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Old 06-08-2022, 07:33 PM   #1
TheDuDe06
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Default Seiki SE42UMT, Standby Light, No power On

Hi, I have a Seiki SE42UMT that don't power on anymore.

The standby red LED will stay lit but nothing else.
I can hear a constant high pitched sound from the power supply board.

I already have replaced the power supply but the problem still persist so, we can rule out that the power supply board is good.

I also inspected visually every boards and I can't see anything that could have burnt or blown capacitors.

Here are attached few pictures of the 3 boards.

Thank you !
Attached Images
File Type: jpg 20220608_214729.jpg (1.09 MB, 25 views)
File Type: jpg 20220608_214740.jpg (1.12 MB, 15 views)
File Type: jpg 20220608_214807.jpg (1.83 MB, 12 views)
File Type: jpg 20220608_214835.jpg (1.89 MB, 15 views)
File Type: jpg 20220608_214849.jpg (1.97 MB, 7 views)
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Old 06-26-2022, 06:41 PM   #2
TheDuDe06
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Default Re: Seiki SE42UMT, Standby Light, No power On

Nobody have a hint where I need to look ?

If I need to give more infos or more tests let me know !

Thanks !
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Old 06-26-2022, 06:59 PM   #3
neilc6
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Default Re: Seiki SE42UMT, Standby Light, No power On

If you have standby light and standby voltage and the TV doesn't turn on, the main board is suspect. Could be eeprom but don't see it in your pics. If you can find the eeprom, you can try freezing it within upside down can of duster before plugging in.

Squealing can be caused by shorted caps on the main board. See if it stops when you unplug it and measure for shorts on the supply rails on the main.

Last edited by neilc6; 06-26-2022 at 07:16 PM..
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Old 06-26-2022, 07:08 PM   #4
dskall
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Default Re: Seiki SE42UMT, Standby Light, No power On

I would start unplugging things on the power board until high pitch sound stops and then narrow down which board is loading power supply.
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Old 06-26-2022, 07:33 PM   #5
TheDuDe06
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Default Re: Seiki SE42UMT, Standby Light, No power On

Thanks guys now I have something to work on. I'll let you know my results.
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Old 06-27-2022, 03:09 AM   #6
nomoresonys
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Default Re: Seiki SE42UMT, Standby Light, No power On

looks like the caps are not holding up, if I wanted to do the least, I would replace the what is it 4 1000 uf 25 volt caps, with 1000 uf 50 volt and see what happens, I suspect they were using cheap caps. hold up on the (I just got a new board) ALL the boards will be old, might not solve the problem but it's the simple place I would start at.

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Old 06-27-2022, 03:30 AM   #7
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Default Re: Seiki SE42UMT, Standby Light, No power On

and check all the solder joints, they are prolly old too.
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