Samsung 60" LED blank screen and WILL NOT STAY OFF

[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

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

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

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

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 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).

[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

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.

[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

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.

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

[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.

[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?

[x_orange90_x]

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.

I think you're correct. I haven't used it in about a year but last time I did it worked ok.

Anyways, I replaced the fuse and it works again, so I'm back to where I was before the big bang. Unplug backlights and watch for image on screen, plug in backlights and screen flashes. Also, just let it sit flashing for a minute and the screen got progressively darker. Seems like there's a big under voltage happening.

I have another multimeter, but it's not turning on. I'm going to try and get it working and see if I can get the readings you asked for earlier.

[x_orange90_x]

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

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

No way in hell I'm using that meter again. I'm going to try and get my old Micronta working.

BTW it had the new battery in it when I checked the AA and when it sparked on the PSU. I think it's just junk now.

[budwich]

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

the "aa battery test" isn't going to do much other than trying to understand what happened with your meter. IF you aren't reading proper low voltage then, yes, give up on the meter. But if your other meter is broken, I wouldn't necessarily jump to the conclusion that its the answer unless you do some test trial before hand.

[x_orange90_x]

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

the "aa battery test" isn't going to do much other than trying to understand what happened with your meter. IF you aren't reading proper low voltage then, yes, give up on the meter. But if your other meter is broken, I wouldn't necessarily jump to the conclusion that its the answer unless you do some test trial before hand.

I got the other meter working and successfully checked the cap voltage on the TV. I will post all of the results when I'm finished.

Edit:

Here are the readings. I checked these with power on and the backlights UNPLUGGED. I tried checking with the backlights but obviously the voltages were erratic due to the flashing on and off.

1. B13V = 11.66v
2. PWM DIM = 1.67v
3. B13V = 11.62v
4. B13V = 11.6v
5. Vamp = 11.55v
6. BLU ON = 5.32v
7.Vamp = 11.46v
8. GND
9. GND
10. GND
11. B5V = 5.7v
12. A5V = 5.66v
13. B5V = 5.63v
14. PS ON = 4.06v

Caps:

CP806 = 460v - 480v
CM853 = 11.65v
CM861 = 475v - 500v

[budm]

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

"CP806 = 460v - 480v"
What did you use for meter ground?
No way you can have 480VDC on that 450V rating cap. The Voltage MEASURED BETWEEN THE TWO LEGS OF THE CAP should be around 380VDC, the PFC circuit would have gone into shutdown if the Voltage really that high.

[x_orange90_x]

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

"CP806 = 460v - 480v"
What did you use for meter ground?
No way you can have 480VDC on that 450V rating cap. The Voltage MEASURED BETWEEN THE TWO LEGS OF THE CAP should be around 380VDC, the PFC circuit would have gone into shutdown if the Voltage really that high.

Every cap was measured between legs. The main plug was measured with a ground screw.

Edit:
Checked again, still got 460v-480v on it. I also checked WITH backlights plugged in and flashing and got 159v with drops every time it flashed.