Sony XBR 49x900E - Sound and backlight on but no picture

[DKWS89]

Hey Guys,

So a few months ago my Sony XBR 49x900e TV screen stopped displaying the picture but the backlight comes on and I still get sound when I use the remote and navigate to certain apps. I haven't checked anything with the meter yet but started with ordering some replacement boards. I've tried replacing the BMKS board (used from ebay) and also completed the firmware upgrade based on Nicks TV repairs youtube video. I've also replaced the TCON (twice) and PIB.

All of these changes have resulted in the same issue with no picture. I've also tried disconnecting the ribbons to the screen from the TCON one at a time and have not gotten any change on the screen. Reading through a few of the posts on these TVs it seems like the next starting point would be to check and see if I am getting power to the fuse on the TCON. I am going to check that tonight but wanted to know what other things I could check while I am working on it to try and narrow down if its a bad panel or if the replacement BMKS board was potentially bad as well.

Thanks in advance for any guidance!

[DKWS89]

Tested the fuse at the TCON and I have 12v on both sides of the fuse. Is there a way to jumper the power board on this model to do a color test on the panel?

[DKWS89]

Anyone got any ideas here? Trying to save it from the landfill but kinda at a loss now. Has anyone ever tried disconnecting one side of the display and having it work on this model of tv?

[EazyBone]

[EazyBone]

Wanted to try that one since I found it.

Generally you can disc the main board connector from the PSU and jump tcon on, bl on, ps on together and you should get picture test to cycle on screen. Also disc tcon to main board.

BUT need pics to see what's there. Take closer pics of PSU connections also.

After we see what we working with we can tell you better on how

[DKWS89]

Sorry for lack of pics. Attached a few now. I'll look in the service manual to see if I can figure out the pin out for the main board connector and try jumpering those.

Thanks!

[nomoresonys]

Did you make sure the replacement tcon was a match? usually done by matching up digits of the white barcodes.

[EazyBone]

Would you look at that tiny power board! Lol that's awesome. Yes but make sure main/tcon are disconnected and PSU/main (at main obviously) are disconnect. PSU to BL and PSU to tcon should be connected if all that works out. Then you should be able to test the screen and should cycle through all colors full screen. That should let us know if tcon/panel are good I believe.

[Diah]

i think its had external power supply adapter.... you have sound... but did you check if you have 5V on USB ports ? also did yours audio Optical port lite red ?

if both test answer NO. then BGA issue at the vision Chips, or main CPU, if answer YES... then you need to disconnect the T-CON totally from the system and use external adapter 12V to feed the Fuse on T-CON... use torch light ( because BL will not work) to see if there are RGB color pattern on screen.... if yes the MB defect or BGA... if NO then you have damage on screen edge glass take out the speaker and the metal cover and show here high resolution photo of the complete edge boards

[DKWS89]

Yes, this TV uses an external power supply. I checked both fuses on the power board and have + voltage there when the TV is on so I'm assuming the external power supply checks out.

I read about the models on the TCON causing issues for some which is why I tried a second one. Here are the pictures of the original TCON numbers and the spare I still have. Looks right to me, are the first 2 lines on the white tag on the right part of the SN for the board?

Diah, I can check voltage if needed but can guarantee the USB ports are functional and the optical out is lit up red. I can successfully perform a firmware update via USB.

I haven't tried jumpering the connections yet but next on my list. The image of the wiring chart was what I found in the user manual but the connector has top and bottom ports that aren't shown in the drawing. I believe I identified the wire numbers on the connector by using the jumpers as reference points and continuity checking them back to the power board connector.

This might be an ignorant question but what would you use to jumper the wires on the connector? Just some really thin gauge wire? Or is there something specifically for this I could purchase? Alternatively, it looks easy enough to remove the pins entirely and I could wago clip them together.

Thanks for all the help!

[EazyBone]

Any way you can jumper. You can stick a sewing needle in each pin so it's snug and clip them all together, you can take the wire out of the harness and use alligator clip on them all, whatever works as long as it stays steady and isn't losing connection

[nomoresonys]

Probably ok, but I would check the external power supply, you just put your probes of meter one inside and one outside, had a phone adapter that was like 11.9 that was suppose to be 12 and the damn thing didn't work til I used one that had a full 12v.

[lotas]

Probably ok, but I would check the external power supply, you just put your probes of meter one inside and one outside, had a phone adapter that was like 11.9 that was suppose to be 12 and the damn thing didn't work til I used one that had a full 12v.

At 11.9v, the equipment will work stably if it is designed for 12v and corresponds to the load (amps), but yours did not support the load and the power dropped (it could have dropped to 3v). You just had to replace the electrolytic capacitors in it and that's it, and it would produce stable 12v even under load!

[nomoresonys]

I think you missed the point, that being since the supply wasn't putting out a full 12 volts, my device did not work correctly. No the device DID NOT work stably at all. I do know how to fix external power supply, have fixed many. THIS is what happened, I really don't know why you find the need to doubt my results. I'm going to say it's annoying, maybe I can mention that without the mods losing their minds.

[lotas]

It is necessary to measure the voltage at the output of the power supply under load, and not at idle (without load).
And 0.1v will not play any role.

[nomoresonys]

I know how to measure output load or no load, some devices are more sensitive than others and what I reported is the truth, so you are wrong. You know it's all well and good that you know a lot about electronics and such... BUT you are not the only one in the world who has learned these things and other things too, can you grasp that. My last word about that if you feel a burning need to continue, use pm.