[SOLVED] Black Screen on AT&T S3

[gordonfink]

I don't this is the typical black screen of death.

If left off for awhile, the phone will work fine for a few (maybe 8-10) minutes. After that, the screen goes black as soon as it turns on - not even a second. When it goes black, then phone thinks it's still on. If I hit the power button, it will put it in sleep mode. When I hit again, it wakes up, and the screen stays on almost long enough to swipe the lock screen, before it goes black again.

I am wondering if there is something shorted or overheating that would cause that. I did switch batteries with another phone, and that didn't matter.

Any ideas on what could be causing this?

The phone is 4.1.2 stock, not rooted. I did a cache wipe and a factory reset, to no avail. I may to test the board and the screen with other components from other phones, so I can try to at least narrow down where it might be, but I was hoping someone might have seen this before.

Any ideas are greatly appreciated. Thanks much.

 

[gordonfink]

Re: Black Screen on AT&T S3

Update: I switched boards (different carriers), and I could not replicate the problem in either phone. I had hoped that would show that either the board or the LCD assembly was bad, but I didn't learn anything useful either way.

I put the boards back in their respective bodies. It still happens now, but not as often. It also appears to be totally random.

When the screen goes dark, the menu and back buttons are lit. When it went out last night, I could see that there was still some faint background light that I can't see in the day. I pulled up Youtube and did a video, and when the screen went dark, I could still see movement, but couldn't make anything out. So, the phone is still going in the background.

If I push the power button, it sleeps, then push it again, and it wakes up just fine. Sometimes I have to do that 4 or 5 times for the screen to stay on. Sometimes it goes dark after 10 minutes of use, sometimes a half hour, sometimes just a few.

Any help is appreciated.

 

[gordonfink]

Re: Black Screen on AT&T S3

Well, right before throwing the phone into the wall, I noticed a partially removed liquid exposure indicator. I pulled the phone apart to check the motherboard.

In the process of taking it apart, I forgot to take out the SD card. In so doing, it pulled the sim/sd card module off the motherboard. Low and behold, there was a very light corrosive glaze in a few spots under the module.

So, I got out the 99% IPA, and a toothbrush, and cleaned the whole entire board. Since then, it seems to be working fine.

I don't know exactly what part getting cleaned fixed it, because I just cleaned the whole board.

Anyways, maybe that'll help someone with inexplicable issues downstream.