Samsung 60" LED blank screen and WILL NOT STAY OFF

[x_orange90_x]

I am not sure of the model number because it's wall mounted and I haven't had a chance to take it down yet. It is a Samsung 60" LED NON-SMART TV.

Last night while watching TV (streaming Netflix from my PC), the screen went completely blank. The backlights are still on, but it displays no image and has no sound. I can't bring up the menu or visually see it do anything. Even stranger is the fact that it WILL NOT stay powered off. Pressing the power button on the remote or TV turns it off for about half a second and then it comes right back on. The backlights will shut off for that fraction of a second, but immediately come back on, still displaying no picture. I unplugged it for about 30 minutes, and as soon as I plugged it back in it came on with backlights.

When I got the TV I replaced the backlights (ordered new from ShopJimmy). I haven't had any issues until now. I also keep the backlights at 15 out of 20.

I've never seen this kind of issue before and so I don't have any idea where to start. Seeing that it refuses to stay powered off I'm suspecting the power supply board, but generally that would cause a set to not stay on.

Any ideas?

Note: I only have two sources plugged into it: HDMI from my PC, and a coaxial antenna. I DID try disconnecting the HDMI from the PC but still had the same symptoms.

[nomoresonys]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

Some resets in that thread you can try: https://www.badcaps.net/forum/showth...=samsung+reset

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

Some resets in that thread you can try: https://www.badcaps.net/forum/showth...=samsung+reset

I will try this when I get home. Thank you!

[budm]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

What is the model number of the TV?

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

What is the model number of the TV?

I'm going to try the reset when I get home, and if it don't work I'll take it down and post the model number.

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

The reset did not work. Haven't taken it off the wall yet to see the model number.

[nomoresonys]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

Looks like you will need to take the back cover off and look around.

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

What is the model number of the TV?

It's a
UN60FH6003FXZA

If it's the main board that is bad, I found a used one on eBay for $43 and an additional $5 off coupon. Because the backlights are on and the TV powers itself on, it sounds like the main board is faulty.

Does it sound likely?

[budm]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

You will have to do more testing such as Voltage testing but at this point I cannot tell you where to check since we do not have pictures of the boards and the whole backside of the TV showing all the boards.

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

I've finally gotten around to this.

When I plug in the power cord the TV is on and backlights are instantly lit, as I said before. If I unplug the power from the main board the backlights flash on and off repeatedly. Unplugging anything else makes zero difference... Backlights stay lit but no image.

[neilc6]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

Those F model years have bga issues and arcing connectors. Search ebay seller kcrownie for repair services.

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

Those F model years have bga issues and arcing connectors. Search ebay seller kcrownie for repair services.

I don't know what any of that means. Can you elaborate on it and what exactly is wrong/needs repair?

[neilc6]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

Dont see your model listed in the ones with repair services available. Sounds like a few issues. Backlights should stay on with main board disconnected. You need to report the voltages at the connector. Is the PS_ON signal going high by itself? What happens if you disconnect the button board if it has one. Does the tv stay off?

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

Dont see your model listed in the ones with repair services available. Sounds like a few issues. Backlights should stay on with main board disconnected. You need to report the voltages at the connector. Is the PS_ON signal going high by itself? What happens if you disconnect the button board if it has one. Does the tv stay off?

I will check the PS_ON voltage tomorrow. Please advise what the voltage should be and in what condition. Also, I only have a single rocker-button which controls everything on the set itself. There is not any other hardware controls.

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

I tried unplugging the rocker button and nothing changes. Unplug the TV and plug it back in and it instantly lights up again. I went to check the voltages and found something very interesting. First, I found a dead bug shorting out something on the PSU (picture attached). I removed the bug hoping that was the problem, but I think instead it caused other issues. Secondly, now that I've removed the bug, the screen is off, but if I tap on the TV the backlights go on and off. There is definitely a short somewhere, and I'm really hoping it's not the backlights.

As for checking the voltage..I can't get any reading from any pin. I tried checking a 16v cap just to see if it had voltage, but instead of giving me a reading, my negative probe sparks against anything I ground it to, be it the negative leg of the cap or a ground screw.

I'm really unsure at this point.

Here is a short video I made showing the backlights going on and off

https://youtu.be/dmMonap_Gtw

UPDATE 2:
I decided to unplug the backlights and try the old flashlight test. Sure enough I see an image. So with the image on screen I plugged the backlights back in and the following video is what happened. First the image is full but the brightness pulsates for a few seconds, then it just flashes on and off.

https://youtu.be/bOoy0Z9Vkc0

Bad cap on the power supply?

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

With the backlights unplugged I can navigate through the menu and change settings (too dark to confidently do anything tho ��), but as soon as I plugged them in the TV locks up and I can't access menus, change channel, volume, etc.

Every time the backlights flash I can hear something on the PSU... I'm guessing it's a very quiet relay or transformer or something. It's acting like there's not enough power to keep the set functional AND the backlights on together.

[R_J]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

First check the voltage ACROSS the main capacitor CP807, It should be around 160vdc in standby (tv off) and around 380vdc with the tv ON. This will confirm the pfc circuit is working.

Then check the voltage on CNL802 (you need to monitor this voltage when the tv is first turned on)
Pins 1&2 should be around 297 volts
pins 4 or 6 should be around 140 volts
pins 8&9 should be around 10~20 volts

You may want to remove the power supply board and check the solder connections on tms801cs (near the roch) and any of the transistors mounted on the heatsinks.

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

Thanks for the response! I will check those, however I won't be able to get a standby voltage for CP807 because the TV is never off while plugged in.

EDIT:
Tried to check CP807 with the power on and got a big spark. Now the TV does NOTHING. No Standby light, no flashing screen... NOTHING.

[R_J]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

Post a picture of your meter and how the probes were connected. and post a picture of the board focusing on CP807. I suspect you had your meter probes in wrong. Or you slipped and shorted CP807 to JP848
There is no other reason this would happen.
You likely blew the main fuse and maybe damaged the bridge rectifier, check the four diodes in the bridge.

[x_orange90_x]

Re: Samsung 60" LED blank screen and WILL NOT STAY OFF

No picture currently, but I can assure you I had the black negative probe attached to the negative leg of the cap, and the red positive probe on the positive leg of the cap.

Also, I had the negative attached to COM on the multimeter, and the positive attached to the 1000v lead on the multimeter.

As I mentioned a couple of posts back, trying to check the 16v cap I got sparks on the negative lead. I'm not sure if it's an issue with my multimeter or am overall short in the set. I do have another multimeter, but I'm trying to get it working atm.