Sony XBR-55X900F No picture, no sound no backlight

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

Need schematic or some reverse engineering. Luckily I have the exact board in hand haha...

• Traced REG12V to 5x DCDC for reduced voltages. Check voltage at all 5 points labeled 12V-A->E. Probably all 0V.
  
• Check the 3 components between where REG12V comes into main and the GND plane right below it. See if any are shorted.

BTW SONY boards are nice... lots of holes on voltage rails and have exposed copper for easy test

Yes they are very nice! Very easy to do the checks you wanted.

12V A through E have ~12.65 VDC

3 components on REG12V input are good. (no shorts)

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

Is there voltage at all on this connector, are these input fuses intact?

Yes, voltages are present and fuses are good.

[howardc64]

Re: Sony XBR-55X900F No picture, no sound no backlight

Yes they are very nice! Very easy to do the checks you wanted.

12V A through E have ~12.65 VDC

3 components on REG12V input are good. (no shorts)

wow, thats 5 different DCDC paths all with 12v input. Are you sure all the coils/inductors next to them shows 0V DC on both sides? Sometimes its hard to actually get the probe on the contacts buried on the bottom.

On REG12V, what is AC reading? AC just shows how much noise is above DC. We want to see near 0 for clean stable 12V DC.

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

wow, thats 5 different DCDC paths all with 12v input. Are you sure all the coils/inductors next to them shows 0V DC on both sides? Sometimes its hard to actually get the probe on the contacts buried on the bottom.

On REG12V, what is AC reading? AC just shows how much noise is above DC. We want to see near 0 for clean stable 12V DC.

Voltages are present....1.1VDC, 1.5VDC, 1.0VDC, 3.3VDC, 5.1VDC. I measured across instead of to GND.

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

No ripple on the DC. Nothing my DMM could read anyway..

[howardc64]

Re: Sony XBR-55X900F No picture, no sound no backlight

Voltages are present....1.1VDC, 1.5VDC, 1.0VDC, 3.3VDC, 5.1VDC. I measured across instead of to GND.

Ok CPU has power. Heat sink on the right is the SOC/CPU and should be warm.

Check SPDIF (optical connector next to ethernet) and see if red light inside the door. This provides hint on how far CPU got in booting itself up.

How about TV's power standby LED? Does it flash ever? (plug in AC, press power button etc..)

What voltage does the coil/inductor read at IC501? Board still have a 1.8V somewhere for eMMC IO voltage. IC501 is just above SOC so might be it.

Heat sink on the left is LCD processor and since this tv has zoned backlight, probably also calculate individual backlight brightness level and forward to other boards to drive the zoned backlight brightness. Any warmth on this heatsink? Probably not if you have no t-con on and t-con voltage.

eMMC PN on the board should be H26M52208FPR. Same Hynix flash memory generation as my HiSense thread ( link ) that show it likely died. This one is 16GB (mine was 8GB) Lets hope yours is not eMMC death. Know any usage history? I recently fixed a couple of LGs that was on average of 8 hours a day for 3-4 years and wore out the backlight LED's yellow phosphor filter and turn it blue.

[howardc64]

Re: Sony XBR-55X900F No picture, no sound no backlight

This video is not your TV but 28pin connector PSU connector appears to be same. He jumped 3.3V STANDBY to POWER_ON and TCON_ON to confirm PSU can generate TCON_VCC12V. Probably don't need to do this yet but just stay informed

https://www.youtube.com/watch?v=Y00I...ck%27sTVRepair

He fixes a ton of these SONYs where the main board failure is always eMMC (he has lots of videos on this). No same main boards as yours (but likely same main SOC and similar eMMC generation from Samsung and Hynix. Has other videos of SONY dying ( link ) with same gen Hynix eMMC as your. All of these are also Android TVs which is also mine HiSense with dead eMMC.

Anyway, Just FYI as diagnostic continues. I might have seen this movie before : Android TV, all voltages on main except t-con, no backlight, no standby light etc. Just dead because CPU can't boot with failed eMMC. Not much info on cheap HiSense but more repairs done on higher end SONYs.

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

Thanks howardc64, I will check this all out. But based on what you said, and links provided it probably is the eMMC eh? Does that basically mean board replacement?

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

The eMMC is a 16GB Samsung KLMAG1JENB-B041 (S5YGGMJ0S)

[Diah]

Re: Sony XBR-55X900F No picture, no sound no backlight

it could be there SOS signal caused by open circuit at panel. disconnect at time on side of the panel or in case there are U ribbon on buffer boards you can also try disconnect one side then turn on see if the BL will turn on.

[howardc64]

Re: Sony XBR-55X900F No picture, no sound no backlight

Thanks howardc64, I will check this all out. But based on what you said, and links provided it probably is the eMMC eh? Does that basically mean board replacement?

Require more diagnostic effort to be more certain. TV's user manual ( link ) shows a 3.5mm audio jack serial port (RS232c, pg11) for remote control. Maybe it will show boot up log msgs? But you will need USB to serial 3.5mm jack dongle. I built one here ( link )

Probably keep on doing other easy diagnostic efforts ( like @Diah's post #30 ) before taking the gamble replacing main board.

The eMMC is a 16GB Samsung KLMAG1JENB-B041 (S5YGGMJ0S)

Yes, looks like all these SONY Android TVs are getting eMMC failure in both Samsung and Hynix brands.

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

https://www.badcaps.net/forum/showpo...2&postcount=28

Require more diagnostic effort to be more certain. TV's user manual ( link ) shows a 3.5mm audio jack serial port (RS232c, pg11) for remote control. Maybe it will show boot up log msgs? But you will need USB to serial 3.5mm jack dongle. I built one here ( link )

Probably keep on doing other easy diagnostic efforts ( like @Diah's post #30 ) before taking the gamble replacing main board.



Yes, looks like all these SONY Android TVs are getting eMMC failure in both Samsung and Hynix brands.

Could you please provide the link to build the dongle. It didn't work in your last post.

[howardc64]

Re: Sony XBR-55X900F No picture, no sound no backlight

Could you please provide the link to build the dongle. It didn't work in your last post.

sorry formatting error and link was on top. Fixed now. Anyway link is here again

https://www.badcaps.net/forum/showpo...2&postcount=28

fastest cheap dongle ( link ) from Amazon with Prime in US. ebay 2nd fastest. AliExpress cheapest + slowest.

Can buy multiple dongle specs. CH340G is good enough. Set TXD/RXD to 3.3V (use jumper thats pointing up. Here is final product

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

Ok CPU has power. Heat sink on the right is the SOC/CPU and should be warm.

Check SPDIF (optical connector next to ethernet) and see if red light inside the door. This provides hint on how far CPU got in booting itself up.

How about TV's power standby LED? Does it flash ever? (plug in AC, press power button etc..)

What voltage does the coil/inductor read at IC501? Board still have a 1.8V somewhere for eMMC IO voltage. IC501 is just above SOC so might be it.

Heat sink on the left is LCD processor and since this tv has zoned backlight, probably also calculate individual backlight brightness level and forward to other boards to drive the zoned backlight brightness. Any warmth on this heatsink? Probably not if you have no t-con on and t-con voltage.

eMMC PN on the board should be H26M52208FPR. Same Hynix flash memory generation as my HiSense thread ( link ) that show it likely died. This one is 16GB (mine was 8GB) Lets hope yours is not eMMC death. Know any usage history? I recently fixed a couple of LGs that was on average of 8 hours a day for 3-4 years and wore out the backlight LED's yellow phosphor filter and turn it blue.

No red light at optical, no standby light at any point. I think you meant IC601? The coil there is about 1.5VDC

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

it could be there SOS signal caused by open circuit at panel. disconnect at time on side of the panel or in case there are U ribbon on buffer boards you can also try disconnect one side then turn on see if the BL will turn on.

No change. Dead dead dead lol

[lotas]

Re: Sony XBR-55X900F No picture, no sound no backlight

No change. Dead dead dead lol

Here the problem is in the motherboard and rather in eMMC, and if the problem was in the panel, then the TV would turn on exactly and give an error "5".

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

Alright, so I guess need to find a replacement motherboard.

[lotas]

Re: Sony XBR-55X900F No picture, no sound no backlight

Alright, so I guess need to find a replacement motherboard.

Look for a better native kit (Mainboard + T-con), there will be less problems to cross them (this is SONY).

[Nicktronic]

Re: Sony XBR-55X900F No picture, no sound no backlight

Just to wrap up this thread, I received a new Main Board. As @lotas mentioned, it was not paired with the existing T-Con. I was able to follow this video to pair the boards and it's working great!

https://youtu.be/3kYPjIHt8Lc (Mine worked after re-naming the file)

Thanks for all the help!

[nomoresonys]

Re: Sony XBR-55X900F No picture, no sound no backlight

Nice save, how much are those mainboards? wonder if they have them for the 900C.