Samsung 60" LED blank screen and WILL NOT STAY OFF

[R_J]

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

Maybe that's the problem, the pfc circuit is going into over voltage protection.

[budm]

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

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.

Turn the TV off and check the Voltage on that cap again to see what is shown on the meter.

[x_orange90_x]

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

Turn the TV off and check the Voltage on that cap again to see what is shown on the meter.

By turning it off you mean leave it plugged in but powered off, correct? If that's the case then I can't... Part of the original problem is that it WILL NOT stay off. It turns right back on within a second. Also turns on immediately upon plugging it in.

[nomoresonys]

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

Maybe you can reset the eeprom??

[nomoresonys]

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

What is the full model number?

[x_orange90_x]

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

what is the full model number?

un60fh6003fxza

[nomoresonys]

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

Not sure if there's a way to reset your model, there's some eeproms there if that's the problem, some whole mainboards boards too, as always make sure you check the numbers on the white sticker to ensure you get a match if you buy a mainboared: https://www.ebay.com/sch/i.html?_fro...acat=0&_sop=15

[nomoresonys]

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

You could try heating or cooling the eeprom (IC901) with a hairdryer or freeze spray/upside down can of duster, wait 15 seconds or so plug tv in, power on and see if it comes on even for a short while or anything changes.

[R_J]

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

You can try forcing the power supply OFF by disconnecting the main board plug CNM803. then short JP825 (PS_ON) to JP817/JP818 (GROUND). this will take the PS_ON line low and should place the power supply in standby mode. Then you can check if the main filter voltage drops to 160vdc
This would also confirm that the meter reads this voltage correctly. That 460v-480v on cp806 should be 380vdc. I would say it is your meter that can't reject the high switching frequency signal of the pfc boost circuit, thats why it is reading high.
Same for CM861 = 475v - 500v, This voltage is BOOSTED at high frequency by the led boost circuit, so it also is reading high.

[x_orange90_x]

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

You can try forcing the power supply OFF by disconnecting the main board plug CNM803. then short JP825 (PS_ON) to JP817/JP818 (GROUND). this will take the PS_ON line low and should place the power supply in standby mode. Then you can check if the main filter voltage drops to 160vdc
This would also confirm that the meter reads this voltage correctly. That 460v-480v on cp806 should be 380vdc. I would say it is your meter that can't reject the high switching frequency signal of the pfc boost circuit, thats why it is reading high.
Same for CM861 = 475v - 500v, This voltage is BOOSTED at high frequency by the led boost circuit, so it also is reading high.

So after getting it into standby you want me to check the voltages of all three of the caps again?

Don't know if it matters but this is an Auto Sensing meter.

[R_J]

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

This is just to check if the power supply can be turned off and is ok, this would then point to the main board as the likely problem. Just check the voltage across CP806 like you did before, it should be 160vdc. If the power supply is in its off state you should not have any voltage on CM861.
That auto sensing is likely auto ranging, so it picks the voltage range based on the voltage it sees. But these cheap meters are not ment for these type of circuits.

I have an LG/Goldstar meter that will show OL on the 1000vdc range when checking a plasma tv Vs voltage, my fluke checks it as 200vdc which is the correct voltage.

[x_orange90_x]

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

This is just to check if the power supply can be turned off and is ok, this would then point to the main board as the likely problem. Just check the voltage across CP806 like you did before, it should be 160vdc. If the power supply is in its off state you should not have any voltage on CM861.
That auto sensing is likely auto ranging, so it picks the voltage range based on the voltage it sees. But these cheap meters are not ment for these type of circuits.

I have an LG/Goldstar meter that will show OL on the 1000vdc range when checking a plasma tv Vs voltage, my fluke checks it as 200vdc which is the correct voltage.

Just tried to put it into Standby and it still won't. If I have the backlights unplugged there is a constant hum from the board and when I jump JP825 to JP817 the hum goes away, but as soon I stop jumping then it hums again. If I leave the backlights plugged in, they stay solid on when I jump it, but immediately start flashing again after I stop jumping it.

I left it jumped and checked them. This is what I got:
CP806 = 222v
CM861 = 362v

[R_J]

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

That meter is not measuring proper voltage. That 222V is actually 160V, So it is reading aproximately 62 volts high. So the pfc boosted voltage would be 460v-62v= 398vdc
CM861 3622v-62v = 300v which is close to the 297vdc for the backlights
I don't under stand "Just tried to put it into Standby and it still won't" you just proved that it does.
This power supply also may require that the BLU_ON (cnm803 pin6) be connected to ground to turn off the backlights.

[x_orange90_x]

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

That meter is not measuring proper voltage. That 222V is actually 160V, So it is reading aproximately 62 volts high. So the pfc boosted voltage would be 460v-62v= 398vdc
CM861 3622v-62v = 300v which is close to the 297vdc for the backlights
I don't under stand "Just tried to put it into Standby and it still won't" you just proved that it does.
This power supply also may require that the BLU_ON (cnm803 pin6) be connected to ground to turn off the backlights.

I have a hard time believing that it's off by 62v considering I checked the 16v cap yesterday at just under 16v.

As for the standby thing, the objective is to put it into standby and it stay there, isn't it? If I remove the jump it is instantly on again. If it comes right back on then it can't truly be in standby.

[R_J]

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

If I remove the jump it is instantly on again

Thats how it works. There is a pullup resistor on the PS_ON pin that turns ON the power supply when the main board is not connected. The only way to turn the power supply OFF is to have the PS_ON pin at a logic LOW. When the PS_ON is no longer grounded (Logic LOW), the pullup resistor on the power supply board, takes the PS_ON pin to 5volts (logic high) which turns the powersupply back ON.
As for the voltages measured by the meter, you better hope the reading is wrong or those capacitors are going to explode. CP806 is only rated for 450VDC. having 460~480vdc across them will cause them to fail

[x_orange90_x]

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

Thats how it works. There is a pullup resistor on the PS_ON pin that turns ON the power supply when the main board is not connected. The only way to turn the power supply OFF is to have the PS_ON pin at a logic LOW. When the PS_ON is no longer grounded (Logic LOW) the pullup resistor, the pullup resistor on the power supply board, takes the PS_ON pin to 5volts (logic high) which turns the powersupply back ON.

Ok that makes sense. Thanks for clarifying that.

So what do you make of this scenario now? I've never seen an issue like this before. I was reading about other model Samsung that the backlights would flash or strobe, and people simply had to cut a jumper on the power supply and the flashing stopped. I think it was JP852 for one range of sizes and JP854 for another range. My power supply has neither, but I also don't think that would be the issue here anyway.

[budwich]

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

you can do some simple tests of the meter using the wall plug as a "check". What do you read on the dc scale of your "new meter" when measuring the ac wall plug... that should indicate appropriately.

[R_J]

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

Based on your original post I would suspect the fault is with your main board. If the main board WAS working, it would issue the logic low and turn off the power supply, but it is not.
As for how the backlights operate without the main board connected, could be due to no PWM signal from the main board to properly control the led control ic.

[x_orange90_x]

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

you can do some simple tests of the meter using the wall plug as a "check". What do you read on the dc scale of your "new meter" when measuring the ac wall plug... that should indicate appropriately.

"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.

[x_orange90_x]

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

Based on your original post I would suspect the fault is with your main board. If the main board WAS working, it would issue the logic low and turn off the power supply, but it is not.
As for how the backlights operate without the main board connected, could be due to no PWM signal from the main board to properly control the led control ic.

Is there any diagnostic/repairs to be made to the main board or is it simply a replace-it scenario?

I'm not by any means an expert, but I really don't feel there anything wrong with the main board. I say this because of the following:

- With backlights unplugged, plugging in the TV it's in Standby

- Powering On (w/o BL), the TV operates normally ie I can change channels/inputs, volume, settings, everything works.

- Powers on and plays chime just fine, and also Powers off into Standby and stays as it should.

- I was able to even get into the Service Menu and Factory Reset as well as finish setup.

- Plugging in backlights INSTANTLY locks up the TV. Any menu that may have been on the screen disappears and every time it will display the No Signal message box. Even the 'snow' freezes on an analog channel.

Unless the main is trying to do something in regards to the backlights but can't?