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

[6ot4hr]

Hello all, i have Sony bravia LCD tv with faulty power supply and i need schematic for it.
Exact model of power supply is A-1660-720-B.
Anyone has it?

Symptoms: Tv doesn't turn on, only green light comes up (no blinks or error codes). Screen is completely blank.

[budm]

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

What is the model of the TV?

[6ot4hr]

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

Hi budm,
model is: KDL-40W5800 AEP

[Diah]

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

after its LED goes green.. plug it out and in fast at wall socket and tell how many red Led blinking?

[budm]

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

Hi budm,
model is: KDL-40W5800 AEP

Service manual.

[6ot4hr]

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

Tried plugging it out and in fast, can't make it blink red... Only green led light comes on and stays on.

On Cn6701 (to the inverter board) i have voltages:

Vcc12V - only 6 volts
FB - 0 V
LD - 5V


CN5151 (to Tcon):

GND - GND
12V - 12 volts measured


CN5150 (to Main board):
12V - 11.9 volts measured
15V - 14.8 volts measured
STB3.3 - 3.2 volts measured
GND - GND

[Diah]

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

firmware issue etc main boards

[6ot4hr]

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

Quick question, I unpluged the inverter board (SSb400W12s01) from the PSU. It seems that FB is shorted directly to the GND, should that be so?

After unpluging it from the PSU, i get normal 12V VCC on the cn6701 on the PSU.

[budm]

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

What dcv do you have on ALL the pins (except GND pins) of the power supply connectors:
CN6154
CN6151
CN6150

[Diah]

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

Quick question, I unpluged the inverter board (SSb400W12s01) from the PSU. It seems that FB i shorted directly to the GND, should that be so?

After unpluging it from the PSU, i get normal 12V VCC on the cn6701 on the PSU.

you got it why no red error led blinking

[6ot4hr]

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

CN6154
NC - 2.11V
Dimm - 0V
BacklON - 1.9V
GND - 0V
bal err - 0V

CN6151:
GND - 0V
12V - 11.9

CN6150
12V - 11.9
15V - 14.8
STB3.3 - 3.2
GND - 0

[budm]

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

FB pins (CN6701 pin 2, 3) are for the Lamp current sensing signal pins, it will be in mVAC when Lamps are on.
LD (Lamp detect) normal should be around 10~11VDC, it goes LOW if there is error.
Are you sure you did not see the backlights even come on for seconds? I also expect some kind of bliinking LED error code.
Do you also know the history of this TV? Anyone else try to fix this TV before? Firmware updated?

[6ot4hr]

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

FB pins (CN6701 pin 2, 3) are for the Lamp current sensing signal pins, it will be in mVAC when Lamps are on.
LD (Lamp detect) normal should be around 10~11VDC, it goes LOW if there is error.
Are you sure you did not see the backlights even come on for seconds? I also expect some kind of bliinking LED error code.
Do you also know the history of this TV? Anyone else try to fix this TV before? Firmware updated?

I believe no firmware updates were being done on it, TV is from a non tech friend.
No backlight, even a bit, i tried flashlighting the screen (pressing ch+ ch- home) in order to make it show something but no luck, no picture could be seen.

FB pin is shorted to the GND, will try to diagnose why it shorted and what died on it.

Btw, should i buy new inverter board since i cant get any blink error codes. Could the main board be dead too?

[budm]

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

I think you have main board problem due to the fact that it did not show any error codes, if you have the problem with the power supply-inverter board combo, you will get error lights. The big long board where the lamps are attached to is not inverter board, it is the Balancer board.

"FB pin is shorted to the GND, will try to diagnose why it shorted and what died on it."
if you look at the diagram, you will see a bunch of low value current sensing resistors connected in parallel, that is why you are seeing very low resistance between FB and GND, it is normal.

[6ot4hr]

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

Ah sorry for mixing inv and balancer boards and thank you all for your quick replies. Especially budm, thank you sir very much. (a lot of knowledge in you sir)

Anyhow, U1 2903 PLRA (ic) has 3 of its legs shorted to the ground.




I will continue fixing it tommorow when the sun comes up.

[budm]

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

U1 on which board?

[6ot4hr]

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

U1 on which board?

Balancer board

[budm]

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.

[budm]

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.

[budm]

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

SONY backlights system concept.