Sony KDL-40V5500: Sound and backlight ok, no picture

[yoritomo]

Sony KDL-40LV5500
Power supply: A1660-720B
Mainboard : A1663-964B
T-Con: NP_HAC2LV1.1


Hello all, this TV has a normal sound and the backlight is working normally, but the screen is still blank black screen. Firstly i checked the T-Con Power which is good with 11.98V then i tested the T-Con self test method, disconnecting LVDS i connected 12V to the power pin and 3.3V to de pin 44 of the LVDS , at that time i could see plenty of vertical color lines on a black background same as a dead LCD panel, but not the expected color bars.
When checking the T-Con board i can see around the chip ISL24007IRZ a rainbow spot all around as i could imagine as a serious overheat of this chip.

I measured all necessary test points as following :
VDD: 3.37v
VCC_1.8: 1.82v
VCC_3.3: 3.37v
AVDD: 0v
AVDD_I: 12.1V
VIN: 11.98V
VDD10_33: 3.37v
VDDC_18: 1.81v

A picture of the T-CON from the net.



Thanks a lot for your help.

[dskall]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

Doesn't look like anything is dragging voltages down. Wonder if AVDD should be 0v

[yoritomo]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

Usually what would be that value ? I was asking myself too.

[dskall]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

My notes say 14Vdc~20Vdc

[yoritomo]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

you could find the service manual for this t-con board ? Tomorrow i am going to check the small chip just beside the testpoint looks like it is a small
regulator

[budm]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

What is the P/N of the IC11? That IC looks to be for the AVDD supply.
Typical Voltages:
https://www.badcaps.net/forum/showthread.php?t=35301

[yoritomo]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

IC11 has a marking code "4438" , it is 6 pins and i could find 12V on pin 4, i could not identify this chip. Nothing matching in the Aswo database.

Edit: just now i made a mistake testing the T-Con and now , no more main 12V , i found a blown SMD 3.15A fuse on the main board, the replacement did not resolve it then look like i killed the MOS TPC8109, it is 12€ excluding VAT and 2 weeks delay :s, is it any cross references for this MOS ?

[dskall]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

Maybe at this point a new t-con would be cheaper

[yoritomo]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

the dead MOS is not in the T-con but on the main board .

[dskall]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

You can try this http://www.allxref.com/

[yoritomo]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

Thank you for this excellent link, how about IC11 marked 4438 ? what can it be ?

[dskall]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

Maybe a close up of board would help

[yoritomo]

Re: Sony KDL-40V5500: Sound and backlight ok, no picture

This image is centered on IC11 which looks like the regulator providing the AVDD voltage, looks like it is dead because i found 12V on pin 4 and nothing on the pin going to AVDD