Trying to Save - SONY BRAVIA KD-75X780F - No Picture BUT there’s sound

[nomoresonys]

I would just let it sit like that for a couple hours, it might be that people are quiting too early before everything is done updating, maybe.

[Diah]

Diah nomoresonys
I reformatted the drive (with RUFUS) and installed the file again (changing the name to upgrade_loader).
I plugged the thumb drive into the TV and tried to boot from disk but it didnt take.
I unplugged it. This time I pressed both the POWER and (-) when I plugged it back in and as soon as I did i saw a solid green status light.
I let go of both buttons and the light turned from green to pulsing white. The thumbdrive was constantly active as indicated by the drives built-in LED.
When I returned about 40 minutes later the status light is a solid dim white and the TV looks normal. It seems the firmware update is complete but there is still no picture.

this what i wrote before at post #131 - 137, so you are successful now with firmware and parts married.

now no picture you need to disconnect U ribbon at the panel buffer boards left and right .. you will have 3/4 picture...
75 size id there broken small vcc line on screen glass will make the hole screen blank.

[Davi.p]

Kybosh You posted wrong photos, i asked only the portion of sticker, the second one is unreadable..

[KYBOSH]

Kybosh You posted wrong photos, i asked only the portion of sticker, the second one is unreadable..

Apologies Davi!
I used an iphone 6 on my workbench to take that pic.
I knew it was going to be garbage!

[KYBOSH]

this what i wrote before at post #131 - 137, so you are successful now with firmware and parts married.

now no picture you need to disconnect U ribbon at the panel buffer boards left and right .. you will have 3/4 picture...
75 size id there broken small vcc line on screen glass will make the hole screen blank.

Yes, the TV has been sitting for several hours. Same solid white status light.
I believe it should have updated no problem.
I will remove U-cables tomorrow morning and report back.

If VCC line is the issue I maybe out of luck.
I have never even attempted such a repair as cutting these small traces.
I have watched it done (in amazement) on youtube but never dared to try it myself.
I wouldnt mind giving it a shot but only if properly guided by an expert who is patient with a new student.

[Davi.p]

.

[KYBOSH]

Tried the TV with Left and then Right U-cable off and still got no image.

The LCD display is active however bcos when you tap the screen you get flashes of white,

I guess i need to start considering cutting some traces....

[KYBOSH]

LEFT



RIGHT


Very Interesting Video!

As an aside... has anyone had any experience with a short killer device like the one he uses?


Edit to add:
Primer for reference

What is CKV1 CKV2 CKVB CKVB2 & Common Electrode of LCD

[nomoresonys]

Need to think before acting, the question is, are we sure that the panel is shorted??

[KYBOSH]

Need to think before acting, the question is, are we sure that the panel is shorted??

Agreed! The video explains how to check various components (capacitors, rectifiers, etc) BEFORE cutting lines.
But their example was a simpler TV set (with a conveniently placed PMIC). I am studying the video still.
Will look if there is a schematic for this TV somewhere online so easily check the appropriate component(s).

[KYBOSH]

Definitely out of my league on this TV when it comes to shorts.
I'll wait to hear back from you guys who have experience with this.

[nomoresonys]

Ok, so what was the vgl, vgh etc. readings on the tcon? When those correct voltages are missing it may very well be a sign of a panel short.

[lotas]

Check the resistance of each pin relative to GND.

[nomoresonys]

.

[KYBOSH]

Doing more reading I saw that the CKV lines short to their corresponding CKVB lines (CKV1 goes with CKVB1 and so on).
I figured I could go in and measure the resistance of the pair to see if I could at least get a clue about what might be happening.
This logic maybe completely wrong but I figured I'd see what I could see.

Conveniently the T-Con has a section of test points dedicated to the CKVs and CKVBs.



All the CKVs and CKVBs have ~12.0MΩ of resistance (11.95M-12.0M).

Just out of curiosity i started checking the CKVs against themselves (CKV1 to CKV2) and none of those were shorted either (roughly 3MΩ if I recall).

Im not sure if this is the proper way to go about checking them for shorts but I thought it was worth a try to see what I could find out.
The search continues...

[KYBOSH]

Ok, so what was the vgl, vgh etc. readings on the tcon? When those correct voltages are missing it may very well be a sign of a panel short.

I dont recall checking those before but I will have a look on my TCon to see if I can spot the test pads.
Another (seemingly sure fire) way i have seen on Youtube it to tap the blank screen when the power is on.
You will see flashes of white light pop up. I have done this and this TV responds in this way.

[KYBOSH]

Check the resistance of each pin relative to GND.

I spot checked those already but using the ground from the chassis. but i went back just now to check again will check again (with the grounds you specified) and they are all showing as not shorted . I will post the resistances shortly.

Edit to Add:
The ones you asked to to measure show a resistance of 2.34-2.35MΩ on each of the legs of 6 legged SMDs (rectifiers?.
The 2 legged device reads 2.468MΩ.

Curiously on the panel board on RIGHT side, the same SMDs all read as OPEN (no resistance at all).

[Diah]

why you are jumping between youtube... u will never have answer there,,, just answer lotas last question.. if they are fine then u need to take out the bezel and carefully with loop check the round display glass

[KYBOSH]

why you are jumping between youtube... u will never have answer there,,, just answer lotas last question.. if they are fine then u need to take out the bezel and carefully with loop check the round display glass

I updated the post the data lotas requested. But i think your low opinion of youtube videos and tutorials isnt quite right or fair. A lot of amazing and informative things there and im quite appreciative of the content creators efforts. Of course not everyone or everything is good on their but a lot of it is.

[nomoresonys]

I updated the post the data lotas requested. But i think your low opinion of youtube videos and tutorials isnt quite right or fair. A lot of amazing and informative things there and im quite appreciative of the content creators efforts. Of course not everyone or everything is good on their but a lot of it is.

Gotta say plus 1000, some very bright individuals lending their expertise and of course a few not so good.