Samsung PN50C540G3FXZA 50" Plasma, power cycling, Y-Main problem, Canada

[bcstedt]

Just starting to crack into this one and wanted to get the ball rolling.

At power on (plug in), power light on, relays click, repeat (sometimes)

After disconnecting Y-Main from SMPS power stays on and boot up jingle is heard from speakers

Removed Y-Main for inspection and testing

This pic from:
PN50C540G3FXZA Fast Track Troubleshooting Manual - Rev 1/10/12

[bcstedt]

Y-Main board

Model No: 50U(F)2P X-MAIN(1LAYER)
PCB No: LJ41-08457A
Rev No: R1.2(09/11/18)

[nomoresonys]

Test everything you can on y-main, be sure to check the transistors for shorts, a short will show continuity between any of the 3 pins of the transistor, so if you measure in ohm mode and have close to 000 ohms thats a short.

[bcstedt]

Components I'll be testing shortly from the Y-Main board.

Results are DCV from DMM diode test.

SMALL HEATSINK
Q6000 - SMK1360 MOSFET
/OL/OL/0.525//OL/OL/0.1+/

Q5402 - GT30F123 IGBT TOSHIBA
/0/0/0//0/0/0/ - (shorted)

Q5401 - GT30F123 IGBT TOSHIBA
/OL/OL/OL//OL/OL/OL/ - (open)

D5406 - RF1501 Diode 300V 12A
/0//0/ - (shorted)



LARGE HEATSINK
Q5102 - RJP63F3
/.017/.017/0// same / - (shorted)

D5101 - STTH12R06FP Diode 600V 12A
/0.371//OL/

Q5403 - GT30F123 IGBT TOSHIBA
/.017/.017/0// same / - (shorted)

Q5408 - GT30F123 IGBT TOSHIBA
/.027/.027/0// same / - (shorted)

D5402 - STTH1004FP
/0.422//OL/

Q5303 - 1K31AJ
/OL/OL/0.503//OL/OL/1.835/

Q5304 - RJP30E2
/.011/.011/0// same / - (shorted)



D5401 - RD2006 Diode 600V 20A
- 0.389/OL

[bcstedt]

Y-Main

Small Heatsink


Large Heatsink

[bcstedt]

With the Y-Main board disconnected, the SMPS test points read:

Vs = 212VDC (211 on label)
Va = 54.8VDC (55)

Not sure where to check Vsc & Ve yet.
(I need the Y-Main functioning to get these)

[nomoresonys]

Yep it's a mess, many just try to get a good replacement board from somewhere because of how hard parts are to find and all the counterfeit components that are being sold.

[bcstedt]

Yep it's a mess, many just try to get a good replacement board from somewhere because of how hard parts are to find and all the counterfeit components that are being sold.

Thanks, I'm beginning to see that. I've got a few other things to check before I order a board but I don't even know if the PDP is functional.

[nomoresonys]

Not a fan of plasmas, cons seem to outweigh the pros, too heavy, too hard to repair because of hard to find parts etc, use 3 times as much energy, 1080 max resolution, just to name a few.

[bcstedt]

I finished testing the Y-Buffer, X-Main and SMPS boards. All diodes and transistors check out but there is some soldering rework needed.

I've ordered an X-Main board and hope I'll find an acceptable result soon. Updates to follow.

[bcstedt]

Did some solder rework on the SMPS and X-Main boards. Inspect & test the "new" Y-Main board, looks good and significantly less heat damage.

Installed & test. Was getting some hissing noises from the Y-Buffer and the screen looks like this:

[nomoresonys]

Make sure y-buffer to y-main connections are as they should be. For testing unhook y-buffer from y-main, because a faulty buffer can kill a y-main and vice versa, maybe test the little mlc caps on y-buffer at least for shorts and retest y-buffer IC's , testing there if needed: https://www.youtube.com/watch?v=5hVi5gd0aec