Sony KDL-40W600B blank backlit screen with sound

[triplefour]

tv powers on/off ok, and i can hear sound via laptop hooked to hdmi port
but i get no picture.

of course i suspect something is wrong with the tcon (built into the mainboard), or worse, the panel itself.

i get 12v at the fuse next to the LVDS cable on the panel side
and i get ranging voltages on those test points right below the LVDS cable as high as 1.6v and as low as 0.3v

[dick_barton]

Re: Sony KDL-40W600B blank backlit screen with sound

Are you sure it's no picture or is it no backlight. Can you see a picture if you shine a very bright light on the screen and look carefully?

[diif]

Re: Sony KDL-40W600B blank backlit screen with sound

Have you measured the voltage at VIN_12V in photo 4 ?

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

here are all voltages in that area
thank you for any brain power you have to lend me

and dick_barton, yes i am sure the backlights are on. i can see them. and no picture. flashlight is not needed.

[budm]

Re: Sony KDL-40W600B blank backlit screen with sound

https://www.badcaps.net/forum/attach...8&d=1522555588
You will have to trace the V1N_12V pad which is connected to the bottom side of the board through VIAS, and see where it goes and if you are getting 12V on the bottom side of the board or not.
There will be switching power supplies on that integrated T-CON board.

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

it took some work getting to the underside of the board, but there are no components there. theyre all on the top side. last image has some new voltage measurements i took now that i can get at more of it.
i see a lot of 0v with a sprinkling of 12.5 and 5v here and there...the pins on ICD1 are too close together to get my probe on them without bridging pins, except for the ones on the edges. so i tested all those. they were 0 except for the 12.5 and 5v i noted in the picture.
sorry for taking so long to look at this tv again, but you know how it is. life!

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

any ideas? im stuck

[Andrew F. Ali]

Re: Sony KDL-40W600B blank backlit screen with sound

In photo No. 1 to the right see if you have 12Vdc on both sides of the white fuse with the gold ends.

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

the last image has the voltages i measured labeled on it. 12v on both sides of the fuse. first thing i checked.

[Andrew F. Ali]

Re: Sony KDL-40W600B blank backlit screen with sound

https://www.badcaps.net/forum/attach...8&d=1522555588
You will have to trace the V1N_12V pad which is connected to the bottom side of the board through VIAS, and see where it goes and if you are getting 12V on the bottom side of the board or not.
There will be switching power supplies on that integrated T-CON board.

As stated there would be Switching Power Supplies on the T-CON Bd. that would take the Vin: 12V and convert that to Vdd: 3.3V, Vda: 14 to 20V, Vgh: 20 to 30V and Vgl: -5 to -7V. Look for and measure these 'top 5' voltages on the T-CON Bd. to produce a picture on the screen.

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

Look for and measure these 'top 5' voltages

If you don't tell him where to test.... check across bigger capacitors..

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

im getting confused... are we talking about voltages on the tcon, or the "panel board" (is that what its called?)
im thinking tcon is at least mostly functioning because it sends 12v to the panel board. am i wrong to assume this?

[budm]

Re: Sony KDL-40W600B blank backlit screen with sound

That long board attached to the LCD panel is the integrated T-CON/tab bonding board, it is not typical separated T-CON in most TV, it is money saving panel with non-replaceable T-CON.

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

thank you for the clarification... so the tcon can be on this thin "panel board" that isnt replaceable??...what a bunch of cheap bastards!

its not convenient, but its still possible to troubleshoot and replace components on this board, so i'd like to give it a try

but i'm still lost as to what to check next and how to determine a component on this board to replace to get the picture showing!

you have seen the voltage measurements i made in the last picture of post #6, yes?

thank you

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

A.ALi has told you which tensions to find, i have told you where to test them (very approximately) so what you waiting for?

[nomoresonys]

Re: Sony KDL-40W600B blank backlit screen with sound

Probably waiting for clear instructions.

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

Are almost clear, also for a children, test in volt every big capacitor on tcon.

[Andrew F. Ali]

Re: Sony KDL-40W600B blank backlit screen with sound

If you look carefully at the Integrated T-CON/Driver Bds. The voltage points I asked you to measure are there but under their other names, so it may have been confusing to you. The points to measure are little gold looking dots. The expected voltage and other names of the same test points are in brackets, so here goes:
1. Vin: 12V (we confirmed as present)
2. Vdd (Vlogic, Vddd): 3.3V
3. Vda (Vs, Vsource, Vdda Avdd): 14V to 20V
4. Vgh (Vgon, Von, Vddg): 20V to 30V
5. Vgl (Vgoff, Voff, Veeg): -5V to -7V

[budm]

Re: Sony KDL-40W600B blank backlit screen with sound

Also get the spec sheet of the IC's so you can check the VCC pin, that is what I do when I do not have schematic of the board, the spec sheet will also have application circuits showing how the IC is hooked up and most companies will used that as the design for their boards.

[Andrew F. Ali]

Re: Sony KDL-40W600B blank backlit screen with sound

Also get the spec sheet of the IC's so you can check the VCC pin, that is what I do when I do not have schematic of the board, the spec sheet will also have application circuits showing how the IC is hooked up and most companies will used that as the design for their boards.

Good advice.