Samsung PN50B650S1F clicks on plug-in with flashing voltages

[DXseekerMO]

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

Where to from here?

[DXseekerMO]

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

Bump

[DXseekerMO]

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

Hello can I get some help please? Thanks

[DXseekerMO]

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

Hello? Have we run out of road here? Help please!!!!

[freakaftr8]

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

So Right now you have confirmed that shorting the control board test patterns do not do anything are you still getting the constant clicking from the power supply? I noticed that your VS and VA come up and drop off. Under that assumption I would say that your power supply is OK.

Assuming you have nothing lighting up on the screen at all, Disconnecting both upper and lower buffer off the y main Try powering it up then. This will alleviate a loaded down buffer shutting down the power supply and a restart pattern

[DXseekerMO]

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

Ok great! Thanks for jumping back in! With the ribbon cable unplugged from the logic board and pins 3 and 4 shorted the clicking/cycling still happens. The screen never tries to light.

Earlier I tried disconnecting the power supply and lower ribbon cables from both x and y main boards and the unit still cycles. Is this the test you wanted me to do?

[freakaftr8]

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

Which ribbon are you referring to? Are you for referring to the ribbon that goes from the logic board to the y main? In that case if so you could leave the ribbon cable unplugged and leave the power connector connected to the Y main.

See if the power cycling stops

[freakaftr8]

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

I wanted you originally to remove the scan boards or the buffer boards. These are the boards with the square ICs on the very left side that connect to the Y main. All you have to do is remove the screws in pop the connection from the y

[DXseekerMO]

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

OK gotcha. Unplug Y-buf from Y-main. Do I need to unhook the ribbon cables from the plasma screen before I pull the screws and detach the buffer board, or is there enough clearance?

I think I see where this is heading, detach buffer board(s) plug it in and see if it stops cycling?

FYI I detached the cable from the SMPS to both buffer boards and it still power cycled.

Thanks for your patience. I'm a noob!

[freakaftr8]

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

Ok. There are no direct power connections between the power supply and the buffer boards. The buffer boards are the scan boards that are connected directly to the panel on the left side sustain board.

the sustain boards have the power connection from the switch mode power supply.

What I want you to do is disconnect those buffer boards and every connection that connects the sustain board to a buffer board. You can leave the buffer board hanging on the ribbons that go to the panels to speak careful when you disconnect the board get a flat head screw driver and gently pop the board away from the sustain

[freakaftr8]

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

But if you do not want to do this you can simply unplug the flat white ribbon cable that connects the logic board to the y sustain board and leave everything else connected. This will in turn to disable data drive from the logic board.

Sometimes switch mode power supplies need to have some kind of load in order to keep the voltages up

[DXseekerMO]

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

Okay so I went ahead and unplugged the ribbon cable from the logic to y-sus. Unit still cycles. For entertainment value I also unplugged the ribbon to the x-side from the logic and it still cycles.

I'm starting to get this terminology down. Thanks for your patience.

[DXseekerMO]

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

Okay so while I'm asking for help I'm also trying to self-help.

I found this video: https://www.youtube.com/watch?v=VtbrQhwBiOc in which the person is testing the exact same SMPS I have. I followed this procedure as outlined in the video:

The board was connected to 120V AC, like in the video. All other connectors were unplugged.

Ps ON and STBY voltages are present and correct.

Jump Ps ON to ground: all voltages noted on the SMPS to main board connector are present and correct.

Jump STBY to Vs: All voltages are present and correct at Vs and Va, Vg is 15.1V DC but when voltage is read at the capacitor leg noted in the picture, voltage is only 340V DC, as compared to the 396V DC seen in the video.

Does anyone think this voltage difference may be a part of the problem?

[slap_happy]

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

Your set has ps board #BN44-00274A. Shopjimmy has a repair kit for that board which contains the following parts:

Part Number: BN44-00274A Repair Kit
Kit Includes
Description - Quantity - Board Location
Integrated Circuits - 2- ICB801S, ICP801
Resistors - 2 -RB807, RP807
Transistors - 4 - QP802, 803, QS801, 802
Diodes - 3 - DB804, 814, DP802
Fuses - 1 - F801S, FB801S

They depend on their kits fixing most problems, so even if you have no interest in their kit, check the above part locations.

Maybe also watch this video (below) which shows troubleshooting of the somewhat similar #BN44-00445A, including power factor correction testing:

https://www.youtube.com/watch?v=dswtNRiZwN8

[DXseekerMO]

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

I saw that kit on the SJ website and checked some of those components in-circuit. Still have some to look at tho. Are you thinking the SMPS may need repair?

I'm off to watch that video! Thanks

[slap_happy]

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

I don't know. Most of your recent test values seem okay except for the 340V.

[DXseekerMO]

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

Agreed. Watched the video. Thanks for posting that.....very informative! He even said 390V was about the correct voltage at that point.

[freakaftr8]

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

I'm not too sure but you should be getting proper output voltages sense you can see those proper voltages at sustain boards when the power supply comes up before the restart.

On your Connector going to the main board you will have a pin for PS_ON. Can you monitor this pin and see if voltage goes to 5v with an drops off when power supplly restarts?

Even though you watch the video yes you can ground PS on and you can also ground VS on. This should make the power supply come live and not re start.

And if it does come on with no restarts I would say that your main board is faulty.

[DXseekerMO]

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

Okay I just did that. Here's what I see:

The instant the plug makes contact with the prongs PS_ON voltage of 3.28V DC appears. When I hear the first click click PS_ON volts drop to 0.16V DC and return to 3.28 after the second click click, lather rinse repeat.

With the SMPS unhooked from everything but AC volts (wall) and PS_ON grounded the unit remains powered up and does not cycle. Same with VS_ON to STBY, no cycling.

[freakaftr8]

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

Power supply is good. Do an ohms test on both sustain boards. You will be checking the vs pin to ground on each board. Do this with those both disconnected from power supply.