Sony XBR75X850C no picture backlights on

[Davi.p]

Re: Sony XBR75X850C no picture backlights on

There can be some secrets as i have seen on my Sony, you know, but it's possible also a failure in the ICs, it's very uncommon that searching for the panel model i don't find anything, searched also S650qf59 OR S550qf59 OR S500qf59 OR S470qf59 but nothing, so i re-ask you is the model number exact? With no datasheets is not possible to proceed i think, as all tcon i have seen started by 12v in, not by a command from mainboard.

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

Ok try this. Panel model 14Y_75UDMB3SFR4LV0.0 At least that's what's on one of the source driver boards.

That probably doesn't do any good I can't find it in a Google search

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

I wonder if this system is like the failing ISL9860 other tcons have

[Davi.p]

Re: Sony XBR75X850C no picture backlights on

The right part number is usually placed on a white sticker on the panel metal chassis, but unfortunately Sony seems to remove theese one to make the panel like Sony brand but i recongnize it from tcon number and connectors it's much probably Samsung panel. I have an idea, if you have an eeprom programmer (you must have) you can try to read the 2 (or four? Need a good TCON picture!) eeproms near the processor, using the tcon pw.supply and connecting to the programmer only SDA,SCL tespoints near them, inside one of them i think there is the correct model number like i have found in mine..

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

Yes this is a Samsung LCD panel.

Tcon Part number LJ94-32255G
That part number is definitely Samsung
It's a good idea about reading in the eeprom.

I tried feeding 16 from another tcon. Did not get good results most likely because of cross talk.

But check this out. Similar tcon, same processor IC. For a Samsung un75ju641df uses same everything.

[Davi.p]

Re: Sony XBR75X850C no picture backlights on

uses same everything.

same what? I don't see ic markings...

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

Main processor.

Samsung model.

Mine is also VTU10A1

[Davi.p]

Re: Sony XBR75X850C no picture backlights on

But it don't helps you! :-J

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

Here are better hi res photos of my board. Ignore CG9, I took it off and resoldered it in testing, but I didn't do a good job keeping it straight.

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

But it don't helps you! :-J

It may help because I have one in my possession putting out all the proper voltages and it uses the same regulators as the Sony board.

LVDS inputs are a different clamp style But outputs are identical to my panel

[Davi.p]

Re: Sony XBR75X850C no picture backlights on

It may help because I have one in my possession

ah ok...

[Davi.p]

Re: Sony XBR75X850C no picture backlights on

First of all i wanna make sure you are checking the right places, VON it is measured on the cathode of DG51 (left upper area, 2nd photo), VOFF probably on the CG52-3 or CG57-8 (same area), VON and VOFF are repeated on the last photo (same chip type), VON on cathode of DG1, VOFF on CG7-8. AVDD is formed by the power components in parallel (A-B) QS1-2, LSA1-B1, DSA1-B1, CSA7-B7, with the switches ICA1-B1 that feeds VIN12v to those DC-DC boost. AVDD is measured on CSA7-B7. You have to test those points in volt, and if no volt check all the diodes,mosfets,bjts. IF the protection is shutting down at powerup, if you have followed my big Sony journey, you can search for a timing cap, much probably CS36 that is the smaller, it has to be small.. you can cross your fingers and short it for 1-2secs or more at powerup and see if something warms up too much or the tensions come out... good luck..

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

Davi.p you rock! Thank you! Ill report my findings

[Davi.p]

Re: Sony XBR75X850C no picture backlights on

On CHS1-2 and CSH3-4 you have to find probably 3,3v

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

All those test points are dead except CS36 is the 5v in. I took a gamble and tried shorting that cap anyway. Nothing does far in for some reason this doesn't even have an effect on the bucking regulators for the 1.1v ICD2, This area seems to be unaffected by anything that I do. of course this runs the core voltage for the CPU

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

ChS1 and 2 are bothh dead also. They do come alive when I inject 16v into HVDD But this is backfeeding and not really affecting ICD1 or ICD3.

IcD4 doesn't change and there's no voltage around it except for the 5v in

[Davi.p]

Re: Sony XBR75X850C no picture backlights on

have you got a scope with recording function or a meter with max fn? You can test if there are spikes that tells you the tensions are trying to come up

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

I have an oscilloscope however I still need to get my new probes somehow I lost my old probe. It's just a BK precision one. Not too great but it does the job

[will62]

Re: Sony XBR75X850C no picture backlights on

Hey freak, do you have this already?

https://www.manualslib.com/download/...r-55x850c.html

[freakaftr8]

Re: Sony XBR75X850C no picture backlights on

Wow no I didn't! Thank you!

Interesting read here. Wonder how the mainboard mutes the picture when firmware needs upgrade to new tcon/panel?