picture problem. Cost for all 3? $250.

Avoid used. If one board is bad it could burn out any good parts you have. Thats why the 3 boards come in kits.

Check out New Zeland and England where these sets are much more common. Hope this helps!
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post #8 of 10
1/26/12 at 10:35pm
IS this capacitor most likely my issue? It's on the Y-sustain board right below the fuse:

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post #9 of 10
4/3/12 at 2:11pm
Sorry to reopen a thread but this is close to my isssue and a good thread it should be stickied!
I had my set fixed in Nov 2012 under warrenty. They replaced the Y buffer upper and lower then Y sustain and finally power supply which fixed the set. Now 4 mo. later my warrenty is out and the set will randomly drop video but the sound stays on. I can get to OSD menus. If I turn it off and back on the picture returns. This is on all inputs etc...since the picture does return after resetting the TV I am not sure weather this thread would help or not. I dont want to have to wait till it blows all three before I fix it.
Thanks for any help!
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post #10 of 10
1/25/13 at 5:55pm
I currently have this set torn apart with the same problem. The TV was given to me and has sound, powers up and no picture. has a very hot electrical smell. Found the MOSFET chip under the edge of the smaller heat sink on the "Y" board has fried. Melted damn near though the PCB. If you dont look real close you wont see it, if you pull the board you definitely will see it as this one scorched the metal backing plate of the screen. I havent found any other components that seem to have gone bad. This TV was in a home that was experiencing some weird power surges and the TV wasnt on a surge protector.

The offending chip is again a MOSFET (transistor) part #
B20NK50Z
GK120 VW
CHN 739

My question is can I use this MOSFET to replace it. Honestly, if it works great, if not, I really dont care as it was free.

http://www.ebay.com/itm/STB20NK50Z-Manu-ST-Encapsulation-TO-263-N-CHANNEL-500V-0-23-OHM-17A-/120920855362?_trksid=p3284.m263&_trkparms=algo%3DSI%26its%3DI%26itu%3DUCI%252BRTU%252BUA%252BFICS%26otn%3D21%26pmod%3D120922013632%26ps%3D54

Thanks!
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