UE48JU6000K Main Board BN94-09749Q

[alltvrepairs]

Hi,
I need to replace this mainboard.
Exact model UE48JU6000KXZT
Panel: CY-GJ048HGLV4H

Found several cheaper 'looking exact similar' for same model but may use different panel.
Example:
BN94-09309T For Samsung UE40JU6000K
BN94-10703M FOR SAMSUNG UE43JU6000K TV SCR:CY-GJ043HGAV1H

Not sure if I can see a picture with any of these that use different screen. If so I could adjust from service mode.

Any hints on this model please?

[Storyteller12]

Re: UE48JU6000K Main Board BN94-09749Q

Couldn't you just replace eeprom from your non working board to one of those you mentioned. Shouldn't matter if different panel then.

[alltvrepairs]

Re: UE48JU6000KXZT ver: 01 Main Board BN94-09749Q

Hi again,

So the replacement main board arrived.
Original BN94-09749Q, replaced with BN94-09309U for UE48JU6000K

Tv switched On but backlight flickered for a second and went off while TV still works fine. Have confirmed this by switching on the backlights with my tester.
Have swapped the Eeprom from the original board but still same.
In Service mode changed the panel type according the the panel sticker (48A6AU2VJ). With this new setting the backlight do not start at all.

Disconnecting the main board the backlights switch on fine with 106v across both connectors. Tried also removing LVDS connectors but no difference.

So am a bit puzzled now. Is there a setting in service mode to control backlights please?

[nomoresonys]

Re: UE48JU6000K Main Board BN94-09749Q

what do you get with the tcon unhooked from mainboard?

[Storyteller12]

Re: UE48JU6000K Main Board BN94-09749Q

+1 nomoresonys

Also need to take measurements from the connector going from the power supply to mainboard. I’m sure you will find a different voltage somewhere on there

Could be a bad mainboard

[alfatv]

Re: UE48JU6000K Main Board BN94-09749Q

Can you measure voltages at LED connector when good and no-good?
Black wire of multimeter at chassis ground.

[alltvrepairs]

Re: UE48JU6000K Main Board BN94-09749Q

what do you get with the tcon unhooked from mainboard?

I have backlights on all the time with tcon disconnected from main board. But no hacklight if removing any 1 or both of the panel connectors.
Trued the trick on eaxh connector with small piec of insulator at multilple positions but no success.

Switched from service menu to another clise versions but the closest i get a split second backlights on and off agsin.

[alltvrepairs]

Re: UE48JU6000K Main Board BN94-09749Q

+1 nomoresonys

Also need to take measurements from the connector going from the power supply to mainboard. I'm sure you will find a different voltage somewhere on there

Could be a bad mainboard

I have replaced the mainboard as original was defective.
Note that replacing the SPI made no difference and the data loaded in service mode for panel type, hours on etc was not changed. Hence these are stored probably in another flash.

Re voltages, i don't have service manual but voltages seem to measure ok.

[nomoresonys]

Re: UE48JU6000K Main Board BN94-09749Q

how bout a picture of the whole back as to see how everything is connected.

[nomoresonys]

Re: UE48JU6000K Main Board BN94-09749Q

maybe look for a fuse to test on the panel driver board.

[nomoresonys]

Re: UE48JU6000K Main Board BN94-09749Q

can also test the capacitors on the panel driver board, can test for shorts, can use continuity mode, can also check for very low ohms with ohm mode and a probe on each side of the cap, heres Bob doing some cap testing on a pc board: https://www.youtube.com/watch?v=lpRgRDbhOPI

[Storyteller12]

Re: UE48JU6000K Main Board BN94-09749Q

I have replaced the mainboard as original was defective.
Note that replacing the SPI made no difference and the data loaded in service mode for panel type, hours on etc was not changed. Hence these are stored probably in another flash.

Re voltages, i don't have service manual but voltages seem to measure ok.

I know you replaced it but it doesn't mean you didn't get a defective one.
That's why I said take measurement from the main board plug that goes to the power board. Do this with each main board plugged in and see if there's any difference

[alltvrepairs]

Re: UE48JU6000K Main Board BN94-09749Q

I know you replaced it but it doesn't mean you didn't get a defective one.
That's why I said take measurement from the main board plug that goes to the power board. Do this with each main board plugged in and see if there's any difference

I will take up measurements as you suggested. However the original board has a fault of trying to boot and recycles continuously. I am suspecting the TCON software does not match the one of the replacementr board. IN Service mode I fha ve option to reload the firmware of the TCON but made no difference. Switched off Wathdog as well just in case but still no luck.

[nomoresonys]

Re: UE48JU6000K Main Board BN94-09749Q

thinking it might be a panel issue, did you try the tests in link, post #11.

[alltvrepairs]

Re: UE48JU6000K Main Board BN94-09749Q

thinking it might be a panel issue, did you try the tests in link, post #11.

Hi,
I have seen #11 already. I do not think it there is a panel problem because if supply the LEDs with an external current source, the screen is lit 100% and works perfectly. The 2 TCON blue LEds are lit fine.

My understanding is that the Baclight current sense signal is out of range as of its internal range as set in the new mainboard. ... if this makes sense at all!

[alfatv]

Re: UE48JU6000K Main Board BN94-09749Q

#6?

[alltvrepairs]

Re: UE48JU6000K Main Board BN94-09749Q

#6?

At switch ON the backligts are lit for 0.25 of a second so can't measure it as it goes to 0 immediately. With the TCON to Mainboard LVDS disconnected the voltage is 106v pair 1 and 106v pair 2. So this also tells me that both LED sets are good. Usually a problematic LED will show voltage discrepancy.

[alfatv]

Re: UE48JU6000K Main Board BN94-09749Q

At switch ON the backligts are lit for 0.25 of a second so can't measure it as it goes to 0 immediately. With the TCON to Mainboard LVDS disconnected the voltage is 106v pair 1 and 106v pair 2. So this also tells me that both LED sets are good. Usually a problematic LED will show voltage discrepancy.

With mainboard disconnected
Measure both sides of LEDs against ground. That's 4 measurements.

Then the same with mainboard connected and TV running, LEDs off
Another 4 measurements.

Also do #5 when TV is running

[nomoresonys]

Re: UE48JU6000K Main Board BN94-09749Q

Hi,
I have seen #11 already. I do not think it there is a panel problem because if supply the LEDs with an external current source, the screen is lit 100% and works perfectly. The 2 TCON blue LEds are lit fine.

My understanding is that the Baclight current sense signal is out of range as of its internal range as set in the new mainboard. ... if this makes sense at all!

ok, you're the expert, I'll just leave you with this little tip, the panel is not the backlights, 2 different things.

[alltvrepairs]

Re: UE48JU6000K Main Board BN94-09749Q

With mainboard disconnected
Measure both sides of LEDs against ground. That's 4 measurements.

Then the same witboard connected and TV running, LEDs off
Another 4 measurements.

Also do #5 when TV is running

Have done as requested tks.
If i remove the Blu_pwm pin the backlights are on full intensity.