Sony Bravia XBR-75X850D

[nomoresonys]

There's this, seems like they use the same firmware for the 850D and 940D: https://www.avsforum.com/threads/off...94522/page-677

[HS13]

My TV now had amber light and. green light blinking. I searched online and they said update the firmware but no luck to find it.

[nomoresonys]

It seems like there use to be a sticky thread above for firmware updates as in ones you put on usb and do the manual update. Being that many makers only keep them available on their sites for a limited time, maybe there was none but it sure would be a useful thread. If you do find it, hold onto it, in case it's ever needed again.

[nomoresonys]

Guess support ended in 2022, might be able to find it elsewhere, otherwise it looks like they want you to contact the product support team there and maybe you can get it that way: https://www.sony.com/electronics/sup...tware/00269731

[HS13]

Does anyone can help me to get the firmware Sony XBR-75X850D?

[m4a2t0t]

After some more digging I found out that the circle on the screen was actually the reset screen it just didnt show the text. Anyways, I left it on that screen with the USB plugged in and when I came back to it an hour later it was said the update finished. It now works properly. Thanks

[m4a2t0t]

Sorry about the delay in responding. I ordered a WORKING BM1 board and the unit now powers on, the problem is that it turns on by itself and then power cycles every 20 seconds. Backlights are on, the TV is displaying the sony logo then it reboots. I cannot turn it off. I tried updating the firmware but nothing is happening. This board come from and identical model. Is this a firmware issue or do I have another problem?

EDIT: Should I even attempt a firmware update when its power cycling?

WARNING: During the software installation process, please do not:

• Remove the USB device
• Turn off the TV
• Disconnect the TV from the power supply

I tried a forced factory reset (holding power and vol down until light turns green). It power cycled and now it has a large circle on the screen and it wont turn off. The Sony log and android animation no longer show up.

[Davi.p]

Re: Sony Bravia XBR-75X850D

it appears both main boards are bad, bad pic microcontroller software.. or at least its power supply.

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

I unplugged the DPS board and injected 3.3 into the connector on the G1 board to its left. Was I supposed to do it between the DPS and BM1 board? The bl_on and pwr_on signals come through each flex cable on that side.

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

Heres a picture of all 4 boards

[EazyBone]

Re: Sony Bravia XBR-75X850D

The main board picture clearly shows connections to the LED driver board. Pic 4 first post

I see 2 ribbons and 1 wire harness. Do the same jumping with any combination of those 3 connections disconnected until the bl turns on

[EazyBone]

Re: Sony Bravia XBR-75X850D

Give us a picture of the whole back to show all boards

The pic 4 in original posts clearly shows 2 ribbons and 1 wire harness connected to LED driver.

Disconnect any combination of ribbons/harness and do the same jump and try and get those bl to turn on. Disc from LED driver side and make sure PSU and main are never connected so a ribbon doesn't accidentally short while disconnected.

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

The main board only connects to the G1 power board. I thought you meant to remove the BL connectors from the GL2 power board (backlight board). I just removed the connector from the main board and jumpered the wires while both power boards were connected to each other.

I see nothing visibly wrong with anything on either power board. The TCON does get 12V and its present on both sides of the fuse.

[EazyBone]

Re: Sony Bravia XBR-75X850D

I tried with it disconnected and the BL board still turns on

Like the LED on the bl board turns on?

Have you taken both power boards out and inspected the backs for anything burnt. And when you jump tcon on, does the PSU send the 12v to tcon. 12v both sides of tcon fuse?
Need to rule out the PSU boards then can probably confirm is probably main board and can maybe run some tests on that

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

I tried with it disconnected and the BL board still turns on

[EazyBone]

Re: Sony Bravia XBR-75X850D

Make sure you have main board disc from LED driver also

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

When I do that I can hear the relay in the BL power board turn on and I get voltage at the BL pins but I dont see the backlight turn on.

EDIT: Actually I think I only did bl_on and pwr_on. I will go try it again with tcon_on as well.

EDIT2: When I jump those lines I get 72V on the backlight pins but the backlights do not appear to be on.

Does anyone know more about the power on signal in sony tv's? My pwr_on signal is 3.3v, its 3.3v immediately after plugging in power and stays the same when I press the power button. Am I missing something about that signal? Shouldnt it change when I press the button?

[EazyBone]

Re: Sony Bravia XBR-75X850D

Have you jumped tcon on/blon/power on/stby with main board disconnected? To then test voltages? Maybe verify this procedure before doing it as I'm newer, but does that turn bl on? Give tcon power etc

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

Added flow chart I was following

Is there anything else that could cause a dead set? The flow chart for the G boards is 2 steps.

Standby on DPS - check
Standby on BM1 - check

Means B board issue

Is the BM1 board I bought bad?

The BM1 board power_on line is at 3.38V and stays there when the power button is pressed. Should it go to 0?

BL_ON, PWR_ON, TCON_ON all missing. Power button has 3.3V and drops to 0 when power button pressed.

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

Sorry about the delay in responding. I tried uploading the service manual but it kept failing.
Try this https://file.io/aLjSiwodasQ7

If TCON VCC is not present will that cause any of this? I do not have BL_ON, PWR_ON TCON_ON when pressing the power button. If I jump power from standby 3.3 to BL_ON, PWR_ON I can hear the relay in the secondary PSU turn on and I have voltages present on the backlight pins.

I swapped the BM1 board and DSP board from units with cracked panels and still no change