Samsung PN50B650S1F clicks on plug-in with flashing voltages

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Is that with the buffer boards detached?

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Okay I ohms tested the Vs on both x and y sustain boards. There are two Vs pins on each. Both Vs pins on the x and ysus read a very high level of resistance then go open.

[freakaftr8]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Good. Go ahead and reconnect both boards to the power supply. Then power up with PS on grounded only. Does power supply stay on?

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Disconnect ribbon cable from main board? or just jumper with it hooked up?

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

I unplugged the ribbon cable for the main board, jumpered PS_ON to ground and the unit DID NOT power cycle! LED 2000 flashes once per second.

Main board?

[freakaftr8]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Try the same procedure with VS grounded as well. If power supply still comes live check your VS voltage and VA voltage. If all looks well then yes main board is at fault..

And yes all these procedures are with the cable disconnected from the mainboard. So yes you are doing it correctly

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Ok I grounded Vs/STBY along with Ps/ground. Power supply remains live, Vs and Va voltage correct!

Buddy, you walked me through that like Sherman went to the sea! Well done and thanks a whole lot for being so patient with an amateur, and the appreciation goes for everyone who stepped up and helped!

Looks like all the reliable sources for main boards are all sold out right now. Are there any repair options available?

Again...well done and thank you!

[freakaftr8]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

No problem man that's what we're here for! You could try heating up the main board with a hair dryer especially around the processor in see if the TV comes up. Could be something as simple as a bad soldering job underneath the main processor.

Could you post a clear picture of the front and back of the main board?

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Interesting you should ask that. I just pulled the board and look what I found on the back of it.....

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

And the front....

[freakaftr8]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

That dried creamy looking shit is normal believe it or not. I see a lot of Samsung boards like that. Should have no bearing or effect on the way it's acting. Those components underneath the main processor look rather toasted. I wouldn't be surprised to find out the main processor has some ball grid array bad contacts underneath.

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

This?

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Bad soldering job on the processor.....ball grid array.....is this why one might "re-ball" a processor?

I have a heat gun....and nothing to lose.....so could I pull the heat sink off the processor, hit it with the heat gun on low and re-flow the balls out underneath?

If so I would need suggestions on how to get the heat sink/double sided tape? off without causing damage and pretty specific instructions on heating the chip up for the re-flow. If you or anyone knows of any video resources I tend to learn best this way.

[freakaftr8]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

You could start by this hitting the area with the heat gun with the heat sync still on. Focus around processor and rectangular ram modules. Also heat up and V ram this is the rectangular module with the pins coming off the side there's probably about 25 pins on each side.

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

How long should I heat it for, and how far away should I keep the heat gun from the chip/heat sink/components? Should I put something flat under it so the board doesn't sag?

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

I'm pretty sure that heat sink is going to have to come off. Can you tell me how to do that and put it back on? Simple as new tape and stick it on there?

[freakaftr8]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

It's taped on just apply a little heat in gradually pull away. However you could try just heating the hell out of the board and powering it up and see if the cycling stops.

Try heating up the NV ram module this is the rectangular one with the pins coming out the sides only smokes

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

My mistake. It actually looks like a paste or glue of some sort holding it on. It's gray in color, kinda metallic looking and has a slight amount of flex to it, very slight. Should I heat it, remove the heat sink then remove the remaining glue?

I'd bake this thing in the oven if I didn't think my food would taste like solder for a year!

[slap_happy]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Check the two coils near the power connector on the main board for 3.3v.

Something like (but also quite different from) done in this video:

https://www.youtube.com/watch?v=Wawf68FPv9A
or: https://www.youtube.com/watch?v=OuijG2RvfJ4

There are other common main board problems that cause flashing led on '09 era samsung plasmas (when the power supply is good), but I've forgotten them. I think one of them involves the sound ic or some other small ic.

The main cpu could be toast or have bga problems, but often with those you get flakey pic or int performance.

BN94-02855 main boards are running pretty expensive on ebay right now. When looking for boards this old I examine the pics closely and read the story about the board to try to determine how many hours are on the board.

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

OK so I borrowed a toaster oven from a friend and baked the main board at 400dgrs for 20 minutes. By the time it was done It was the tenderest main board I've ever had! lol?

Re-installed it in to the tv and still a no-go.

So for now and until I find another TV for parts or a cheap main board I'll be setting this thing aside. If I make any head way on it or have any other news I'll update later. Thanks for helping me find the problem everyone and have a good one!