Sony KDL-40EX40B - No power

[chris1434]

I watched several troubleshooting videos and read many threads on this forum but not sure which board is the issue. Here is what happened.

Last night

Turned on the tv and got the green power light but no audio or video. Shined a light on the screen and didn't see a picture. All indication is the tv is dead except for the green light.

Turn TV off. Red standby light comes on. Press power again. Green light comes on but nothng else. Repeat this a few times with same result.

Unplug the tv and wait a few minutes and plug it back in. Same result.

After doing this a few times, suddenly the red light nor green light would come on.

Never was able to get the red or green light to come on. Gave up for the night.

Today

Plugged the tv in. Suddenly I could get the red light and then green light by pressing the power button but still nothing else.

If I left it with the green light on, the green light will turn off by itself after a few seconds.

If I leave it with the red light on, it appears to stay on (I left it for about 2 minutes and it was still on). Again, if I press the power button again to get the green light, the green light will go off after 10 seconds or so.

After doing this several times, neither light would come on. I have found that if I leave it unplugged for a while and plug it back in, SOMETIMES I get the red light green light sequence but generally I get nothing.

Tests I have done:

Power Board

CN6401
3.3 volts present at STBY3.3V
3.3 volts also present at ACCOFFDET
POWER ON pin - No voltage
No voltage on 12V pins

I put a jumper from STBY3.3V to POWER ON but still do not get any voltage on 12V pins.

Throughout my testing I have gotten no indication that the TV has attempted to come on. The best I can do is the red light green light sequence on occasion. If I jumper from STBY3.3V to POWER ON, I can almost always get the red light, green light to work with the power button.

All suggestions much appreciated.

[budm]

Re: Sony KDL-40EX40B - No power

I watched several troubleshooting videos and read many threads on this forum but not sure which board is the issue. Here is what happened.

Last night

Turned on the tv and got the green power light but no audio or video. Shined a light on the screen and didn't see a picture. All indication is the tv is dead except for the green light.

Turn TV off. Red standby light comes on. Press power again. Green light comes on but nothng else. Repeat this a few times with same result.

Unplug the tv and wait a few minutes and plug it back in. Same result.

After doing this a few times, suddenly the red light nor green light would come on.

Never was able to get the red or green light to come on. Gave up for the night.

Today

Plugged the tv in. Suddenly I could get the red light and then green light by pressing the power button but still nothing else.

If I left it with the green light on, the green light will turn off by itself after a few seconds.

If I leave it with the red light on, it appears to stay on (I left it for about 2 minutes and it was still on). Again, if I press the power button again to get the green light, the green light will go off after 10 seconds or so.

After doing this several times, neither light would come on. I have found that if I leave it unplugged for a while and plug it back in, SOMETIMES I get the red light green light sequence but generally I get nothing.

Tests I have done:

Power Board

CN6401
3.3 volts present at STBY3.3V
3.3 volts also present at ACCOFFDET
POWER ON pin - No voltage
No voltage on 12V pins

I put a jumper from STBY3.3V to POWER ON but still do not get any voltage on 12V pins.

Throughout my testing I have gotten no indication that the TV has attempted to come on. The best I can do is the red light green light sequence on occasion. If I jumper from STBY3.3V to POWER ON, I can almost always get the red light, green light to work with the power button.

All suggestions much appreciated.

Did you put a jumper from STBY3.3V to POWER ON when the connector between power supply and main board is still connected together? If you did you can damage the Main board.
When perform force on you MUST disconnect the cable between power supply and Main board first, and always use resistor for force on.

[chris1434]

Re: Sony KDL-40EX40B - No power

Sorry for leaving out that detail. It was disconnected. I had read where you could do that and on some tv's if the power supply was good, it would light up the backlight.

[budm]

Re: Sony KDL-40EX40B - No power

Power_on (PS-ON) is receiving pin is for getting the control from main board to turn on the switched power supply section.

The BL-ON is the receiving pin for getting the control from the main board to turn on Backlights circuit.

Dim/PWM-DIM is the receiving pin for getting the control form main board to set the backlghts level.

We need to see the pictures of the whole backside of the TV showing all the boards, also good clear straight shots pictures of the whole top and bottom side of the power supply board, the pictures must be clear enough to read the texts on the board.

[chris1434]

Re: Sony KDL-40EX40B - No power

Hopefully these are good enough.

[budm]

Re: Sony KDL-40EX40B - No power

Can you please take closed-up pictures around the connectors so i can easily see the pin names?

[chris1434]

Re: Sony KDL-40EX40B - No power

Here you go. Please let me know if you need anything else. Thanks in advance.

[budm]

Re: Sony KDL-40EX40B - No power

BTW, you are not seeing blink code?
According to training manual, the 12V is not switched 12V.
Did you check the fuses, PS6401, PS6402?
See attached training manual and power supply schematic APS-255..
Please study them.

[chris1434]

Re: Sony KDL-40EX40B - No power

No blink code as of yet but the problem has evolved a bit with the lights. I was consistently getting red standby and then green when power button was pressed. Then those wouldn't come on at all. Now they will come on every now and then but not consistently.

PS6401 and ps6402 test good. As for 12V, are you saying 12V should be present anytime the board is plugged in?

[chris1434]

Re: Sony KDL-40EX40B - No power

I have only tested at the CN6401 connector but have not gotten 12v at any time. Is there somewhere else I should test for voltage other than STBY, ACOFFDET AND POWER ON?

[budm]

Re: Sony KDL-40EX40B - No power

No blink code as of yet but the problem has evolved a bit with the lights. I was consistently getting red standby and then green when power button was pressed. Then those wouldn't come on at all. Now they will come on every now and then but not consistently.

PS6401 and ps6402 test good. As for 12V, are you saying 12V should be present anytime the board is plugged in?

Please look at my post #8.

[chris1434]

Re: Sony KDL-40EX40B - No power

I read those yesterday but don't have the level of understanding to know how to confirm what is bad. It seems like the power board but I was hoping to find the actual component(s) that are bad.

[budm]

Re: Sony KDL-40EX40B - No power

I read those yesterday but don't have the level of understanding to know how to confirm what is bad. It seems like the power board but I was hoping to find the actual component(s) that are bad.

The exact same training manual?

You do know how to read the schematic, correct?

[chris1434]

Re: Sony KDL-40EX40B - No power

I think so. I attached the 2 I read.

[chris1434]

Re: Sony KDL-40EX40B - No power

No, I do not know how to read a schematic.

[budm]

Re: Sony KDL-40EX40B - No power

Check 0.1 Ohm fusible resistor R6342.

[budm]

Re: Sony KDL-40EX40B - No power

I think so. I attached the 2 I read.

Chassis AZ1BD is for the model with Bluray player (your TV).
Chassis AZ1-L is for the same model but without Bluray player.

It will be hard if you do not know how to read schematic.

How about tools? Do you have tools to do surface mount component repair?

[chris1434]

Re: Sony KDL-40EX40B - No power

I get .2 and then it changes to .1

[chris1434]

Re: Sony KDL-40EX40B - No power

As for repair, I have 2 options. If it's simple, I can do it. If it's complex, I have a buddy who could do it. However, if I can get a high level of confidence it is actually the power board, I would likely just replace it. Primary goal is to avoid replacing the power board only to find out it's the BAL board. That's why I was thinking there might be other locations to check voltage to at least confirm it's the power board.

[chris1434]

Re: Sony KDL-40EX40B - No power

I am in South Georgia where we have been having almost daily thunderstorms. The day this died, we had a bad storm but I wasn't home to know whether there was a lot of lightning at our house. I am not big on coincidences so I am assuming that is what took it out. But, it's 10 years old so it could have met it's timely death.