Samsung Television will not power on

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Samsung Television

Repair guides and support for your Samsung TV.

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Gerald @myth9

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Samsung Television will not power on

Model Code: PN42C430A1DXZC

TV will not power on. There is no backlight or picture on the screen. There is a standby light on. When I attempt to power on the TV, there are clicks coming from what I think is a relay, the light goes off for about a second, then it is back on solid.

No visibly blown capacitors or burnt components on the power supply board.

The following are the voltages taken from CN801:

1) 3.31V

2) 5.27V

3-12) 0V

When i hit the power button #1 drops to .05V, the clicks are heard then back to 3.31V

#11 goes to 15.10V, clicks then back to 0V

#12 goes to 5.24V, clicks then back to 0V

T-con board fuse:

@oldturkey03

Voltage reference for LED driver boards:

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Just to add. I thought based on those readings that it could be a power supply board, but the replacement board is doing the same thing.

Gerald 의 2019년 7월 29일

@oldturkey03 yes, I tried the mainboard and still the same 2 clicks and then.. nothing.

Gerald 의 2019년 8월 2일

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Gerald @myth9

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SOLVED: Hope this helps someone with a similar issue:

I managed to source all replacement parts for this TV . I started to replace parts individually. It wasn't until the LED driver boards were replaced that a picture came up. As @oldturkey03 mentioned above, better equipment(ie. Oscilloscope) would've helped to determine for sure that they were the issue.

Unlucky me got to find out that the screen was cracked though. Couldn't tell by the initial visual inspection that it was there.

@oldturkey03 thanks again for assisting.

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Just to add. I thought based on those readings that it could be a power supply board, but the replacement board is doing the same thing. — Gerald
@oldturkey03 yes, I tried the mainboard and still the same 2 clicks and then.. nothing. — Gerald

oldturkey03 @oldturkey03 평판: 782.3k 1.1k 893 2.3k · Answer 1 · 2019-07-30T04:49:23-07:00

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oldturkey03 @oldturkey03

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@myth9 based on the voltages coming from your power board it appears as it is your main board that is not turning the TV on. Remember that it is the main board that tell the power board to turn on. Disconnect the mail board from the power board and try to turn it on. See if you now have the backlight on. Check the T-con board for power as well. You should get 12V on the fuse of the t-con board. Let us know what you find.

Okay your voltages are off and not having power to the T-con board would normally make me replace the power board. Something is definitely off. You have a new main board and a new power board but still have the same issue. In that case the only thing you really have left is the T-con board. That would be an odd error for that but anything is possible. you are certain your replacement main and power board are good boards? You checked all your cables etc., all looks good?

You also did not tell us the complete voltages from CN801.

Pin 4

Pin 7

Pin 8

Pin 10

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@oldturkey03 After disconnecting the mainboard from the power board, the backlight does not come on. When I initially plug the TV in and the clicks are heard, there is a small green LED that flickers on/off on the T-con board. The fuse marked (F2000) on the T-con board has continuity but does not show a 12V reading when plugged in.

For the heck of it, I unplugged the T-con board from the power board and only 1 click is heard from the relay and I hear the sound the TV makes when it turns on but still no picture or backlight.

Gerald 의 2019년 8월 1일

@oldturkey03 OK. The following are the readings I got with ONLY the mainboard and power supply board connected. The TV stays on long enough for me to get these:

CN801 - ONLY MAINBOARD

1 - 0.06v

2 - 5.23V

3 - 0V

4 - 14.92V

5:6 - 0V

7- 5.27V

8 - 5.26

9 - 0V

10 - 14.92V

11 - 14.92V

12 - 5.26V

Which are good readings I think. The power turns on, the music plays and the TV clicks back off after about 10-15secs.

When the T-con board is added to the mix, so just the power supply board, mainboard and T-con board. Again, the TV plays the music as if it's turning on, same readings for CN801. Still no voltage reading across the T-con board's fuse. CN802 gives the following readings:

1 - 5.26

2 - 5.26

3 - 0V

4 - 0V

5 - 0.06

6 - 0V

When I connect what I think are the inverter boards, the initial problem occurs. 2 clicks from the relay and then nothing.

The mainboard and power supply boards were apparently removed from TV's that had broken displays. I don't see any damage on the cables, they all look good.

Gerald 의 2019년 8월 3일

Check those LED driver boards and see if the connectors on there show any kind of voltage reference.

oldturkey03 의 2019년 8월 3일

@oldturkey03 When I disconnect power from the T-con board, meaning mainboard as well as inverter boards are connected to the power supply board, again music plays but nothing on the display. Here are the readings from the inverter board.

CN5000

1:2 - 0V

3 - 14.92V

4:5 - 0V

CN5004

1 to 3 - 0V

4 - .09V

5 to 11- 0V

12 - 14.92V

13 - 0.11V

Gerald 의 2019년 8월 3일

Okay so now you get sound but no picture? Change the T-con board