PN58A550 Plasma TV 'Logic Main Board' Test

How to isolate and test the Logic Main Board on a Samsung PN58A550 Plasma TV.

Use this procedure at your own risk! Make sure power is off while jumpering stuff and sticking your hands in the back. There are many high voltages.

Time Index 0:00 Startup Fail #1
Time Index 0:50 Startup Fail #2
Time Index 1:30 Test Procedure

My Samsung PN58A550S1FXZA Plasma TV started acting up a few weeks ago. The screen would scramble when I first turned it on, but then it would power-cycle self-reboot and the picture would be OK after that (after a warmup?). I was guessing something in the Power Supply because it has over-current and Over-voltage monitoring circuits and I though one of those was causing the reset.

After measuring and checking some of the SMPS voltages, the power supply board seemed ok, so I started looking elsewhere. I found a test mode on the Logic Main Board. By shorting 2 pins of a 4-pin header, you can cause the board to generate some video test patterns. Effectively this removes the Main Control and Input board, and tests the whole rest of the TV.

The pins you jumper on the Logic Main board are pins 3 & 4 of the 4-pin header CN2013. The pins are labeled 3 & 4.

To turn on the power supply without the Main control board connected, you jumper pins 1 & 5 ON THE SMPS CONNECTOR CN801. Pin 5 grounds Pin 1, which enables the supply. The pin numbers are different at the Main Board end of the Cable. Pins 1,3,5,... become Pins 2,4,6... for some reason. 2x12 connectors are numbered 1,3,5,...,9,11 on the top row (look for the triangle marking pin 1) and 2,4,...,10,12 on the bottom row.
This procedure will work on other Samsung TV's but connector locations and boards may be slightly different.

Good Luck!

I believe I have isolated the problem to a 10uF tantalum and/or the 5V to 3.3V buck regulator on the Main board. The Cap is C102(10uf,10v) and the IC is IC101 (MP2363DN). These parts are on the back of the Main PCB. If I applied a little heat to those 2 parts before I power the unit on, it starts up fine. Shop Jimmy has a repair kit that contains these 2 parts, but it cheaper to order them at Mouser.com.
https://www.shopjimmy.com/samsung-bn9...

Here is the Repair Video    • PN58A550 Main Board 3.3V Power Suppy Repair  

PN58A550S1FXZA
PN58A550
PN50A550

Logic Main Board
LJ41-04802A
PCB LJ92-01457A
PBA BN96-05645A

Main Board
Model Pearl
BN41-00975C(2008.07.31)
BN97-02039B
BN94-01660B

SMPS PSPF701801A BN44-00183A (Switched Mode Power Supply)
Here is a link to the schematic of the SMPS board.
https://elektrotanya.com/samsung_bn44...
I took the pdf to FedEx Kinko's and printed the file on 11x17 paper and it was very readable.