Sony Bravia KDL-46EX640 no power

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

@ budm: so the mainboard is now a suspect? what do you think?

[budm]

Re: Sony Bravia KDL-46EX640 no power

At the white connectors:

T-Con ON = 0 V
T-Con-Vcc-12 = 0 V
NC = N/A
Dimmer = 0 V
BL-ON = 0 V
BL-ERR = 3.310 V
REG-12V = 12.58 V
REG-12V = 12.58 V
REG-12V-GND = 0 V
REG-12V-GND = 0 V
Audio-12V-GND = 0 V
POWER ON = 3.307 V
ACC OFF-DET = 2.933 V
STBY 3.3V = 3.327 V

Any suspects?

Right now the PS_ON is stuck high.
The main board is not sending out the T-CON on signal to turn on the 12V supply to the T-CON, the main board is also not sending the BL_ON and the Dimming control signals either.

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

Now Im shifting my focus to the motherboard after installing the newly bought power supply board and still a deadset.

No LED lights you can see in front. Pushed the power button at the side, still no joy.

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

98% of the zero power issues I have encountered always seem to lead to a bad power supply board. Even after testing components that seemed ok. Just had a toshiba this weekend with the same issue your having. No standby, no front light, wouldn't respond to remote or side buttons. Just dead!! With meter I could tell the ps board was getting power but that's as far as it was going. No output. Ceramic fuse was fine as well. In most cases this will be a bad ps board. You'll just have to decide if you want to hunt down components or just replace the supply board itself. Rare occasions it can be the main board, but from experience, a bad main will still allow a standby light.

Here was the toshiba I was referring to. Replaced ps, and it lives!! Best of luck

https://www.youtube.com/watch?v=Bk9a...ature=youtu.be

Bought a power supply board from shopjimmy. Got hold of it an hour ago. But unfortunately, still a deadset after installing the new power supply board.

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

Maybe one side goes to ground.

Possible since looking back at the white connector designation it directly connects to the following pins:

REG-12V-GND
REG-12V-GND
Audio-12V-GND

But, the other side of the resistor is directly connected to the positive side of 1500uF/16V electrolytic capacitor which I also checked the capacitance and ESR values and are OK.

[tibimakai]

Re: Sony Bravia KDL-46EX640 no power

Maybe one side goes to ground.

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

Also, if I voltage check R6419 the one side is 0V but on the other side is 12.5V. You can see the component on the first pic posted above.

I pull out this resistor labeled as 471J 1W and here is the measured resistance 468 ohms.

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

At the white connectors:

T-Con ON = 0 V
T-Con-Vcc-12 = 0 V
NC = N/A
Dimmer = 0 V
BL-ON = 0 V
BL-ERR = 3.310 V
REG-12V = 12.58 V
REG-12V = 12.58 V
REG-12V-GND = 0 V
REG-12V-GND = 0 V
Audio-12V-GND = 0 V
POWER ON = 3.307 V
ACC OFF-DET = 2.933 V
STBY 3.3V = 3.327 V

Any suspects?

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

I have done some simple voltage tests. Please see attached pics.

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

I'm planning to replace MIP2H2, C6308, C6311, C6310, C6524. Any suggestions?

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

By the way what is this component labeled as FB6301 at the power supply board?

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

Switch should be fine. Use ohm meter (set unplugged) to test switch. Your getting 390 vdc on big filter cap. Your signal from main board to p.s. is telling set to turn on. Unplug the main board and plug it in wall if it still turns on there USA PS issue too

I use the wall outlet. same result.

[Ltank]

Re: Sony Bravia KDL-46EX640 no power

Switch should be fine. Use ohm meter (set unplugged) to test switch. Your getting 390 vdc on big filter cap. Your signal from main board to p.s. is telling set to turn on. Unplug the main board and plug it in wall if it still turns on there USA PS issue too

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

The Tv PS turns on as soon as the set is plugged in and the PS turns on? Can it still be turned off and back on? The MB gives the PS_On all the time? Normally if there is no standby voltage the set will not turn on at all. Strange

When I plug the unit to the wall outlet, i didnt see any RED LED Standby Indicator at the front panel. But when I trace the voltage starting the AC side, voltage is present, DC across the big filter capacitor is also present and in normal value.

BUT, even if I press the POWER SWITCH located at the side of the unit, the DC voltage across the big filter capacitor remains the same. No changes at all. Does this mean a bad power switch?

[Ltank]

Re: Sony Bravia KDL-46EX640 no power

The Tv PS turns on as soon as the set is plugged in and the PS turns on? Can it still be turned off and back on? The MB gives the PS_On all the time? Normally if there is no standby voltage the set will not turn on at all. Strange

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

D6303: Anode = 374.4 Vdc / Cathode = 420Vdc
D6308 = 14.41 Vdc
D6307 = 13.98 Vdc

Im wondering if the ESR values stated are beyond their normal values. Do I have to replace those caps? Any inputs?

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

These components are also taken out and measured:

C6308: 4.7uF/50V (measured = 4.8uF / ESR = 3.3 ohms)
R6301: 10 Ohms (measured: 10.3 Ohms)
R6302: 100KOhms (measured: 99.1 KOhms)
C6311: 2.2uF / 50V (measured: 2.38uF / ESR = 5.8 Ohms)
C6310: 100 uF/50V (measured: 110.9 uF / ESR = 0.65 Ohm)
C6524: 10uF/50V (measured: 10.5uF / ESR: 2.3 Ohms)

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

Other voltage infos:

D6303: Anode side: 374.4 Vdc and Cathode side: 420 Vdc
D6308: 14.41 Vdc
D6307: 13.98 Vdc

IC6301 (MIP2H2):

Pin 1: 5.74 Vdc
Pin 2: 1.632 Vdc
Pin 3: 0V
Pin 4: 14.41 Vdc
Pin 5: 374.5 Vdc
Pin 6: - - -
Pin 7: 0V
Pin 8: 0V

Any ideas?

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

What do you get at D6201? That should be the diode after the standby transformer. Use the TV for ground when measuring.
Monday I should get the part.

D6201 voltage is 3.327Vdc.

[bullwinkle]

Re: Sony Bravia KDL-46EX640 no power

If that is the case, then the main board is sending out the PS_ON to turn on the PFC voltage booster. Turn the TV power switch to off, then the voltage on the cap should drop down to around 160~170VDC. Your meter is good, right?

Turned the switch to OFF but still the voltage present across the big filter capacitor is 393.4Vdc.