Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

[Poab]

TV Model: Samsung UN60H6400AF

When I acquired this TV, it was already broken. I am now trying to repair it. Here are the facts.

1. When everything is connected properly, a red standby light illuminates. When I press the power button, the red light goes out momentarily then comes back on.

2. If I disconnect the t-con board, the red light still illuminates. When I press the bower button, the red light goes out momentarily then comes back on AND the backlight flashes once momentarily.

3. If I disconnect the power board from the main board, the backlight turns on, but the red standby light does not illuminate.

4. I have tried replacing the power board and the mainboard. This has not fixed the issue.

5. When I replaced the power board, nothing changed. When I replaced the main board, the standby light did not illuminate any more.

6. I checked all the capacitors on the power board by taking them out of the circuit and testing them with a multimeter. They all checked good. Additionally, the voltages coming out of the power board all checked good.

7. Lastly, I'm living in Japan right now. It seems unlikely, but could this have something to do with the slightly different electric grid (100V, 50 Hz)?

I've been working on this issue for 3 weekends now. It's been a fun project, but I think I'm at a point where I need some help from people who have more experience.

[Poab]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

Additional photos of the board.

Last photo was taken in a dark room with the power board disconnected from the main board. Interestingly, the red area in the middle of the screen was hard to see with the naked eye, but is in fact coming from the TV.

[CapLeaker]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

Unplug one side of the ribbon cables going from the tcon to the panel, check the screen, then do the other side.

[Poab]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

Unplug one side of the ribbon cables going from the tcon to the panel, check the screen, then do the other side.

No change. Unplugging one end or the other, when I press and hold the power button, the red stby light goes out for a moment, the screen backlight flashes, then the tv goes back to stby.

[Poab]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

I'm also curious as to whether or not the replacement mainboard may also be bad considering I don't see a standby light on when I install it.

[CapLeaker]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

O.k. So you got the backlights to turn on by unplugging the main board? The red dot shouldn't be there either.
On the PSU there is a ribbon cable that goes to the main board. Measure the DC voltages on each pin and post them with the corresponding pin out. This way we know what happens.

[Poab]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

O.k. So you got the backlights to turn on by unplugging the main board? The red dot shouldn't be there either.
On the PSU there is a ribbon cable that goes to the main board. Measure the DC voltages on each pin and post them with the corresponding pin out. This way we know what happens.

That's correct. The backlight does turn on.

1. PWM3: 3.27
2. PWM2: 3.27
3. Gnd
4. PWM1: 3.27
5. A13V: 12.8
6. 00_ON: 2.37
7. A13V: 12.8
8. 00_LE: 4.7
9. A13V: 12.8
10. BLU_ON: 2.24
11. A13V: 12.8
12. PS_ON: 4.5
13. A13V: 12.8
14. GND
15. GND
16. GND
17. NC
18. NC

[Nick's Tvs]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

If you are getting backlight with the main board disconnected then your power supply is more than likely ok. The board you received is more than likely bad if you no longer gets the standby light. Also that red dot could be refraction from your camera and I wouldn't worry about it. As for your actual issue you stated that the backlight flashes once and seems to go away. Samsung sets will flash very bright and then dim out on a no signal screen, so maybe it actually is not turning back off but is dimmed and seems off. Here are a few things you can do in order to figure out if you do have a bad main board:
1) Double check the voltage on the fuse located on the T-con board. Do you get 12 volts on each side?
2) Plug in a dvd player via HDMI and double click input on your remote. It will automatically detect something plugged in or go to the TV input. So you may have to do this twice, wait 20 seconds and do it again. We are doing this to listen out for sound. If you get sound but no picture it is a good sign your main is probably ok and your issue is with your T-con or panel.

Good luck!

[Poab]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

If you are getting backlight with the main board disconnected then your power supply is more than likely ok. The board you received is more than likely bad if you no longer gets the standby light. Also that red dot could be refraction from your camera and I wouldn't worry about it. As for your actual issue you stated that the backlight flashes once and seems to go away. Samsung sets will flash very bright and then dim out on a no signal screen, so maybe it actually is not turning back off but is dimmed and seems off. Here are a few things you can do in order to figure out if you do have a bad main board:
1) Double check the voltage on the fuse located on the T-con board. Do you get 12 volts on each side?
2) Plug in a dvd player via HDMI and double click input on your remote. It will automatically detect something plugged in or go to the TV input. So you may have to do this twice, wait 20 seconds and do it again. We are doing this to listen out for sound. If you get sound but no picture it is a good sign your main is probably ok and your issue is with your T-con or panel.

Good luck!

I check what I think is the fuse on the tcon board (picture attached), and got no voltage reading from either side.

No luck with any audio.

The flash I wrote about only happens if I disconnect the t-con board. If the t-con is connected, there is no flash.

[Nick's Tvs]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

If you are unable to get a voltage off either side of the fuse on the T-con board, then you may have a bad main board still.
However what I would do is remove the T-con board from circuit by removing the LVDS cable aka the ribbon from the main to the T-con and re-measure for 12 volts outgoing voltage from the main board on pin 1 of the ribbon connector CN1401. If you are able to get 12 volts output with the T-con disconnected, then that will show us that the T-con board is indeed faulty.
I would also try plugging in a device into the main board such as DVD player in an attempt to get sound out of the speakers. If you can't get sound or 12 volts out of that main board, then I would be looking at replacing that board again.

[CapLeaker]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

You have to look that the Tcon gets power. If the mainboard isn't sending power to the Tcon you got a faulty main board.

[Poab]

Re: Samsung UN60H6400AF Stdy Red Standby Light, but will not turn on

No voltage to the tcon from either the old or the new mainboard. I'll send off for another mainboard. It'll take about 2-3 weeks to get a new one. I'll update then.

Thanks for all the help. I realize these are super simple tips you're giving me. Just want to say thanks for taking the time to reply to all these newbie threads like mine.

Take care!