Sony KDL-40bx421

[pop70458]

The tv has no standby light and will not power on.

The voltages i get are.

1.stby3.3v--------------3.3v
2.ac 0ff det-------------0v
3.power on-------------0v
4.AU_12V--------------0V
5.AU_12VGND
6.REG_12VGND
7.REG_12VGND
8.REG12V--------------0V
9.REG12V--------------0V
10.BL_ERR-------------0V
11.BL_ON--------------0V
12.DIMMER------------0V
13.ACT_STBY---------0V
14.TCON VCC_12V---0V
15.TCON_ON---------0V

[pop70458]

Re: Sony KDL-40bx421

I think this is the power supply schematic.

[budm]

Re: Sony KDL-40bx421

'2.ac 0ff det-------------0v' That should be around 3VDC for normal condition. I do expect that the stby LED should be on because you do have stby Voltage, it should also show blinking error codes..
BTW, the small yellow fuse ps6402 is good?
Service manuals
http://elektrotanya.com/?q=showresul...oria=&kat2=all

[pop70458]

Re: Sony KDL-40bx421

The small yellow fuse is good but i don't have any blinking codes.

[dick_barton]

Re: Sony KDL-40bx421

+1
Check the voltages at AC_DETIN and AC_DETOUT of the CXA3810 (IC6301)

[pop70458]

Re: Sony KDL-40bx421

What do i use for the ground to check the CXA3810?

[dick_barton]

Re: Sony KDL-40bx421

I don't have the manual for the set but pin 18 of that chip is a ground connection.

[budm]

Re: Sony KDL-40bx421

Service manuals.
The 'sony_kdl-32bx320_321_420_421_40-46bx420_421_chassis_az2-uk.pdf' has power supply diagram.

[pop70458]

Re: Sony KDL-40bx421

I get these readings.

AC_DETIN-------0.02v
AC_DETOUT-----0.10v

[budm]

Re: Sony KDL-40bx421

AC_DET input is AC as explained in the spec sheet of the IC CXA3810 page 23~31.
G14 diagram.

[budm]

Re: Sony KDL-40bx421

BTW, you need to check the value of those resistors network of the ACINDET, R6301~6305 as shown the diagram of the PS.

[pop70458]

Re: Sony KDL-40bx421

I'm not the greatest with schematics but these are the reading i got. i had my meter set on 2000k for r6301-r6304.
R6301--320
r6302---320
r6302---320
r6304---320

I set my meter on 200k for r6305.
r6305---27

[budm]

Re: Sony KDL-40bx421

I'm not the greatest with schematics but these are the reading i got. i had my meter set on 2000k for r6301-r6304.
R6301--320
r6302---320
r6302---320
r6304---320

I set my meter on 200k for r6305.
r6305---27

That is fine, now you need to read ACV at the ACINDET pin of the IC.

[pop70458]

Re: Sony KDL-40bx421

With the meter set to 200 vac i get 0.00v.

[budm]

Re: Sony KDL-40bx421

With the meter set to 200 vac i get 0.00v.

Is that with the black lead of the meter probe on GND pin of the IC?
I expect something but not 0V.

[pop70458]

Re: Sony KDL-40bx421

Yes on pin #18.

[budm]

Re: Sony KDL-40bx421

Take the ACV reading of A, B, C, D against GND. You can run the board by itself to check the Voltages.

[pop70458]

Re: Sony KDL-40bx421

What to use for ground?

[budm]

Re: Sony KDL-40bx421

What to use for ground?

Pin 18 of the IC? What did you use then when it is showing 0 VAC?
As you can see, the whole bottom horizon line is GND as marked and a lot of devices are connected to that GND line.

[pop70458]

Re: Sony KDL-40bx421

I used pin 18 for the ground when i got 0 vac. I get these readings with the black probe on pin 18 and meter set to 200 VAC.

R6301 51.4
R6302 30.9
R6303 19.2
R6304 10.2