Samsung 60" LED blank screen and WILL NOT STAY OFF

[budwich]

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

I just replaced the 9v battery in it this morning before checking anything. And yes I thought it was odd that it read the voltage of the AA incorrectly.

ok... so with the new 9v battery in, what does your "AA battery test" now read?

[R_J]

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

I have NEVER had any multimeter cause a spark of any kind when checking voltage. What would be the point of having a multimeter for checking voltage if when you connected it, it created a short circuit creating a spark, across the voltage you are trying to check. The multimeter is defective.

[x_orange90_x]

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

I had it set exactly like in the picture above, except to 1000v for the higher voltage cap.

[budwich]

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

there is more to "metering" than having the leads plugged into the meter.... you also have to be on the RIGHT function. Odds are high that you had the meter on "current measuring" which is basically a "short" put on the leads... not good if you were trying to do a voltage measurement.

[x_orange90_x]

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

I just replaced the 9v battery in it this morning before checking anything. And yes I thought it was odd that it read the voltage of the AA incorrectly.

[nomoresonys]

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

Does your meter have a new battery in it? A new AA battery should read about 1.5 v.

[x_orange90_x]

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

This is the 16v cap just for example, but I did the same for the CP807 except I used the 1000v setting on the meter.

[budm]

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

If you connect the Volt meter probes to the plus and minus legs of the cap and it sparks, you have problem with the meter.
We will see your pictures of the meter and the setup.

[x_orange90_x]

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

I meant I checked the Ohms across the leads of the multimeter this morning.

When I checked the 16v cap I had the meter set to 20v, not Ohms. Likewise when I checked the cap you mentioned, I set the meter to 1000v (next lowest setting is 200v which is below the cap's rating).

[R_J]

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

What do you mean you checked the ohms on it this morning? Did you have the meter switched to ohms when you went to read the voltage across the capacitor?
As for the capacitor, it will be fine, but I suspect the fuse and maybe the bridge rectifier are gone also the pfc circuit may have been damaged.
The input resistance of the meter, is the mount of resistance the METER itself applies to the circuit. when checking voltage etc.

[x_orange90_x]

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

I checked the Ohms on it this morning and there was no difference in reading between all of the Ohms settings. It was a constant high out of range reading. I checked a AA battery and got about 3.3v which I thought was odd.

As far as the cap you had me check earlier, do you think I blew it?

[R_J]

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

That meter must just be acting like a piece of wire. because the only way for it to cause a spark like that is if the resistance between the + and - leads is next to 0Ω. Most meters have an input resistace of a few megohms, that is not low enough to have any effect on the circuit let alone cause a spark. I suspect this meter might have a MOV across the input and it is shorted.
Most meters have a model does the cen-tech have one?

[x_orange90_x]

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

How can connecting one lead to a circuit cause a spark? Is the meter connected to AC as in a bench meter like an old VTVM?
post either a picture of the meter or at least the make and model.

It's a Harbor Freight Cen-Tech meter, but I will post a picture of the configuration.

BTW, earlier when I tried checking the 16v cap on the board I had the positive lead on the positive leg of the cap and when I touched the negative lead to a ground screw it sparked... Same as when I touched it to the negative leg on the cap.

[R_J]

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

How can connecting one lead to a circuit cause a spark? Is the meter connected to AC as in a bench meter like an old VTVM?
post either a picture of the meter or at least the make and model.

[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.

[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

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

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

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.

[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?