Sony KDL-40EX40B - No power

[budm]

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.

Ah missing information about the storm.
Lets try this, disconnect everything from the power supply board except the power cord, then check and see if the 12V will be present or not when AC is applied to the power supply board.
What also bothers me is that the POWER_on signal is not present from the main board and no error code either so you may also have main board problem too.

[chris1434]

Re: Sony KDL-40EX40B - No power

I had removed the board so will put it back and let you know. I have to run some errands but will do it when I get back. Being on the west coast, you probably haven't started your day.

[chris1434]

Re: Sony KDL-40EX40B - No power

An interesting turn of events. I put the power board back on the tv and tested without anything attached (except for the power from the wall). I get 3.29 on the STBY and ACOFFDET. I don't get anything on the other pins. However, after that test, I decided to hook everything back up to see if would get the red light / green light sequence. I did but then the red light went out and started flashing. I got 2 flashes which I believe means the power board. I would think that also is a little bit of a vote of confidence for the main board at least working partially.

Assuming the 2 flashes are correct and there is an issue with the power board, are they any additional checks I can do to hopefully identify the problem component(s)? Also, are there any tests to determine if the main board might actually be okay?

[budm]

Re: Sony KDL-40EX40B - No power

How about the 12V? is it present when you power up the power supply board by itself?

[chris1434]

Re: Sony KDL-40EX40B - No power

I was reading another one of your posts and saw this:

Check the DCV between the two legs of the main filter cap when TV is turned on to see if you do have 380 ~ 400VDC PFC Boosted Voltage or not.
If not then you need to find out if the PFC IC has the switched VCC for it to run or not.

I plugged in the power cable and checked the voltage and also jumped from STBY to POWER ON. I did not get boosted voltage so I thought I should do the same test you wrote above. I believe the IC I need to test is on the back of the board and labeled IC6301. Pin 22 is VCC but I am not sure how to test it.

Do you agree that this is a test I should run and if so, how do I check it?

[budm]

Re: Sony KDL-40EX40B - No power

I was reading another one of your posts and saw this:

Check the DCV between the two legs of the main filter cap when TV is turned on to see if you do have 380 ~ 400VDC PFC Boosted Voltage or not.
If not then you need to find out if the PFC IC has the switched VCC for it to run or not.

I plugged in the power cable and checked the voltage and also jumped from STBY to POWER ON. I did not get boosted voltage so I thought I should do the same test you wrote above. I believe the IC I need to test is on the back of the board and labeled IC6301. Pin 22 is VCC but I am not sure how to test it.

Do you agree that this is a test I should run and if so, how do I check it?

Ooops, you did perform the jump test, I will have to look at the schematic first to give you the test points.
But is the 12V present or not?

[chris1434]

Re: Sony KDL-40EX40B - No power

Sorry Pin 20 is VCC. Typo.

[budm]

Re: Sony KDL-40EX40B - No power

OK, to find out if switched VCC for the IC6301 is present or not is to check the DCV between the two legs of cap C6117.

[chris1434]

Re: Sony KDL-40EX40B - No power

So, remove the board and bench test it? Plug in power cord and jump STBY to POWER ON?

[chris1434]

Re: Sony KDL-40EX40B - No power

12.39V on C6117. Main cap is at 160V.

[budm]

Re: Sony KDL-40EX40B - No power

So, remove the board and bench test it? Plug in power cord and jump STBY to POWER ON?

Yes, just be real careful since you are working in the HOT DEADLY SIDE of the circuit, do not touch any thing with your hands or body.

[budm]

Re: Sony KDL-40EX40B - No power

12.39V on C6117. Main cap is at 160V.

Need to look up the spec sheet of that IC to find out the minimum VCC it needs to operate.

[chris1434]

Re: Sony KDL-40EX40B - No power

I believe this is it.

[budm]

Re: Sony KDL-40EX40B - No power

Turn on Voltage level is 11V (spec sheet page 10), so the VCC Voltage is fine since you have 12V.
With jumper still in place, please check the Voltage at pin 2 (Mode), you can use the negative leg of C6117 for ground.

[chris1434]

Re: Sony KDL-40EX40B - No power

It's hard to tell which one C6117 is from the back. Is there another place I can use for ground?

[chris1434]

Re: Sony KDL-40EX40B - No power

0.097v

[budm]

Re: Sony KDL-40EX40B - No power

0.097v

That is correct, it is supposed to be like that when POWER_ON is present.

Unplugged the power to the power supply board and let it sits for 10 minutes, leave jumper in place.Keep the black probe on Ground pin of the cold of the connector of the power supply that goes to the main board, leave the red probe on the 12V pin, then apply power to the board and see if the Voltage on the 12V pin even jumps up at all or not. We are trying to see if there is any activity at all.

[chris1434]

Re: Sony KDL-40EX40B - No power

Are you talking about the connector in the attached picture? CN6401? If so, can I use either REG12V and either REG12V GND?

[chris1434]

Re: Sony KDL-40EX40B - No power

If my post above is what you asked me to do, the answer is the display did not change. With the jumper in place, I put the black probe into the 6th pin from the bottom (REG12V GND) and red into the 7th pin from the top (REG12V). I then plugged in the power cord but the display did not change. No indication of any kind.

[budm]

Re: Sony KDL-40EX40B - No power

If my post above is what you asked me to do, the answer is the display did not change. With the jumper in place, I put the black probe into the 6th pin from the bottom (REG12V GND) and red into the 7th pin from the top (REG12V). I then plugged in the power cord but the display did not change. No indication of any kind.

That means that IC is not driving the MOSFETs to produce the needed 12V, so need to look deeper to see if it is bad IC or something is locking out the IC.