Sony xbr-65x900c main board issues?

[jb_Bak]

Hey guys great forum glad to have found it. I bought a Sony XBR 65X900C cheaply because it didn't work. No signs of life at all not even a light/led. All I hear is a brief high voltage sound when I throw the power to it.

Didn't see any obvious signs of damage so right away started checking voltages. This is what I see:
Power Board Connector that goes to Main board
CN6401
Pin 01 NC
Pin 02 NC
Pin 03 "BL_ON": 0V
Pin 04 "N/C"
Pin 05 "STBY 3.3V": 3.5V
Pin 06 "GND": N/C
Pin 07 "AC_OFF" 3.5V
Pin 08 "BL_ERROR": 0V
Pin 09 "POWER_ON": 3.5V
Pin 10 "REG 12V": 12.75V
Pin 11 "REG 12V": 12.75V
Pin 12 "REG 12V": N/C
Pin 13 "REG 12V": 12.75V
Pin 14 "REG 12V": 12.75V
Pin 15 "REG 12V": 12.75V
Pin 16 "REG 12V": 12.75V
Pin 17 "GND": 0.001V
Pin 18 "GND": 0.001V
Pin 19 "GND":0.001V
Pin 20 "GND": 0.001V
Pin 21 "GND(TCON)": N/C
Pin 22 "GND(TCON)": 0.001V
Pin 23 "GND(TCON)": 0.001V
Pin 24 "TCON_ON": 0.000V
Pin 25 "TCON_VCC12V": N/C
Pin 26 "TCON_VCC12V": 0.001V
Pin 27 "TCON_VCC12V": -0.001V
Pin 28 "TCON_VCC12V": -0.001V

So no BL_ON or TCON ON or TCON VCC voltage at all. I believe both of these voltages come from the main board and not the power board correct? Also noticed it draws .14 amps AC from the outlet and when I unplug the power to the main board, amp draw goes to zero. The Sony labeled BGA chip is getting warm as is Q800 and Q801 on the power board. Checking Q800 and Q801 they seem fine I don't see any shorts and they voltage drop across them in diode mode seems OK. So I turned my attention to the main board. Lots of SMD fuses to check, all seem fine. It has 4 MOSFETS on them so checking the voltage at the output coils I see 1.5V, 3.3V, 5.0V and 12V so they are working but for some reason not getting the BL_ON and TCON back to the power board(or to the TCON board), also not outputting voltage at the connector on the main board that runs back to the power board. I also unplugged everything from the main board except the power board connector and still the .14A draw from the outlet.
Am I correct in the assumption the main board is bad?

Other things I checked that seem OK:
TCON board fuse
Reset the ribbon cables
Power board diodes and voltages on the primary side are all there
I have VLED_VCC at 40V out of the backlight driver board. I think this is correct? No visible backlight though.

Anything else I could be missing before I go ahead and buy a new main board? I have a rework station and am comfortable with replacing things on the main board just can't find the issue besides the warm Sony X1 CPU chip which I am assuming is the fault here.

[William1967]

Re: Sony xbr-65x900c main board issues?

Most of the times the EMMC has a problem, the bootsoftware in in there and the EMMC has a limited life...

[jb_Bak]

Re: Sony xbr-65x900c main board issues?

Are you talking about this little nand on here? If so I use to reprogram these to unlock ipads. I have a friend who still has the programmer. Where would I find a good image to write to it? I suspect it would have to be pulled from a working board?

[William1967]

Re: Sony xbr-65x900c main board issues?

Yes that is the one. The problem is that the website where I used to download the software is offline, another problem is that after reprogramming the Netflix app does not work anymore.

[andrewc]

Re: Sony xbr-65x900c main board issues?

Yes that is the one. The problem is that the website where I used to download the software is offline, another problem is that after reprogramming the Netflix app does not work anymore.

May I know the URL link you download the dump from? I am also having an issue booting my Sony TV?

[nomoresonys]

Re: Sony xbr-65x900c main board issues?

Most of the times the EMMC has a problem, the bootsoftware in in there and the EMMC has a limited life...

William does this mean that the chip will go dead after a certain number of engagements, if I understand it correctly or do you mean they just wear out after a while? thanks.