Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

[AFajitas]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

Got it. Thanks for being so patient with me.

here are my measurements:

1. used as a ground while reading all the pins
2-4. 0v
5-10. 5.97v
11-12. 0v
13-14. 12.17v
15-18. 0v
19-22. 5.49v
23-26. 0v
27-30. 13.27v
31-32. 0v

Also noticed after a few minutes, TV will click off and one of the two LED's near the header I am measuring turns off. I then have to unplug the TV, plug it back in and use the power button to turn it on. If I unplug the power before it clicks off, the next time I plug it in, it will click on by itself without me pressing the power button.

Still giving me 5 blinks from the power button LED.

[Agent24]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

Interesting, it looks like all the rails from the PSU are there. Funny that there seems to be no PS_ON signal present through...

What voltages do you get on the other connector, CN801?

Do any voltages on either connector change after the LED on the mainboard goes out?

Which LED goes out? I found a schematic, perhaps something will be indicated if we can find out what the LED is for.. unfortunately the rest of the manual is missing... (http://elektrotanya.com/samsung_lns4.../download.html)

Another thing you could do, is measure the outputs of all voltage regulators on the mainboard and check they are all OK.

[AFajitas]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

Interesting, it looks like all the rails from the PSU are there. Funny that there seems to be no PS_ON signal present through...

What voltages do you get on the other connector, CN801?

Do any voltages on either connector change after the LED on the mainboard goes out?

Which LED goes out? I found a schematic, perhaps something will be indicated if we can find out what the LED is for.. unfortunately the rest of the manual is missing... (http://elektrotanya.com/samsung_lns4.../download.html)

Another thing you could do, is measure the outputs of all voltage regulators on the mainboard and check they are all OK.

Interesting, it looks like all the rails from the PSU are there. Funny that there seems to be no PS_ON signal present through...

What voltages do you get on the other connector, CN801?

Do any voltages on either connector change after the LED on the mainboard goes out?

Which LED goes out? I found a schematic, perhaps something will be indicated if we can find out what the LED is for.. unfortunately the rest of the manual is missing... (http://elektrotanya.com/samsung_lns4.../download.html)

Another thing you could do, is measure the outputs of all voltage regulators on the mainboard and check they are all OK.

Ok, apologies, my probe must not have penetrated pin2 properly. Getting 4.231v from it. I tested all the other pins again to make sure I didnt miss anything. Going to test the voltages after the TV clicks off and CN801.

LED that goes out is labeled OP182

[Agent24]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

It sounds like the PSU is probably OK, if it's getting the PS_ON signal and all the rails are coming up.

But I think the PS_ON signal should only be sent when you press the power button, so it seems as if the mainboard may be at fault. If you have a faulty button it may cause some problem like this, but I am not sure.

All I can think at the moment is check all the onboard regulators on mainboard and see if any are outputting an incorrect voltage or not working... if a rail is missing it can indicate faulty regulator or shorted parts on that rail, causing the regulator to shutdown.

I wonder if that melted casing has anything to do with a shorted and overheating part?

Budm can probably give you more advice than I can at this point...

[budm]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

If you are sure that you do have PS_ON signal, then you need to find out if you also have >360VDC RIGHT AT THE TWO LEGS OF THE MAIN FILTER CAP (the big 450VDC cap in the primary side).
You will have to get to the two legs of the caps which will be very dangerous because it is in the HOT DEADLY SIDE OF THE CIRCUIT, you should plug the TV into the GFCI outlet at least.

[AFajitas]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

May have to install a GFCI outlet before going any further. I'm thinking about buying a new mainboard on ebay to see if that is truly the problem, I can always resell it if it is not. That type of shotgun diagnosis is probably sacrilegious around here, huh?

[Agent24]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

Did you ever try with the TCON disconnected? I think you said earlier the melted part of the case was closest to that board. If the TCON is bad but everything else is OK, disconnecting it should restore functionality with the exception that all you'll see is a blank white screen.

There's nothing wrong with replacing the whole board, of course pinpointing the exact part and replacing only that part is the ultimate thing in repair, but at the end of the day, if it works and the price is right...

I would say at this stage it is probably unwise to order a new mainboard just yet before trying to get some more evidence for which board is bad at least.

[AFajitas]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

Did you ever try with the TCON disconnected? I think you said earlier the melted part of the case was closest to that board. If the TCON is bad but everything else is OK, disconnecting it should restore functionality with the exception that all you'll see is a blank white screen.

There's nothing wrong with replacing the whole board, of course pinpointing the exact part and replacing only that part is the ultimate thing in repair, but at the end of the day, if it works and the price is right...

I would say at this stage it is probably unwise to order a new mainboard just yet before trying to get some more evidence for which board is bad at least.

I did try removing the t-con board to no avail.

Well, I hate to say this but I should have removed the main board first and looked underneath of it. It appears that many areas underneath the main board or cooked. Please see attached pictures

[CapLeaker]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

That is flux... clean it off with alcohol, acetone etc and a brush. That board is not "cooked".

[AFajitas]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

Thanks. Was hard and "crispy" and scrapes off with my nail, still learning. Can you see the IC chip that has white marks on it in the pictures? Is that a problem?

[budm]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

So what DC Voltage do you have on the main filter cap with PS_ON present?

[AFajitas]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

I don't have a GFI outlet available to me right now; am I safe to measure the filter cap very carefully as long as I am on a grounded outlet? Also, I need guidance on testing it.. I am assuming it's the largest capacitor on the power supply? How do I test it if I am unable to get to the leads?

[budm]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

You will have to solder two long wires to the two legs of the cap and then attach the wires to your DCV meter to take the reading.

[AFajitas]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

You will have to solder two long wires to the two legs of the cap and then attach the wires to your DCV meter to take the reading.

Done. When I plug in the TV the voltage just jumps around from .01 to .05 volts and when it's unplugged I'm getting a small erratic reading as well. Does this mean my capacitor is bad?

[budm]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

That cannot be right, did you hear the power relay RL811S click on?
Can I see the good clear pictures of the bottom side of the board?

[Agent24]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

Probably you are not measuring it correctly. If the main filter capacitor was genuinely at 0.05 volts then the thing would be dead as a doornail, and it does at least try to power up.

The capacitor voltage should be something about at least 350 volts, DC.

Make sure your meter is on DC Volts, not AC, or some other range. Make sure you are on a range that can display what is expected - so the 500v, 750v, or 1000v (DC) range is what you need.

Did you solder wires to the right capacitor?

[budm]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

That cannot be, you must make an error in readings. The filter cap is the main filter cap which used for the standby power supply and the main power supply, since the standby power supply is working then that reading cannot be 0V.

[AFajitas]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

My solder joints were bad. 388 volts is what Im reading. It's a 450v 220mf capacitor.

[budm]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

Good, how about good clear pictures of the bottom side of the board?

[AFajitas]

Re: Samsung LN-S4095D - Won't turn on; Power LED 5 blinks - I think I see a problem

Good, how about good clear pictures of the bottom side of the board?

Here ya go.