Samsung PN60F5350 - Power Supply Board?

[overdrive1012]

So I stumbled upon a TV on Facebook Classifieds for parts and picked up this TV for $30. The seller claims that the tech that came out to his house said it only needed a power supply board. Before I went and ordered one, I wanted to see whether it was truly the power supply board or something else, since there is not power and no indicator LED's.

The first thing I did was test continuity on the in-line fuse and it is still good. Without testing anything else yet I did a visual inspection and noted a few things that look like they could be causes.

The circuits marked J831 and J852 appeared to be shorted by melted solder as shown in the pic. In addition, the area to the right of those circuits on the thermistors appears slightly darkened, as if overheated, but I haven't tested the thermistors yet.

Also, the solder on the capacitor marked as CX818 on the board looks like it may have overheated and may need to be resoldered.

[R_J]

Re: Samsung PN60F5350 - Power Supply Board?

Check if you have stby voltage on pin2 of Cn801 I think it should be around 5vdc, If it is there, check pin 1 and see if changes when the power button is pressed.

J831 and J852 are just jumper wires connecting two traces, as for the discoloration around the thermistors, that is normal, they run warm and heat the board.
Check the voltage across either of the two large caps, CP801 or CP802, it should be 160vdc in standby, closer to 400v when pfc is working.
The standby ic is the one mounted to the heasink with all the silicone around it, check its solder connections.

[overdrive1012]

Re: Samsung PN60F5350 - Power Supply Board?

I got 4.2V from the standby pins. The large caps each read 170V. Looking at the heat sink there is what looks like 3 MOSFETS that are surrounded in silicon. Is one of those the standby IC’s?

[R_J]

Re: Samsung PN60F5350 - Power Supply Board?

The standby ic. is the one next to the small blue cap CB804. Do you have PS-ON voltage on pin 1 of CN801 ? measure the pin then press the power button, does the voltage change?
Are you sure the tv is not trying to turn on? With the boards in the Tv and connected, check the VS-TP on the power board, there should be around 200vdc (check the sticker on the panel for the VS voltage)

[overdrive1012]

Re: Samsung PN60F5350 - Power Supply Board?

Forgive my ignorance but how do I probe the pin while the connector is attached to measure the change?

[R_J]

Re: Samsung PN60F5350 - Power Supply Board?

Pin 1 connects to J875 (jumper wire) right next to CN801

[overdrive1012]

Re: Samsung PN60F5350 - Power Supply Board?

There was no change in the pin 1 reading when the power button is pressed. Stayed at about 2.4v. I also did not get a reading from VS-TP (the post above the VS-ADJ).

[R_J]

Re: Samsung PN60F5350 - Power Supply Board?

I see shopjimmy offers an eeprom for the mainboard, that could be the problem.
If you unplug the cable going to the main board, what voltage do you get on CN801 pin #1, 15 & 17

[overdrive1012]

Re: Samsung PN60F5350 - Power Supply Board?

4.2V on pin 1. Nothing on 15 or 17

[R_J]

Re: Samsung PN60F5350 - Power Supply Board?

It looks like pin 1 needs to be taken to ground to turn on the power supply, if you take that pin1 to ground, do you get any voltage on pin 15 or 17? do with out main connected

[overdrive1012]

Re: Samsung PN60F5350 - Power Supply Board?

Does it have to stay grounded or only grounded momentarily?

[overdrive1012]

Re: Samsung PN60F5350 - Power Supply Board?

I did some digging on google and found a few threads where the main board dies and shows these symptoms. Would the eprom be enough or are there other components to consider?

[R_J]

Re: Samsung PN60F5350 - Power Supply Board?

The pin one needs to stay ground to turn on the power supply, If 15 and 17 come up to 5 volts, they would need to then be grounded to turn on the Vs, If those pins stay low they likely need to be connected to stanby 5v via a 1k resistor to turn on Vs.
Its a good chance though that it is the main board

Another thing to try is to freeze the eeprom either with cold spray or an inverted caned air.
with all board connected, unplug the tv, freeze the eeprom ic, plug in the tv and try turning it on. If this works the eeprom is bad, if it does'nt work the eeprom could still be bad.
Usually if the replacement eeprom fixes the problem, thats all it will need.
If you do order an eeprom, make sure you get the correct one for your main board

[overdrive1012]

Re: Samsung PN60F5350 - Power Supply Board?

Which one is the eeprom?

[R_J]

Re: Samsung PN60F5350 - Power Supply Board?

Ic801

[overdrive1012]

Re: Samsung PN60F5350 - Power Supply Board?

Is it more economical to buy the eeprom for $20 (with shipping) or the whole board for $42 (also with shipping)?

[R_J]

Re: Samsung PN60F5350 - Power Supply Board?

I think I would go with the board, if it happens not to be the board, you can at least resell it.

[Andrew F. Ali]

Re: Samsung PN60F5350 - Power Supply Board?

I think I would go with the board, if it happens not to be the board, you can at least resell it.

+10

[overdrive1012]

Re: Samsung PN60F5350 - Power Supply Board?

No dice using the freeze spray. Time to order the board..

[overdrive1012]

Re: Samsung PN60F5350 - Power Supply Board?

I know it’s been a few months but I finally got around to ordering a replacement main board and swapped out the existing board. TV is as good as new now! $30 for the tv, $75 for the main board. Not bad for a 60 inch plasma!