Samsung PN60F5500, making me question my sanity

[Truncatedhose]

Re: Samsung PN60F5500, making me question my sanity

Okay, so there is no glow from the screen, but what do you mean by the LVDS cable? Do plasmas even have and LVDS? I thought only LCD/LED use these. f you're talking about a cable from the main board, which cable are you talking about specifically?

Also, to mtnickel, this TV doesn't have a separate logic board.

[rccrasher65]

Re: Samsung PN60F5500, making me question my sanity

Yes plasma's have an LVDS, go back to post 16 Tom66 explains all you need to do with a Samsung plasma Tv, click on the link he left, it will show you step by step what to do.

[Hamie]

Re: Samsung PN60F5500, making me question my sanity

This model doesn't have an lvds cable.

[mmartell]

Re: Samsung PN60F5500, making me question my sanity

Signal remains at board level with presumably much shorter travel distance so LVDS is not necessary. Even if it is it's integrated to the board circuit itself.

[vinceroger69]

Re: Samsung PN60F5500, making me question my sanity

maybe time to try a replacement mainboard? have you swopped any other boards?

[Truncatedhose]

Re: Samsung PN60F5500, making me question my sanity

Thanks for all the support, guys.

Hamie, there is no glow; checked in a dark room. I will try the BGA pressure once I confirm things below.

rccrasher65, what do you mean by the LVDS cable? I wasn't aware plasmas had one? Can you indicate what cable you mean specifically?

mtnickel, this model doesn't have a separate logic board. I could pull the X and Y again and check for shorted fets, but wouldn't there be a blown fuse if that was the case?

[Hamie]

Re: Samsung PN60F5500, making me question my sanity

OK so this is the control board section of the mainboard.

[Hamie]

Re: Samsung PN60F5500, making me question my sanity

This looks like the LED for the control board.

Does it blink? Either with the power supply jumpers in place or if you remove jumpers and plug back in mainboard?

If this led doesn't blink I'd seriously consider replacing the mainboard.

[rccrasher65]

Re: Samsung PN60F5500, making me question my sanity

Thanks for all the support, guys.

Hamie, there is no glow; checked in a dark room. I will try the BGA pressure once I confirm things below.

rccrasher65, what do you mean by the LVDS cable? I wasn't aware plasmas had one? Can you indicate what cable you mean specifically?

mtnickel, this model doesn't have a separate logic board. I could pull the X and Y again and check for shorted fets, but wouldn't there be a blown fuse if that was the case?

As Hamie stated your model does not have an LVDS cable. That was my fault for not reading entire thread. +1 for looking for new main board.

[Truncatedhose]

Re: Samsung PN60F5500, making me question my sanity

This looks like the LED for the control board.

Does it blink? Either with the power supply jumpers in place or if you remove jumpers and plug back in mainboard?

If this led doesn't blink I'd seriously consider replacing the mainboard.

It doesn't blink with the power supply cable unplugged and jumped the way you suggested and the jumper on pins 3 and 4 of the main board, but when I take that jumper off the main board and unjump and plug the power supply cable back in, then it has a slow blink. Also, I noticed that when I plugged in AC with those jumpers in and the power supply cable jumped, I no longer had any audio as I did with things plugged in normally. Perhaps something is not working when I try the unplug and jump?

[mtnickel]

Re: Samsung PN60F5500, making me question my sanity

By "a slow Blink", do you mean once every 5-6 seconds?
Mine did this too. It's an indicator of a fault. Some i think have said Drv reset.

Also, on the pn51f8500 I've been testing, to get the test images, the mainboard needs power. I know Hamie recommended to remove the power to the mainboard, not sure why. If that board doesn't get power, how will it fire up it's CPU and generate the test images?

But I wouldn't worry about generating test images since we know you know have a slow blink. I would first look to the X/Y main board since mine did exactly the same thing. You don't even have to pull it, just measure across all 3 terminals, 1-2, 2-3, 1-3. If you have a dead short on any of these pins on any fet, you likely have a problem. My replacement board for the pn51f6xxx was only like $16 shipped. check out how much a replacement is. May be worth it to try that next if it's cheap enough.

Regards,
Mark

[Hamie]

Re: Samsung PN60F5500, making me question my sanity

The control board generates the test patters not the mainboard.

On any other Samsung plasma with a separate control board you can generate test patterns without the mainboard. Usually the sustain board provide the power to the control board.

As previously pointed out I've never worked on this model. I'd be surprised If you couldnt run test patterns with jumpers inplace. But without a working model we my not know.

[Truncatedhose]

Re: Samsung PN60F5500, making me question my sanity

By "a slow Blink", do you mean once every 5-6 seconds?
Mine did this too. It's an indicator of a fault. Some i think have said Drv reset.

Also, on the pn51f8500 I've been testing, to get the test images, the mainboard needs power. I know Hamie recommended to remove the power to the mainboard, not sure why. If that board doesn't get power, how will it fire up it's CPU and generate the test images?

But I wouldn't worry about generating test images since we know you know have a slow blink. I would first look to the X/Y main board since mine did exactly the same thing. You don't even have to pull it, just measure across all 3 terminals, 1-2, 2-3, 1-3. If you have a dead short on any of these pins on any fet, you likely have a problem. My replacement board for the pn51f6xxx was only like $16 shipped. check out how much a replacement is. May be worth it to try that next if it's cheap enough.

Regards,
Mark

Thanks, Mark! By slow, I mean once every 1-2 seconds, haha, I guess my idea of slow is not as slow as yours!

I guess I will pull the X and Y and check all the fets and get back to you.

[mtnickel]

Re: Samsung PN60F5500, making me question my sanity

Blinking every 1 second indicates the mainboard status is ok. So an overload fault may be less likely.

[mtnickel]

Re: Samsung PN60F5500, making me question my sanity

The control board generates the test patters not the mainboard.

On any other Samsung plasma with a separate control board you can generate test patterns without the mainboard. Usually the sustain board provide the power to the control board.

As previously pointed out I've never worked on this model. I'd be surprised If you couldnt run test patterns with jumpers inplace. But without a working model we my not know.

On my newer samsung board (F series) board, the sustain board connected to the PS only has VS, VA, ground, and 15v. So in fact, the mainboard is actually supplying 5V to sustain boards (if it requires it), not vise-versa. So I maintain you probably need to power the Mainboard from the PS for that to work in this case.

On that samsung I've been playing with, I could only get a test pattern by jumpering the PS_on manually. This would turn the mainboard on to give a steady blinking LED. Without the jumper, the mainboard would just click on/off right away. Yours may not be that case as the unit failing to stay on is part of my problem. I left all other cable connections intact and displayed the test images just fine (with the 3/4 pin connected). I'm just trying to figure out why the unit won't stay on. In my case, I suspect a bad mainboard, but I already tried 1 replacement. Testing another next week.

[Truncatedhose]

Re: Samsung PN60F5500, making me question my sanity

Okay, so I tested all the components on heatsinks on the Y and X boards and the only shorted junctions I'm finding are on the X board: QS801C and QS802C read shorted (in both directions) only between the two pins adjacent to each other; they don't read shorted to the single pin by itself. This is in circuit; I haven't desoldered them. This an issue? Also, I had tried replacing this board, but it didn't solve the issue, but it's possible I got a bad board, I suppose.

[mtnickel]

Re: Samsung PN60F5500, making me question my sanity

Okay, so I tested all the components on heatsinks on the Y and X boards and the only shorted junctions I'm finding are on the X board: QS801C and QS802C read shorted (in both directions) only between the two pins adjacent to each other; they don't read shorted to the single pin by itself. This is in circuit; I haven't desoldered them. This an issue? Also, I had tried replacing this board, but it didn't solve the issue, but it's possible I got a bad board, I suppose.

Pictures?
Testing in circuit is usually ok. Is it a dead short (less than 1 ohm?). Also, I know on my board some parts looked like transistors but were just diodes. Could you read the number on their face?

[Truncatedhose]

Re: Samsung PN60F5500, making me question my sanity

Pictures?
Testing in circuit is usually ok. Is it a dead short (less than 1 ohm?). Also, I know on my board some parts looked like transistors but were just diodes. Could you read the number on their face?

I was testing in DIODE check, but when just checked with OHMS I found that both read 20.0 ohms either way between adjacent (side by side) pins. The number on both parts is: K15A50D. See picture attached. Thanks for your help!

[mtnickel]

Re: Samsung PN60F5500, making me question my sanity

20 ohms could possibly be normal. I'm no circuit expert, but on mine, the dead transistors were a dead short. One would likely have to look at the traces, see what it's driving, etc. Maybe others with more experience can chime in.

[mtnickel]

Re: Samsung PN60F5500, making me question my sanity

Did you try turning TV on with all cables connected properly and the 3/4 service pin jumpered? (instead of removing power to the mainboard).

If so, what was LED blink like?