Sony XBR-55X900F No picture, no sound no backlight

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

There may be several very small fuses on the mainboard, check them for continuity.

I checked as many as i could find and they were good. Gonna take a closer look tomorrow under the microscope at work though.

Also, the big caps in the previous picture all had 12V on them.

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

Can do a quick check on main's internal power rails

• SPDIF light on?
• USB has power?
• All big inductors on main show some typical voltages? ~1V for CPU. ~1.5 DRAM, ~1.8 + 3.3 eMMC, 5V near USB

I actually have this board from a cracked screen salvage from a couple of years ago. Too bad you are in CA haha ($$$ shipping from US)

0V on all circled inductors. 0V at USB. No light on the board at all.

[howardc64]

Re: Sony XBR-55X900F No picture, no sound no backlight

Can do a quick check on main's internal power rails

• SPDIF light on?
• USB has power?
• All big inductors on main show some typical voltages? ~1V for CPU. ~1.5 DRAM, ~1.8 + 3.3 eMMC, 5V near USB

I actually have this board from a cracked screen salvage from a couple of years ago. Too bad you are in CA haha ($$$ shipping from US)

[nomoresonys]

Re: Sony XBR-55X900F No picture, no sound no backlight

There may be several very small fuses on the mainboard, check them for continuity.

[Nicktronic]

Hey,

I have this subject TV and when I plug it in I don't get a picture, backlight or sound. The remote and power buttons don't seem to do anything. I've metered the signals on the following after plugging in the TV;

Power Supply Board Connector CN6401 between PSU, MB, TCON

PIN 1 - BL_ERR - 0VDC
PIN 2 - BL-ON - 0VDC
PIN 3 - POWER_ON - 3.47VDC
PIN 4 - N/C
PIN 5 - STANDBY3.3V - 3.50VDC
PIN 6 - N/C
PIN 7 - GND - 0VDC
PIN 8 - GND - 0VDC
PIN 9 - N/C
PIN 10 - REG12 - 12.69VDC
PIN 11 - REG12 - 12.69VDC
PIN 12 - N/C
PIN 13 - REG12 - 12.69VDC
PIN 14 - REG12 - 12.69VDC
PIN 15 - REG12 - 12.69VDC
PIN 16 - REG12 - 12.69VDC
PIN 17 - GND - 0VDC
PIN 18 - GND - 0VDC
PIN 19 - GND - 0VDC
PIN 20 - GND - 0VDC
PIN 21 - N/C
PIN 22 - N/C
PIN 23 - GND - 0VDC
PIN 24 - GND - 0VDC
PIN 25 - N/C
PIN 26 - TCON_ON - 0VDC
PIN 27 - TCON_VCC12 - 0VDC
PIN 28 - TCON_VCC12 - 0VDC

Power Supply Board Connector CN6601 between PSU, LED Driver

PIN 1 - VLED_VCC - 26.04VDC
PIN 2 - VLED_VCC - 26.04VDC
PIN 3 - VLED_VCC - 26.04VDC
PIN 4 - VLED_VCC - 26.04VDC
PIN 5 - N/C
PIN 6 - N/C
PIN 7 - VLED_GND - 0VDC
PIN 8 - VLED_GND - 0VDC
PIN 9 - VLED_GND - 0VDC
PIN 10 - VLED_GND - 0VDC
PIN 11 - SENSE_GND - 0VDC
PIN 12 - BL_CTRL - 0VDC
PIN 13 - N/C
PIN 14 - 12VLD - 12.69VDC

From my limited understanding, the MB has provided the Power On command to the PSU to bring up all supply voltages, but then.....nothing. No backlight command, no tcon command. Safe to say the MB is the issue and to replace it? Is there anything else I should check before I just replace the MB?

I read in another post with similar issues that BGA re-work might be required?

https://www.badcaps.net/forum/showthread.php?t=94067

Has anyone had success with this?

Thanks!