Sony bravia Psu (A-1660-720-B) schematic needed

[6ot4hr]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

Are there copper traces from GND leading to those pins?
Can we see good clear pictures?
BTW, the 12Vdc feeding the Balancer board is present?
The ICs on the Balancer board are for the comparator circuit for error detection circuit.

Yes, seem they all should be connected to GND. My bad, wrong rabbit hole.

[budm]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

They do that when one of the comparator (LM2903, Open Collector output) is not being used.
https://cdn.badcaps-static.com/pdfs/...e2de368a4d.pdf

[6ot4hr]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

BTW, if you disconnecting the small cable (the one with FB,LD, 12V) to the Balancer board, do you get error lights.

No error codes, even after disconnecting that connector. But the voltage went from 6V back to 12V on the 12V pin (measured on PSU)

[budm]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

That 12V should stay at 12V with load (the comparator circuit on the Balancer board) or without the load (connector removed form the Balancer board).
That 12v is fed from VCC_12V (PAGE 40 of the service manual).
The VCC_12V is generated by the transformer T6101 which also generated UNREG15V, REG12V.
So look at page 39 to see if the REG12V on CN6150 also drops down.
I think we have problem there for the VCC_12V if it drops down to 6V.

[6ot4hr]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

It's 2AM at my place, will give it a rest till tommorow. One interesting thing i didn't notice on main board, optical audio doesn't light up and usb has no +5V, but all IC's on the main board have VCC present... That bravia is just one sad puppy

[6ot4hr]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

Morning update:
Managed to make TV led blink error codes. Now the set PSU turns on and after some time turns on giving 8 red blinks... (Audio error), any thoughts on that?

Doesnt react to CH UP + PWR button reset methode

[budm]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

Morning update:
Managed to make TV led blink error codes. Now the set PSU turns on and after some time turns on giving 8 red blinks... (Audio error), any thoughts on that?

Doesnt react to CH UP + PWR button reset methode

How did you do that? That error is probably due to DC offset detection at the output of the audio power amplifiers.

[6ot4hr]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

How did you do that? That error is probably due to DC offset detection at the output of the audio power amplifiers.

Left the TV unplugged over the night and re-plugged all of the connectors on the main board... Still haven't figured it out. Problem now is it still doesn't react to "reset procedure"... Any ideas where to look next?

[budm]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

I do not know, but at this point, it indicates problem on the main board.

[6ot4hr]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

Found another Bravia tv at a friends place, we will try parts swapping and hopefully not to kill the okay one in the mean time

[6ot4hr]

Re: Sony bravia Psu (A-1660-720-B) schematic needed

Found another Bravia tv at a friends place, we will try parts swapping and hopefully not to kill the okay one in the mean time

Final thought:

Exchanged motherboards and it seem to solve the problem, screen turns white (backlight is working ok) but the T-con panel connectors aren't the same on both TVs so it is impossible to test the panel.

Thanks all for the diagnosis and help, especially you Budm! Cheers!