General Y-SUS / Y-BUFFER question

[PowerAmpFreak]

Hello!
I've got a general question about Y-SUS and Y-BUFFER in plasma sets.
IF, the bottom half of the screen is all OK, and the upper half of the screen is having problems with the picture, it's kind of fuzzy. THEN, the Y-SUS drive board should be all ok? The Y-SUS doesn't contain separate circuitry for bottom and top half of the screen, right?
So, this problem is most likely caused by a bad Y-BUFFER, right?
It's a Samsung PS-42S5H from 2005.

[hoadle]

Re: General Y-SUS / Y-BUFFER question

Here some general about Y-SUS and Y-BUFFER in plasma sets

Diagnosing Plasma TV Problems

By: Dachary Carey

If your plasma TV problems are interrupting your regular viewing, it's time to dig up your user manual. Many people pride themselves on not opening a user manual, but if you're having plasma TV problems, the user manual is the perfect place to start diagnosing your issue. Most manufacturers list common issues in their user manuals, along with easy fixes. If you can't find your specific problem in the plasma TV manual, contact your manufacturer for help. In the event of a known issue, technicians can help you diagnose the problem over the phone and suggest appropriate courses of action. People often spend countless hours trying to avoid consulting the user manual or calling the manufacturer, when a few minutes with either of these options can help diagnose or even fix common plasma TV problems.
Some of the problems below happen with many plasma TV sets, so check if any of these problems apply to you:
My plasma TV has no picture, and lines along the top or bottom.
When you run into lines appearing along the top or bottom of your plasma screen, and the television won't display a picture, it's typically because the y-sustain board or the z-sustain board have failed. In the event of a y-sus or z-sus failure, technicians replace both boards simultaneously because there's no test to determine whether the y-sus or z-sus has failed.
My plasma TV just won't turn on.
If your plasma TV won't turn on, check to make sure all of the plugs are securely seated. Try plugging your plasma TV into a different power source just to see if it powers up in a different outlet. If your plasma TV still doesn't turn on when you try plugging it into different outlets, you could be looking at an internal power supply problem or failure of another part. Plasma TVs contain self-diagnostic programs that turn the TV off if it encounters a problem that could cause a critical failure.
In either event, you'll need to have a technician run tests on your TV set. If it's a power supply issue, and you have a reasonable degree of technical competence, you can order a replacement board online and perform the work yourself. If it's a deeper plasma TV problem, a technician may have to perform the repair, or it might just be time to replace your plasma TV.
Fixing a plasma TV problem with red, green or blue pixels.
Occasionally, some of the plasma TV pixels get "stuck" in a single color position, either red, green or blue. Many home users who aren't afraid to tinker with their electronics fix these "stuck" pixels by adjusting the voltage on the plasma screen's vscan setting. To adjust the voltage, you must remove the back panel of your plasma screen and look for a controller for vscan, typically designed for adjustment with a Philips screwdriver. Adjust this setting until the "stuck" pixels function normally. Beware of over-adjusting, as you can cause long-term issues with your screen.

No Picture On Your Plasma Tv Set
Ok lets start ever wonder why your plasma tv set has no picture or why one night you were watching your tv set and then come in the morning to turn it on with no picture but sound.Well my friend i am here to tell you that this is a common problem with plasma tv sets, it is not the brand of the tv set or who build the tv set it is just bound to happen with time. The sad part about it is that some of the manufacturers know this but the name of the game is to make money, cant be mad with that i would like to make a little bit more money other than my fulltime job, but hey thats another subject.Moreover what can be causing this problem or why does this happen.Instead of boring you with a long article i am going to get right to the point and what is it that you can do yourself to fix it yourself.Ok this problem is coming from your Y sustain board which works with the Z sustain board to create the picture, it works just like the old tv sets with the vertical and horizontal deflection circuits.The reason that this happens is very simple after to much hours of usage by you the circuit board is like anything else (like us getting old) gets old and some of the components are not functioning like they are supposed to most of the time it is the fet transistors in that circuit that go bad and have to be replaced.Another problem that can cause this would be the tv set being programmed to a specific hour usage, this just means in simple english that if your tv set was programmed to be used for lets just say 40,000 hours before something goes bad or faulty, then that is just the way the people builded that tv set, less likely but it does happen.By this time you are probably asking yourself what can i do about this problem to fix it myself, well the first thing is to be very careful when doing it yourself, second is to aquire the service manual for your tv set from either fixya.com or eserviceinfo.com, third is to contact the manufacturer of the tv set and get the repair kit that they have for your tv set which consist of the Y sustain board the Zsustain board and the X sustain board or logic board.Once you have all this now you can do it yourself by following the instructrions on the service manual, remember to be careful and have the tv set unplugged from the wall before you service it, you should be able to change out the boards by yourself.Change the boards out and your tv set should be up and working normal again,have fun while you are doing it but be safe and save money on the repair cost.Hope this article helps whoever needs help and Thank You very much for reading.

[PowerAmpFreak]

Re: General Y-SUS / Y-BUFFER question

No hard feelings, but there is nothing covered regarding my concerns above in this very basic troubleshooting manual. There is no news in this for me actually.
I have specific questions, waiting for an answer.

[PlainBill]

Re: General Y-SUS / Y-BUFFER question

Hello!
I've got a general question about Y-SUS and Y-BUFFER in plasma sets.
IF, the bottom half of the screen is all OK, and the upper half of the screen is having problems with the picture, it's kind of fuzzy. THEN, the Y-SUS drive board should be all ok? The Y-SUS doesn't contain separate circuitry for bottom and top half of the screen, right?
So, this problem is most likely caused by a bad Y-BUFFER, right?
It's a Samsung PS-42S5H from 2005.

Yes, it's most likely caused by a bad buffer. I'd seriously recommend replacing both Y buffers; this appears to be one with the buffer board problem.

PlainBill

[PowerAmpFreak]

Re: General Y-SUS / Y-BUFFER question

Thanks, Bill for your reply.
As I thought, there are no separate power circuitry for upper and lower half of the screen, except for the two Y-BUFFER boards.
If one of the halfs are bad, the problem must be in the respective buffer board.

[PowerAmpFreak]

Re: General Y-SUS / Y-BUFFER question

As you already mentioned, Bill. There are many lines in the upper half of the screen, which is bad, also most of the y-buffer heatsinks are really hot. The lower y-buffer also has a few bad lines, and two hot buffer heatsinks. This means both buffer boards are in need of replacement.
Is this model known for bad y-buffers? (PS-42S5H)

[PlainBill]

Re: General Y-SUS / Y-BUFFER question

As you already mentioned, Bill. There are many lines in the upper half of the screen, which is bad, also most of the y-buffer heatsinks are really hot. The lower y-buffer also has a few bad lines, and two hot buffer heatsinks. This means both buffer boards are in need of replacement.
Is this model known for bad y-buffers? (PS-42S5H)

The problems occurred on a certain model of Samsung plasma panel, I don't have the panel number close to hand. Another way is to look at the Y-Sustain and / or the buffers. The following Y-Sustain and Y buffers are known to suffer from failures after about 5 years. The theory is the silicone sealant covering the leads of the buffers breaks down, an arc forms, destroying the buffer chip and the Y-sustain.

Y-Sustain PCB LJ92-01200A / PBA LJ41-02759A

Upper Y buffer PCB LJ92-01202A / PBA LJ41-02760A

Lower Y buffer PCB LJ92-01203A / PBA LJ41-02761A

PlainBill

[retiredcaps]

Re: General Y-SUS / Y-BUFFER question

The theory is the silicone sealant covering the leads of the buffers breaks down, an arc forms, destroying the buffer chip and the Y-sustain.

Full details at Coppell

http://blog.coppelltvrepair.com/2010...according.html

[PowerAmpFreak]

Re: General Y-SUS / Y-BUFFER question

Full details at Coppell

http://blog.coppelltvrepair.com/2010...according.html

Thanks for that link, very interesting. I was prepared to replace both buffers, but as the Y-SUS board was obviously operating, I didn't believe this was in need of replacement aswell.
Then, in that case this repair is going to be way too costly (as you earlier mentioned, Bill. Right as always).
So how on earth could an obviously operating Y-SUS board take out two new buffer boards?

[PowerAmpFreak]

Re: General Y-SUS / Y-BUFFER question

While we're on the subject of silicone isolated driver chips on Y-buffer boards, there seems many different boards use some kind of silicone applied to the legs of the driver chips. Is this a bigger problem than we think? If the isolating silicone colapses, arcing may result between the legs of chips and cause permanent damage to the y-buffers and sustain board IPM/Mosfet bank.
Or do we believe the colapsing silicone problem is more or less "isolated" to the Samsung Y-buffers P/N:
Upper Y buffer PCB LJ92-01202A / PBA LJ41-02760A

Lower Y buffer PCB LJ92-01203A / PBA LJ41-02761A

[PlainBill]

Re: General Y-SUS / Y-BUFFER question

While we're on the subject of silicone isolated driver chips on Y-buffer boards, there seems many different boards use some kind of silicone applied to the legs of the driver chips. Is this a bigger problem than we think? If the isolating silicone colapses, arcing may result between the legs of chips and cause permanent damage to the y-buffers and sustain board IPM/Mosfet bank.
Or do we believe the colapsing silicone problem is more or less "isolated" to the Samsung Y-buffers P/N:
Upper Y buffer PCB LJ92-01202A / PBA LJ41-02760A

Lower Y buffer PCB LJ92-01203A / PBA LJ41-02761A

That pair seems to be a very common failure point. Right now there are a couple of TVs on the local Craigslist with the problem buffers. The same buffer ICs were used by other manufacturers; they were on the buffers of the LG plasma sets I worked on a year ago. I would GUESS that there were problems either with the particular grade of silicone used, the factory had used the correct grade, but it came from a bad batch, or there was a problem with prepping the boards before applying the silicone.

PlainBill

[cadiman]

Re: General Y-SUS / Y-BUFFER question

I haven`t replaced buffer boards on any tvs that had heat sinked buffers...yet.
This must help to some extent. The upper buffer board always seems to be hotter and those are the ones that I replace the most.