Will not power on correctly, black screen

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75” Samsung Q60 QLED TV qn75q60rafxza

75” Samsung Q60 QLED TV.

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AJCNFL @ajcnfl

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发帖于: 2023年6月7日

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Will not power on correctly, black screen

SAMSUNG QN75Q60RAFXZA

Black screen, hearing a click noise about every 15 seconds, power light is on. Not responding to remote. Will not turn off (click noise about every 15 seconds from P/S) have to unplug to power off.

Other symptoms: Sometimes when you turn off TV it would come back on after 30 seconds. Before the TV went black, things started to act weird. Had to go in and clear memory and running apps. Then started to get a malicious process pop up notifications.

Took back cover off and used multimeter.

Power Supply BN44-00874E connector CNM802 to the Main Board BN94-14119C. Disconnected this cable, Have backlights now and the click noise stopped.

Checking the connector (CNM802) from P/S, Pins 3-9 had correct 13V, Pin 2 ANA Dim 3.35V, Pin 4 On/OFF 0V, Pin 6 PWM BLU 2.8V, Pin 8 PWR ON 4.56V. (Disconnected from main board)

Connected the cable back, clicking started and checked connector again. Pins 3-9 still 13V, Pin 2 now 0 to .24V, Pin 4 still 0V, Pin 6 now 0.04 to 0V, Pin 8 now 3.53V but changes to .11V when it clicks.

Leaning toward a bad main board, but have not checked the transistors or diodes on the P/S. Does anyone know what I should be reading for an ohms measurement on the transistors? The fuse on P/S was good.

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cisom99 @cisom99 声誉积分: 13 2 · Answer 1 · 2023-06-08T13:09:02-07:00

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cisom99 @cisom99

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Circled in red

Yes.. just ran across this post today.. I decided take it apart to see if it was a simple before throwing it away...The clicking that AJCNFL was speaking of, is the relay switch in the picture.. I have removed both ribbons for the left and right side of the screen, one at a time. And the TV stayed on with sound but no picture.. So I'm guessing it would be the LCD panel....I was going to try the tape method but not time for it.

Power board

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@cisom post some good pictures of both sides of your power board. this could be a mainboard issue or an issue with the relay not getting the power properly. Check the connections for any odd looking solder pads.

由 oldturkey03 完成的 2023年6月8日

@cisom99 excellent. The large format Samsung's have lots of issues with the panel driver boards. Tape off could be a work around. Did you have issues like this "Not responding to remote. Will not turn off (click noise about every 15 seconds from P/S) have to unplug to power off." as well?

由 oldturkey03 完成的 2023年6月8日

@cisom99 can you do the same quality picture for the component (front) side?

由 oldturkey03 完成的 2023年6月8日

Yes..but for some reason I'm having trouble uploading..

由 cisom99 完成的 2023年6月8日

@cisom99 you can only post pictures it answers or question not as comments

go to edit this answer and see if you can insert it just like you would when you post images into an existing question 在已经存在的问题里加入图片

由 oldturkey03 完成的 2023年6月8日

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oldturkey03 @oldturkey03 声誉积分: 784.9千 1.1千 894 2.3千 · Answer 2 · 2023-06-07T14:58:17-07:00

oldturkey03 @oldturkey03

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@ajcnfl you are not telling us if the clicking comes from the power board or from the main board. The values you are giving are pretty much what is expected. This could be a bad relay on the power board or a bad main board. REmember it is the mainboard that tells the power board to turn on etc. Post some pictures of your boards with your Question. That way we can see what you see.

在已经存在的问题里加入图片

@ajcnfl "Disconnected this cable" I assume you are referring to the one from the main board.All of this"before the TV went black, things started to act weird. Had to go in and clear memory and running apps" sound like a bad main board.

This

Power Supply BN44-00874E connector CNM802 to the Main Board BN94-14119C. Disconnected this cable, Have backlights now and the click noise stopped.

is correct behavior from the power board

This

Connected the cable back, clicking started and checked connector again. Pins 3-9 still 13V, Pin 2 now 0 to .24V, Pin 4 still 0V, Pin 6 now 0.04 to 0V, Pin 8 now 3.53V but changes to .11V when it clicks.

is what I would expect from a faulty main board.BUT check the solder connection of the relay. Something not right about this "3.53V but changes to .11V when it clicks."

"Does anyone know what I should be reading for an ohms measurement on the transistors" you'll need to measure all of those individually to their specs.

Post another picture of the power supply as large and clear as you can. the original you post is to small to enlarge and to check it. We need to see both sides of the board.

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Edited post, and added pics. Hopefully there will be some answers. Wish I had schematics. If it is Power Supply I would be able to fix, but the main board is a different story. Thank you for your help.

由 AJCNFL 完成的 2023年6月8日

Its coming from the power board ( relay).

Mine is doing the same thing..

由 cisom99 完成的 2023年6月8日

Main board fixed my problem

由 AJCNFL 完成的 2023年6月24日

@ajcnfl like we suspected

由 oldturkey03 完成的 2023年6月24日

Thanks.... will try replacing it...

由 cisom99 完成的 2023年6月24日

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