Horizontal lines on a Philips 50pf9830a plasma

[Spork Schivago]

Hi,

This is the first plasma I've ever worked on. A customer brought it and there's rainbow coloured horizontal lines going across the screen. I can take pictures if you want to see what that looks like.

I lay it down flat and tear it open. Then I realize it's a plasma and remembered when we bought our plasma, they said not to lay it down flat. From Google, it says the reason not to lay them flat is because the screens inside way a lot and the extra pressure can break them. How do you guys normally work on them? Just be extra careful and lay them down horizontal?

I notice a bad capacitor and think easy fix. There's three boards that look like power supply boards. One is in the middle of the TV, and then there's one each to the left and right. This bad cap was on the to the left (if you're looking at it from where you plug the power in). I replace it. It's a 680uF 25v. I use a 680uF 35v because that's all I had. I turn it back on, hoping the problem would be fixed, but nope. Still has the horizontal lines.

I notice a voltage regulator that looked a little burned next to the cap. I thought maybe that's bad.

The voltage regulator says

ka78
05r

I believe it's a Fairchild voltage regulator. I found a datasheet, but I'm not 100% sure it's the right one. https://cdn.badcaps-static.com/pdfs/...692974ad9c.pdf


According to that PDF though, the fat tab is a ground. If I use that as a ground and put the red probe on the output, my multimeter jumps around as if nothing's hooked up at all. But if I measure the input pin to the middle ground, I get 10V (it bounces a bit), and for output, around 3.5V ~ 3.7V (it bounces a bit). If I measure the fat tab in reference to the middle pin (ground), I get around 9mV. I'm thinking the voltage regulator is testing good.

Anyone with experience with plasmas ever have symptoms like this and have any ideas where I should start?

There's also a few green LEDs on what I'd call the logic board. One of those is blinking green.

I can send pictures of the boards, but there are a lot of boards. So, right now, I'll just upload a picture of the entire TV with the back off and maybe if you guys want pictures, you can just tell me which board, and I'll send nicer pics of that.

The picture with the red box around the capacitor is the capacitor I replaced. Above it, you can see the voltage regulator.

Thanks!

[tvtimmy]

Re: Horizontal lines on a Philips 50pf9830a plasma

Horizontal lines scream bad upper buffer board to me. Dont run it until you replace it, it could take out the ysus board.

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

I'm going to try reseating the cables on what I think are called the buffer boards and see if that helps. But from what I've read, a bad IC or a cable needing reseating on the buffer boards will cause black horizontal lines, not multicoloured or rainbow coloured horizontal lines.

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

Horizontal lines scream bad upper buffer board to me. Dont run it until you replace it, it could take out the ysus board.

tvtimmy,

We were cross posting. But don't bad buffer boards cause black horizontal lines? How can I verify which buffer board is bad?

I'd also like to add that this customer got the TV for free, on the side of the road, years ago, and paid a place 300$ to fix it. It looks like they replaced some capacitors on a board near what I think are the buffer boards. This is a lot different type of tv than what I'm used to working on, so please bear with me if I don't get all the names of the boards right.

Thanks!

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

I believe the bad capacitor I replaced was on what's called the YSUS board. Is there a chance there's more than just a bad cap that was bad on that YSUS board that might be affecting the buffer board to cause the multicoloured lines?

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

If I'm understanding this correctly, I think there's a total of 6 buffer boards, and an upper y scan drive and a lower y scan drive, plus the y-main board. I reseated the cables on the y scan drive boards, because they were easy to get to. Is the y-main board also called the YSUS or Y Sustain board? That y-main is the one that had the bad cap.

Maybe I should remove the metal that hides the lower buffer boards so I can see if there's any bad caps hiding there....

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

Here's some pictures of the TV turned on for a very brief amount of time. This is after I reseated those cables that I could reseat (not on the upper and lower buffer boards, but the one hooked to the YSUS board that's off to the left if standing behind the TV).

[tvtimmy]

Re: Horizontal lines on a Philips 50pf9830a plasma

That looks like a zsus board problem, the one on the left hand side. Possible panel failure?
Take it out and check for cold/bad/cracked solder joints. I would touch everything up with fresh lead solder too be safe. Hamie or reecey will chime in and give better advice.

[ReeceyBurger123]

Re: Horizontal lines on a Philips 50pf9830a plasma

That aint a buffer fault, Xsus seems to be dead IMO. Ipm is probably shot.

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

That looks like a zsus board problem, the one on the left hand side. Possible panel failure?
Take it out and check for cold/bad/cracked solder joints. I would touch everything up with fresh lead solder too be safe. Hamie or reecey will chime in and give better advice.

The zsus is the board that had the bad capacitor? I thought that was called a Y-Main or a Y-SUS or a Y-Sustain board.

I want to make sure I got the terminology right here. The three boards at the top of the TV are buffer boards. The three boards at the bottom are buffer boards. With the TV laying on the floor and the back cover removed, looking down at the TV, all the way to the left is the Y-Main / Y-SUS board and attached to that are the Upper Y Scan Drive and the Lower Y Scan Drive. To the far right, I believe that board is called the X-Main Board or the X-SUS or the X-Sustain board. In the middle of the TV I believe is a power supply board. Then there's the logic board(s). Does that sound about right?

I haven't heard of the Z-SUS board yet. Not sure which one that is.

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

That aint a buffer fault, Xsus seems to be dead IMO. Ipm is probably shot.

What's an Ipm? I've searched google and can't find much on them. Came across a badcaps post about a person replacing one, but that's it. Also, where's the X-Sus board? I've uploaded a picture with labels to what I think are the Y-SUS and X-SUS boards. The red box is what I've been calling the Y-SUS, the one that had the bad cap. The blue box is what I think is called the X-SUS. Not sure where the Z-Sus board that tvtimmy mentions is. This is the first plasma I've taken apart.

Is there any way to test the X-SUS? I wish I could verify the IPM is bad before ordering a new board.

Here's a link to a video of a person removing the IPM. Still not sure what one is or what it's purpose is, but I'll keep looking.

https://www.youtube.com/watch?v=byN2UJTni3o

Are we certain there's not more wrong with the board that had the blown capacitor? The one I call the Y-SUS? No way something else bad in on that board, maybe that voltage regulator, could cause something like this?

Thanks for all the help guys. These plasmas really are different beasts altogether, aren't they?

[rccrasher65]

Re: Horizontal lines on a Philips 50pf9830a plasma

The zsus is the board that had the bad capacitor? I thought that was called a Y-Main or a Y-SUS or a Y-Sustain board.

I want to make sure I got the terminology right here. The three boards at the top of the TV are buffer boards. The three boards at the bottom are buffer boards. With the TV laying on the floor and the back cover removed, looking down at the TV, all the way to the left is the Y-Main / Y-SUS board and attached to that are the Upper Y Scan Drive and the Lower Y Scan Drive. To the far right, I believe that board is called the X-Main Board or the X-SUS or the X-Sustain board. In the middle of the TV I believe is a power supply board. Then there's the logic board(s). Does that sound about right?

I haven't heard of the Z-SUS board yet. Not sure which one that is.

x-main, x-sus, z-sus all the same board located on far right side.

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

x-main, x-sus, z-sus all the same board located on far right side.

Thank you. I gotcha. I've been reading a good deal about Plasmas, trying to get a better understanding of how they work. I believe the Y-SUS is responsible for the lines on the Y-Axis (vertical lines) and the X-SUS is responsible for the lines on the X-Axis (horizontal lines). Why do they sometime refer to it as a Z-SUS though? Was the information I reading incorrect on why they're called what they're called?

Replacing the bad cap on the Y-SUS made no difference as far as we can tell. I thought that was a bit odd.

Anyway, I couldn't find a new X-SUS on ShopJimmy. I couldn't find a new one on e-bay. But I did find a used one on e-bay for 14$, free shipping. I ordered that. I'm hoping that fixes the problem.

There was another problem too. The digital tuner doesn't work, only the analog tuner works. This TV supports digital TV, so hooking one of those antennas made for digital TV should have brought in some channels. Around here, we get 7 or 8, without an antenna. I'm thinking that might be something on the logic board though and will start checking tomorrow, while I wait for the X-SUS board to come in the mail.

Thanks!

[ReeceyBurger123]

Re: Horizontal lines on a Philips 50pf9830a plasma

Order the Xsus see if it fixes it, to test it use bcn and google to find how to test Ve voltage and sus output voltages from the Xsus.

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

Order the Xsus see if it fixes it, to test it use bcn and google to find how to test Ve voltage and sus output voltages from the Xsus.

What's bcn? Do you mean Badcaps.net? Maybe I should have tested the Ve voltage and sus output voltages from the Xsus before ordering the replacement Xsus.

Was I right about the functions of the X-Sus and Y-Sus boards? If I am, I'm curious as to why there weren't any vertical lines with the bad cap that was on the Y-SUS board....from what we can tell, replacing that bad capacitor on the Y-SUS didn't make any difference at all, unless it had something to do with the digital tuner, which I highly doubt....

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

Quick question here. With a normal LCD or LED television, the voltage and amperage is high enough to give me a nasty shock if I do something wrong, but from what I've read, with Plasmas, it might be high enough to actually kill me. So I'm trying to be extra safe.

Anyway, with a normal TV, I might keep some of the ribbon cables unhooked from the T-CON board for testing purposes. With boards like the X-SUS, there's three ribbon cables that go to (I'm assuming) the panel. Is it okay to power up the TV with those ribbon cables unplugged, for testing purposes? Or would that be a really bad idea?

Thanks!

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

Okay, I got some measurements.

THe X-SUS Vs signals (there's two), reading from the power supply board with the DMM on auto-range, just bounces all over, meaning there's no voltage going there. The Y-SUS board though shows 194.7VDC on both Vs signals.

If I'm reading the sticker right, that Vs should read 200VDC. The sticker is a table though and it's a little confusing to read. I believe I have to adjust the Vs potentiometer. There's potentiometers for Ve, Vs, Va, VScan, VSet, and 12V. I have connections on the X-SUS and Y-SUS (not all connections are on both connectors) for Vs, Ve, VScan, VSet, D5V. I haven't checked the other voltages yet though.

I was watching a youtube video on how to test the various boards. The guy says you can unhook the Y-SUS connector from the PSU, turn on the TV, see if the problem goes away, if not, hook it back up, then do the same for the X-SUS. When we unhook the X-SUS, the problem is still the same. When we unhook the Y-SUS, there's no picture at all.

Should I adjust the voltages now or wait until the used X-SUS board gets here?

Also, there's a blinking LED on the logic board. There's also a steady LED on the logic board. One's blinking, one isn't.

[ReeceyBurger123]

Re: Horizontal lines on a Philips 50pf9830a plasma

Anything electrical can kill you, just dont touch things while its on unless yours sure it isnt passing a voltage Ie grounded heatsinks. Also test Ve should be 98v or so. Ive been shocked by a ccfl inveter before (my fault being careless-1000v) that made my shoulder hurt for a while I tell yoy.

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

Here's a picture of the voltage sticker.

If I'm reading it correctly, Va should be 70VDC. 5V2 (can't find a potentiometer to adjust that) should be 5.2VDC, Vsc (or VScan) should be -175VDC. 5Vsw (don't know what that is yet, can't find a pot) should be 5.2VDC. Vs should be 200VDC. 8V6 should be 8.6VDC (can't find a pot), Ve should be 90VDC. 12V should be 12VDC. VSet should be 195VDC. Vsc_H should be -55VDC (can't find a pot, I believe this is scan high bias (Created by the DC-DC power block of the Y Drive board)). Snd_P should be 18.0VDC (can't find a pot, I think it's sound positive), Snd_N should be -18.0VDC.

[Spork Schivago]

Re: Horizontal lines on a Philips 50pf9830a plasma

Anything electrical can kill you, just dont touch things while its on unless yours sure it isnt passing a voltage Ie grounded heatsinks. Also test Ve should be 98v or so. Ive been shocked by a ccfl inveter before (my fault being careless-1000v) that made my shoulder hurt for a while I tell yoy.

Am I reading the sticker wrong? Should Ve be 98VDC or should it be 90VDC? Also, what's the Vg pins for? I'm going to test all the pins for the X-SUS and Y-SUS, the ones that the sticker lists at least.