Sony Bravia XBR-75X850D

[xedap1998]

Re: Sony Bravia XBR-75X850D

This TV does not power on. No standby or power light

The left side power board seems to be the issue. The large primary caps have .9v on them. The rectifier has 2.5V across the AC terminals.

On the first board (left most board), If I measure from Neutral to the rectifier bottom AC pin I get 2.3V, top pin 150mV, Live to bottom pin 120V, live to upper 122V.
If I compare it to the second board I get Neutral to bottom 1.1V, upper 121V, Live to bottom 121V, upper 1.1V.

Most likely the board D is bad....the EMMC chip on board D need to be replaced

[nomoresonys]

Re: Sony Bravia XBR-75X850D

Added backside picks of power supplies

I went through the flow chart test and im stuck on the last part of the U-COM failure test

If BL_MUTE (R9090) is 0V, Check BL_ON IC9017 pin 18. Is voltage greater then 3V

R9090 is 3.4V and pin 18 is 0v. Not sure what im supposed to do. Should i continue to the DDCON tests?

I added the pic of the IC. R9090 is connected to the 3 pin IC to the right of the 20 pin IC9017

Can you post the manual or flowchart, whatever you're working with, so we can see what you are referring to.

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

DDCON CHECK

3.3v_main, 1.1v_sagi, 1.5v_sagi,5v_main, 1.0v_hdmi, 1.8v_tu, 1.0V_muf, 5.0V_vbus, 1.5v_ddr, all present

The DDCON check was in 2 parts for some reason. IC9001 Vcc on C9033, greater than 12V - Yes, 12.7. Check Vcc on C9061, greater than 4V - Yes, 4.8V. Check enable pin on IC9010 pin 1, greater than 2.5V, yes, 4.8V. If yes, change DDCON IC9009. That IC is for 1.5V_DDR and it is present on the large coil on the output. Why would it have me change that IC if its outputting a voltage?

None of these tests actually had me check the output of any of these ICs. Check input, greater than 12V? check enable pin, greater than 2.5V? Not one check of the actual output voltage. According to this flow chart I need to swap every DDCON and LDO even though they are working fine.

LDO CHECK

1.8V_agi, 2.5v_agi, 1.05v_muf_a, all present

There is nothing left to test for no power. Am I looking at a set with bad firmware or SoC on one of the boards? Or is it an issue with that BL_MUTE signal being 3.5v?

[lotas]

Re: Sony Bravia XBR-75X850D

IC9017 is a programmed microcontroller from MICROCHIP and it contains its own firmware.

[nomoresonys]

Re: Sony Bravia XBR-75X850D

.

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

Added backside picks of power supplies

I went through the flow chart test and im stuck on the last part of the U-COM failure test

If BL_MUTE (R9090) is 0V, Check BL_ON IC9017 pin 18. Is voltage greater then 3V

R9090 is 3.4V and pin 18 is 0v. Not sure what im supposed to do. Should i continue to the DDCON tests?

I added the pic of the IC. R9090 is connected to the 3 pin IC to the right of the 20 pin IC9017

[nomoresonys]

Re: Sony Bravia XBR-75X850D

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

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

I thought the left one was the main power board but it isnt.

I will go through the flow chart checks tomorrow and see if that narrows it down

[petehall347]

Re: Sony Bravia XBR-75X850D

what you describe is looking like whatever drives the relay isnt doing its job for some reason .

[m4a2t0t]

Re: Sony Bravia XBR-75X850D

The rectifier wont work until RL801 is turned on, correct? Im actually reading 12.7Vdc on both sides on the relay. Shoudlnt I see 12.7 across it, or 12.7v on one side and 0 on the other, when its on? I did remove it from the board and it turns on when 12V is applied and the switch side has about .5 ohms.

[m4a2t0t]

This TV does not power on. No standby or power light

The left side power board seems to be the issue. The large primary caps have .9v on them. The rectifier has 2.5V across the AC terminals.

On the first board (left most board), If I measure from Neutral to the rectifier bottom AC pin I get 2.3V, top pin 150mV, Live to bottom pin 120V, live to upper 122V.
If I compare it to the second board I get Neutral to bottom 1.1V, upper 121V, Live to bottom 121V, upper 1.1V.