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Shahid, Technician
Category: TV
Satisfied Customers: 10823
Experience:  I have been repairing electronic gear since 1993 as a qualified Sony tech
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Shahid! while ago I've got some tips on trobleshooting

Customer Question

Hello Shahid!
For a while ago I've got some tips on trobleshooting my Samsung LED TV. Model code UE55D7005LUXXE.
It's first now I'm trying again.
I did some measurements on my power board and I was able to measure constant 5 Volts in standby on the pin 18, but I'm still not sure about the main board. There should be a reason why it's rebooting. Can You help me to do somme measurements more so it becomes more clear to me? I would like to turn power supply on with main board disconnected so I can check about other voltages are as they have to be before purchasing main board.
Thank You!
Submitted: 1 year ago.
Category: TV
Expert:  Shahid replied 1 year ago.

Hello, my name is ***** ***** I'll assist you.

Looking at attached pictures and get back to you in few minutes.


Customer: replied 1 year ago.
To get it more clear I'm adding link to video from our last conversation.!BVEyiZqD
Expert:  Shahid replied 1 year ago.

Above link ask for decryption key :-)

Customer: replied 1 year ago.!BVEyiZqD!IRH9lOcx1glThLXIWCv1zuQ7apGhbQmV2z-GZwmmcb8
Try this
Expert:  Shahid replied 1 year ago.

OK, what volts appear at pin-20 (PS-ON) of connector CNM801 of power board that goes to main board?

Customer: replied 1 year ago.
It is swiching from 0.2 to 3.3V
Expert:  Shahid replied 1 year ago.

OK, please unplug connector of CNM801 and again check volts at pin-20.

Customer: replied 1 year ago.
Expert:  Shahid replied 1 year ago.

OK, to check the power supply board output volts please jump the pin-20 to GND pin (14 or 16) to turn On the power supply without connecting the main board. You should get B13V at pin-7,10 and B5V at pin-17, 19 etc.

If these volts are available then power board is working. Regarding turning On backlight section, it is bit complicated as it needs command and pulse width modulation signal (PWM) from main board to turn it On.

Please reply back with the result.


Customer: replied 1 year ago.
Do I have to use a resistor or it's ok to cut it short?
I'll do that a bit later and will replay.
Expert:  Shahid replied 1 year ago.

I would recommend to solder a piece of wire to jump the pin-20 to pin-14 or 16 then replug TV power cord in and check output volts of power supply board.


Customer: replied 1 year ago.
Hi Shahid!
I've been very busy at work. I haven't done measurements yet. All do then tomorrow and write back.
Expert:  Shahid replied 1 year ago.

Hi, no problem, please take you time.


Customer: replied 1 year ago.
For me it works a bit different.... I'm able to measure
Without jumper on pins 7 and 10 I have 12,9V; pins 17 and 19 is 5V.
With jumper relay is swiching off.
Expert:  Shahid replied 1 year ago.

OK, that means power supply board is working, jumping the PS-ON pin to ground turns Off the power supply which indicates all is set at power supply board and issue would be with main board in TV, replacement of main board will help to resolve the issue.

I trust my input will help you out. Please feel free to respond if you have any additional questions.
A positive rating to answer would be greatly appreciated, please click on 5 star on this page then click submit/finish button so I can get credit on website for my work.