Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

[kenney001]

Sony KDL-70R550A

Turns on just fine with button or remote, backlight comes on, but no logo, no menus, no lines, no sound, just a blank black screen with the backlight. When you press remote buttons the status light blinks, so something is trying to work. No red lights at all.

Power Supply is providing the poper voltages to the mainboard. The pins are labelend on the power supply side so I checked them with the set ON. Tcon seems to be getting 12.4v from the mainboard. I checked the fuses I could find, and they seem okay, but there are plenty that are tiny so Im not sure ive found them all.

What else can I try?

Im not 100% that sound doesnt work, but plugging in both component and hdmi and hitting the input button and waiting, and volume up, makes no noise. I cannot see anything otherwise.

[budm]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

https://www.badcaps.net/forum/showthread.php?t=39740

[kenney001]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

My appologies. Here you go.

If I unplug the backlight from the power supply, i get 6 red blinks. If I remove the TCon completely, status light stays green and functions exactly as it does with it in. I dont know if this helps any

[budm]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

Try having just one ribbon cable between the T-CON board and the LCD panel one at time to see what you get.

[kenney001]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

With just the left ribbon in, I got the same blank screen. With the right ribbon in however, i got this:

[budm]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

OK, we will need really good pictures of the T-CON board to see if we can locate the Voltage test points.

[kenney001]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

Here you go. The red arrow is where I tested 12.4v.

Anywhere else is covered by the metal heatsink/bracket. Is it safe to turn the unit on with the heatsink off?

[nomoresonys]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

also try a firmware update, thats if you can find one on sony, they like to take m off the site, way too soon, guess they're hoping people will keep buying their products, even without much support.

[budm]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

Here you go. The red arrow is where I tested 12.4v.

Anywhere else is covered by the metal heatsink/bracket. Is it safe to turn the unit on with the heatsink off?

There is not any labeling for any of the test points on the board at all.

[schulte2000]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

I have a Sony Bravia KDL-70R550A doing a very similar thing as you describe... a blank screen (backlit), green status light (blinks with remote clicks). I have used shopjimmy to replace the TCON, Main Board, and Power Board and still having the same issue. Did you ever figure your issue out and could you share what you did as I am fearing I have a very expensive piece of trash?

I read the suggestion to update the firmware, but there is nothing displaying on the screen so there is no way to do that. I have also tried to perform the reset as Soný's site suggests but it does not reset at all. I just see the blinking green light as I hold the up arrow and then push/release the power button on back of TV and nothing. TV just stays on with the green status light (blank screen - no picture)

[gormanrider8]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

Hi there, I'm new here but have been following many threads to attempt to repair my Sony Bravia KDL-70R550A. My symptoms are identical to schulte2000 above me: No image/blank screen, possibly no sound but hard to confirm, Backlight ON, green status light responds to remote commands.

I replaced the TCON board already and yielded the same results. I measured power on the power supply board at the connector to the main board and the "T-CON_12V" is at 12.5V, the "REG12V" is oddly 13.0V, and the "3.3VSB" is 3.3V. This assures me the power supply board is good, also because the LED backlights work. Is the poorly regulated "REG12V" at 13V a problem for the main board? The voltage directly on the TCON board is 12.5V.

This all makes me believe the main board is the culprit but I am hesitant to replace it since I got the TV free to try to revive it. I am worried I will replace it and do what schulte2000 did and have it still not work. What else could the issue be? The ribbon cables to the panel? Or the LCD panel itself? Any help would be much appreciated.

- Tyler

[freakaftr8]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

No. Try disconnecting one ribbon cable at a time from tcon to panel. Try with just the left side plugged in, if nothing, then try the right. Well go from there.

[budwich]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

AND post pictures of your results of the "ribbon removal tests".

[gormanrider8]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

My apologies for the long reply time. I finally got around to doing my ribbon cable tests and have found some telling evidence (see attached photos).

With the right ribbon cable removed (see image of ribbon orientation), the right half of the screen worked perfectly and showed the correct picture while the left half of the screen was white. When I removed the left ribbon cable and re-inserted the right ribbon cable, the screen had strange green and yellow vertical stripes on the left half of the screen and faint grey horizontal lines on the top of the right half of the screen.

This leads me to believe the right ribbon cable or connecter/headers at one end of the right ribbon is bad. In both cases I only removed the ribbon cable from the connectors on the TCON board side. I checked both ribbon cables at the TCON side and all contact marks looked clean and not near the edge or shorting any other traces. If anyone has any further advice following these results it again would be much appreciated. Your previous feedback led me to not giving up on the TV so thank you.

- Tyler

[gormanrider8]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

My apologies for the long reply time. I finally got around to doing my ribbon cable tests and have found some telling evidence (see attached photos).

With the right ribbon cable removed (see image of ribbon orientation), the right half of the screen worked perfectly and showed the correct picture while the left half of the screen was white. When I removed the left ribbon cable and re-inserted the right ribbon cable, the screen had strange green and yellow vertical stripes on the left half of the screen and faint grey horizontal lines on the top of the right half of the screen. With both ribbon cable removed the screen was all black with backlight still on.

This leads me to believe the right ribbon cable or connecter/headers at one end of the right ribbon is bad. In both cases I only removed the ribbon cable from the connectors on the TCON board side. I checked both ribbon cables at the TCON side and all contact marks looked clean and not near the edge or shorting any other traces. If anyone has any further advice following these results it again would be much appreciated. Your previous feedback led me to not giving up on the TV so thank you.

- Tyler

-->Ribbon Cable/TCON Orientation

-->Screen with LEFT ribbon cable REMOVED

-->Screen with RIGHT ribbon cable REMOVED

[easy2know]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

My apologies for the long reply time. I finally got around to doing my ribbon cable tests and have found some telling evidence (see attached photos).

With the right ribbon cable removed (see image of ribbon orientation), the right half of the screen worked perfectly and showed the correct picture while the left half of the screen was white. When I removed the left ribbon cable and re-inserted the right ribbon cable, the screen had strange green and yellow vertical stripes on the left half of the screen and faint grey horizontal lines on the top of the right half of the screen. With both ribbon cable removed the screen was all black with backlight still on.

This leads me to believe the right ribbon cable or connecter/headers at one end of the right ribbon is bad. In both cases I only removed the ribbon cable from the connectors on the TCON board side. I checked both ribbon cables at the TCON side and all contact marks looked clean and not near the edge or shorting any other traces. If anyone has any further advice following these results it again would be much appreciated. Your previous feedback led me to not giving up on the TV so thank you.

- Tyler

-->Ribbon Cable/TCON Orientation

-->Screen with LEFT ribbon cable REMOVED

-->Screen with RIGHT ribbon cable REMOVED

Hi gormanrider8, did you manage to fix your TV?

[Lyle Beach]

Re: Sony KDL-70R550A No Picture, No Sound, Backlight ON, Green status light

I'm also in the same boat with this TV. Any luck on a fix?