What could be the cause of this display issue? (photo)

Great troubleshooting idea with the screen mirroring!

I once had an MHL cable, but couldn't find it anymore. So instead, I connected via adb and ran https://github.com/Genymobile/scrcpy(scrcpy).

I can fully operate the device that way, and the (virtual) display is flawless.

Given the age of the device, replacing the screen sadly does not make much economical sense.

Any chance this specific issue could be caused by a broken ribbon cable, though? That I would be willing to order and see if it makes a difference.

The weird thing is that I have almost the same issue with a an old phone (Samsung Note 8). Now I'm wondering if these two issues are related. Really wish there was a guide on how to identify a broken screen vs. broken cable vs. broken board, etc. But maybe that just isn't possible.

Hi @hheimbuerger

I don't know the tablet and I can't see it in this ifixit guide but here's a link to a replacement LCD ribbon cable just to show you the cost. I found it by searching for "SM-T580 LCD ribbon cable" (assumed that the SM-T580 was your model)

Perhaps you could inspect your cable closely using a magnifying glass etc you may be able to verify that all the traces in the flex cable are OK and maybe not that one (or more) is fractured. If there is a fracture you may be able to bypass it by soldering a jumper wire around the broken section

Also ensure that the cable's connector ends are clean and not dirty, corroded etc, the same with the systemboard connector socket that it plugs into which may be preventing a good electrical connection

@jayeff I don't have a photo right now, but pretty sure I already had lifted the screen and the cable underneath was in a similar connector as on the mainboard side, therefore easy to replace.

I'll check the cable with a magnifying glass, good idea!

Is it okay if I use 99% alcohol solution (as I would use to clean thermal paste off a CPU) on the connectors? Any chance this would improve things, or can I cause any damage with that?

Hi @hheimbuerger

99% Isopropyl Alcohol is OK to use to clean the board cable connectors and cable ends etc. as it will remove any contaminants from the surface. Be gentle though especially with the connectors.

Just make sure that there is no power connected to the systemboard when cleaning the flex cable board connectors -disconnect the battery - as even Isopropyl Alcohol can conduct electricity when it is still wet and you don’t want to cause any more problems.

The good thing about it is it evaporates quickly and leaves no conductive residues, especially if it is >90%

Have a good New Year

Cheers

@jayeff I cleaned the flex cable connectors with 99.9% Isopropyl alcohol, after disconnecting the battery, and amazingly enough, after reconnecting everything, the display looked fine for maybe a minute. There was a light flickering, kinda similar to running a CRT on 30Hz or so. Then it slowly degraded again, and two minutes later, I'm back to the old state.

Now, I'm not convinced that my cleaning was what caused the temporary 'repair', nor am I sure that the degradation occured over time and not because of micro movements I made while holding everything together. (And carrying it around to go on a short-lived and premature victory lap in front of my family.