Samsung 60" LED blank screen and WILL NOT STAY OFF

[budwich]

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

"Old meter" = 123v
"New meter" = 94v

Guess I'm forced to revert back to the old one. I just don't want it to spark and blow the fuse again.

EDIT:
I just rechecked with the old meter and the voltages look correct now.

CP806 = 398v
CM861 = 402v
CM853 = 12.5v

I did not recheck with it in standby. I'm having trouble jumping PS_ON and working the multimeter at the same time. If it's necessary then I'll keep trying.

probably more of a dumb question... but what function are you using on your meter... AC or DC voltage?

[x_orange90_x]

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

probably more of a dumb question... But what function are you using on your meter... Ac or dc voltage?

dc

[budm]

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

"Old meter" = 123v
"New meter" = 94v

Guess I'm forced to revert back to the old one. I just don't want it to spark and blow the fuse again.

EDIT:
I just rechecked with the old meter and the voltages look correct now.

CP806 = 398v
CM861 = 402v
CM853 = 12.5v

I did not recheck with it in standby. I'm having trouble jumping PS_ON and working the multimeter at the same time. If it's necessary then I'll keep trying.

402V with LED connector in place?

[x_orange90_x]

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

402V with LED connector in place?

No, backlights were unplugged. Voltage jumps all over regardless of Standby when they are connected

[budm]

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

No, backlights were unplugged. Voltage jumps all over regardless of Standby when they are connected

That LED power supply boosted Voltage should not be there if the TV is in standby due to there will be no BL-ON to turn on the Boost converter. Something is not adding up.

[budm]

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

BTW, disconnect connector from the power supply board then check the resistance between chassis and each pin of the LED connector that goes to the LCD panel to see if any one of the pin shows resistance to the chassis or not.

[x_orange90_x]

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

BTW, disconnect connector from the power supply board then check the resistance between chassis and each pin of the LED connector that goes to the LCD panel to see if any one of the pin shows resistance to the chassis or not.

I just attempted that and the very first pin I touched blew the multimeter (fuse?). The TV is fine however. I undoubtedly believe at this point that there is a short occurring somewhere within one of the LED strips. TV face down, power on, I reconnected the backlights.. Raised the set to a 30° angle and watched for about 10 seconds and it was working perfectly. Raised it upright to 45° and it went haywire again. This makes me think that one of the connections between LED strips is somehow arcing on the chassis.

[budm]

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

How can you blow the meter fuse when the LCD connector is not in place? Are you testing the LED CONNECTOR that goes to the panel and that connector is NOT connected to the power supply board. There is NO Voltage on that LED connector when it is not connected to the power supply board.
Also do not test the resistance when the device is powered up.
https://www.badcaps.net/forum/attach...7&d=1578707669
Pull that LED connector with wires that go to the panel and then check the resistance of that connector with them wires on it, NOT the connector on the power supply board.

[x_orange90_x]

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

How can you blow the meter fuse when the LCD connector is not in place? Are you testing the LED CONNECTOR that goes to the panel and that connector is NOT connected to the power supply board. There is NO Voltage on that LED connector when it is not connected to the power supply board.
Also do not test the resistance when the device is powered up.
https://www.badcaps.net/forum/attach...7&d=1578707669
Pull that LED connector with wires that go to the panel and then check the resistance of that connector with them wires on it, NOT the connector on the power supply board.

Ok, well lesson learned.... Because I checked completely opposite of everything you said.

So, the meter I was using is toast now. The very-strange looking fuse that it DOES have inside looks fine/filament-unbroken.. so I reverted to the earlier questionable meter. However, checking resistance from each of the four wired pins of the LED connector, none had any change in resistance.

[budm]

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

Ok, well lesson learned.... Because I checked completely opposite of everything you said.

So, the meter I was using is toast now. The very-strange looking fuse that it DOES have inside looks fine/filament-unbroken.. so I reverted to the earlier questionable meter. However, checking resistance from each of the four wired pins of the LED connector, none had any change in resistance.

With reference to the chassis?
They should all show NO resistance, also did you test when you move the panel around?

[x_orange90_x]

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

With reference to the chassis?
They should all show NO resistance, also did you test when you move the panel around?

When you'd like me to check for alternate scenarios, it's easiest to know ahead of time so I can have that information ready. But no, I didn't move the panel around during this test. The meter I'm using (forcefully at this point) apparently isn't too trustworthy. For some reason it had an ambient resistance reading that bounced around heavily between 14ohms and 20ohms... Touching the two probes together brought it down to a more consistent 4ohms. Checking resistance of the plug did not vary at all from the 'ambient' readings. This i'd conclude, for the sake of this meter, that there is no resistance on the LED plug, at least at the time of measurement.

[nomoresonys]

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

Try with BOTH the backlight connector and cable to mainboard unhooked, plug the power cord into the powerboard, test voltage of pins on CNM803 compare them to the map/legend there printed on the board if that's all good it might be time to VERY carefully dig down to the backlights. The panel is VERY flimsy and easy to break, maybe check several youtube videos before hand, not exactly sure if backlights are the issue but these models are very prone to backlight failure.

[x_orange90_x]

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

Try with BOTH the backlight connector and cable to mainboard unhooked, plug the power cord into the powerboard, test voltage of pins on CNM803 compare them to the map/legend there printed on the board if that's all good it might be time to VERY carefully dig down to the backlights. The panel is VERY flimsy and easy to break, maybe check several youtube videos before hand, not exactly sure if backlights are the issue but these models are very prone to backlight failure.

I've replaced the backlights on this TV twice. First time was when I acquired it (they were bad), and the second time was because of the light spreaders falling off the new set. Shopjimmy RMAd them for me.

I'll check those voltages and report them back to you.

[x_orange90_x]

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

Both disconnected. Readings are with ONLY AC power cord plugged in.

1. B13V = 11.9v
2. PWM DIM = 4.01v
3. B13V = 12.2v
4. B14V = 12.1v
5. Vamp =12.1v
6. BLU ON = 3.52v
7. Vamp = 11.9v
8. GND
9. GND
10. GND
11. B5V = 5.6v
12. A5V = 5.6v
13. B5V = 5.55v
14. PS ON = 3.76v

I checked resistance again on the backlight cable to chassis while applying pressure all over the back of the chassis. Still found no change in resistance.

Also, because it's now a few pages back, I would like to reiterate that a boxelder bug was wrapped around two legs of the transformer when I first opened the TV (for this issue). I attached a picture to that post. No one said a word about it though, and I assumed it wasn't really an issue. I'm starting to wonder if maybe that was the real cause of this very strange problem. Could it have shorted the transformer, or something in circuit after it?

[budm]

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

I just attempted that and the very first pin I touched blew the multimeter (fuse?). The TV is fine however. I undoubtedly believe at this point that there is a short occurring somewhere within one of the LED strips. TV face down, power on, I reconnected the backlights.. Raised the set to a 30° angle and watched for about 10 seconds and it was working perfectly. Raised it upright to 45° and it went haywire again. This makes me think that one of the connections between LED strips is somehow arcing on the chassis.

So at this point, are you still getting the same reaction?

[x_orange90_x]

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

So at this point, are you still getting the same reaction?

I tried to reproduce this and couldn't. Checking resistance again and applying pressure on the chassis didn't reveal anything new either.

[R_J]

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

I had a 32" samsung with bad led's and one of the led's was shorted to the aluminum strip, so it was actually killing the led voltage. If I lifted the strip off the metal panel, the aluminum strip had the full led voltage on it.

[x_orange90_x]

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

I had a 32" samsung with bad led's and one of the led's was shorted to the aluminum strip, so it was actually killing the led voltage. If I lifted the strip off the metal panel, the aluminum strip had the full led voltage on it.

Was that a much older model by chance? I know that the way the LEDs are configured in my model wouldn't allow for a a single burnt out LED. The entire set of LEDs would remain off.

I understand that manufacturing practices often produce short-lived and defective products, but these strips are only ~14mo old and I used them at only 7/10 backlight.

Have any of you experienced poor quality and/or life from Shopjimmy's backlights? My only issue this far was with the previous set in which the spreaders started falling off.

[budm]

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

Shorted out LED in the series connected LED's will still allow the LED strings to light up, open LED will cause the whole LED not to light up. Too many shorted out LED will also cause the LED circuit shutdown. Shorted circuit in one of the LED string to the chassis will also cause the shutdown.
What kind of the LED strips/assemblies are used in your TV.
I run into panels that have one of the LED strip's wire nicked by the chassis and cause intermittent shorts circuits to the chassis.
BTW, do you have LED tester?

[R_J]

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

The Samsung I had for service was actually a 40" a UN40H5203 (mfg. 2014). When I first got it, It appeared dead. After a few checks I unplugged the leds and the tv turned on.
This was the only time I had seen a led string shorted to the chassis. Lifting the led string off the chassis restored the voltage but still no light. One led was all black around it. but after checking the led strings I found most of the led's on the 3 strings were bad. This was common for this model.
The reason I mentioned this was because I read this

TV face down, power on, I reconnected the backlights.. Raised the set to a 30° angle and watched for about 10 seconds and it was working perfectly. Raised it upright to 45° and it went haywire again