Samsung UN55D6005SF

[bleed4me]

Re: Samsung UN55D6005SF

Ok so we at least know that voltage is correct. Which voltages am I missing here?

[budm]

Re: Samsung UN55D6005SF

PS-ON: <1V (typ.) = OFF, >2V (typ.) = ON

[bleed4me]

Re: Samsung UN55D6005SF

The BL-ON pin on the power supply board has pull-up resistors for performing power supply board self test, when the power supply board is connected to the main board, the main board will keep the BL-ON line low (<1V), when the TV is turned on then the main board allow the BL-ON to high turn on the backlights circuits.
So at this point you have more than just BL-ON problem on the main board some where. If you check the Voltages at the power supply connectors you will find that some other control Voltages are not there either.

Thank you for explaining that! I never understood how that worked but it makes sense now. Much appreciated.

Does the PSON voltage need to be in the 5v range as well?

[budm]

Re: Samsung UN55D6005SF

Ok so BL-ON disconnected and everything back into place when i power on the TV it flashes the splash screen and turns off.
so no change on that...

I must ask though if BL-ON is already at a voltage of 0 why would disconnecting it make any difference?

The BL-ON pin on the power supply board has pull-up resistors for performing power supply board self test, when the power supply board is connected to the main board, the main board will keep the BL-ON line low (<1V), when the TV is turned on then the main board allow the BL-ON to high turn on the backlights circuits.
So at this point you have more than just BL-ON problem on the main board some where. If you check the Voltages at the power supply connectors you will find that some other control Voltages are not there either.

[bleed4me]

Re: Samsung UN55D6005SF

Try having just the BL-ON wire disconnected and everything are back in place so you will get backlights, and if there is no other problem any where else then you should see image and sound and all other functions of the TV, if not then you have more than just no BL-ON signal.

The only way I can keep the backlights on is if the mainboard is disconnected from the power board.

[bleed4me]

Re: Samsung UN55D6005SF

Try having just the BL-ON wire disconnected and everything are back in place so you will get backlights, and if there is no other problem any where else then you should see image and sound and all other functions of the TV, if not then you have more than just no BL-ON signal.

Ok so BL-ON disconnected and everything back into place when i power on the TV it flashes the splash screen and turns off.
so no change on that...

I must ask though if BL-ON is already at a voltage of 0 why would disconnecting it make any difference?

[budm]

Re: Samsung UN55D6005SF

Try having just the BL-ON wire disconnected and everything are back in place so you will get backlights, and if there is no other problem any where else then you should see image and sound and all other functions of the TV, if not then you have more than just no BL-ON signal.

[bleed4me]

Re: Samsung UN55D6005SF

Anybody have some insight on how to trouble shoot the mainboard to fix BLU_ON signal?

Just a thought but could one simply find another 5v triggered pin and jump it?

[bleed4me]

Re: Samsung UN55D6005SF

It's looking more like you have a mainboard fault with the BLU_ON signal not being activated.

Thank you sir for sharing your knowledge. Now that we know its the mainboard question is can it be fixed on a component level?

[dick_barton]

Re: Samsung UN55D6005SF

It's looking more like you have a mainboard fault with the BLU_ON signal not being activated.

[bleed4me]

Re: Samsung UN55D6005SF

So the backlights do come on and stay on? You will NOT see any image on the screen when T-CON is not connected to the main board.

The only time the backlights will stay on as well as the tv is if the mainboard is disconnected from the power board. All the other options i have tried just makes the tv power down.

[bleed4me]

Re: Samsung UN55D6005SF

So with the Tcon disconnected the set stays powered up?. Can you post a photo of the Tcon?

Sorry i was wrong about that. If the tcon is disconnected from the tcon board the backlights will flash and power down.

[bleed4me]

Re: Samsung UN55D6005SF

BLU On = 0V means the backlights are not being switched on.
If you disconnect the mainboard from the power supply do the backlights come on and stay on?

Correct if you disconnect the mainboard from the power supply the backlights do com on and stay on.

[bleed4me]

Re: Samsung UN55D6005SF

Sorry I was at work. So I retested everything just to make sure and here are the results...

If I disconnect the mainboard the tv will stay on and the backlight is on.

If I disconnect the tcon board from the mainboard the tv will flash ( no spash logo ) and shut down.

If I disconnect one of the tabs on the tcon board that go to the panel when i power it on I get half the screen with the splash logo and the other side is white but has like a green ghosting that fades and turns off. If I test the other tab I get the same results just on the other side.

All of these were tested one by one.

[budm]

Re: Samsung UN55D6005SF

If I disconnect the tcon board the tv will power on but with no Samsung splash and stay on.

So the backlights do come on and stay on? You will NOT see any image on the screen when T-CON is not connected to the main board.

[budwich]

Re: Samsung UN55D6005SF

If I disconnect the tcon board the tv will power on but with no Samsung splash and stay on.

can you clarify... you are doing one cable at a time NOT completely disconnecting all the tcon to panel cables at the same time... right? The screen should show up white on the disconnected side "normally".

[dick_barton]

Re: Samsung UN55D6005SF

So with the Tcon disconnected the set stays powered up?. Can you post a photo of the Tcon?

[bleed4me]

Re: Samsung UN55D6005SF

If I disconnect the tcon board the tv will power on but with no Samsung splash and stay on.

[budwich]

Re: Samsung UN55D6005SF

since you get backlights on with the main board disconnected, that indicates the problem is either with the main board or something it "sees" isn't good and as a result, after the "flash and splash" then shutdown. You can try unplugging, one at a time, the tcon to panel cables to see if this changes the result. This may check whether the issue is with the panel and / tcon depending and what the outcome is. Of course, do the cable disconnecting / reconnecting with the power off. :-)

[nomoresonys]

Re: Samsung UN55D6005SF

It looks like the mainboard isn't sending the BLU-ON signal to the powerboard.