• Introducing XDA Computing: Discussion zones for Hardware, Software, and more!    Check it out!

Light and proximity sensors are not visible (Samsung)

Search This thread

ArturSworsky

Member
Aug 12, 2012
10
3
Hi,
My customer brought to me a Samsung A40 after water damage. After cleaning up and replacing the screen to the original one everything looked great until the first call. It appeared that both the light sensor and the proximity one are not even visible under *#0*# menu. I can easily bypass that by switching the power off button to end the call but since then the smartphone also doesn't turn off the screen :/
I've set to turn off the screen after 15s, udpated the software, performed wipe cache and full factory reset. None of them had worked. Screen if not manually locked remains ON all the time. Can it be connected somehow to the damaged sensors? During the call screen is still blinking.
I would be gratefull for any tip in this case.
I can even root the device to just get rid of that "not turning off of the screen". Is there some app maybe to force screen lock after some time of not active?
BR
 
Last edited:

blackhawk

Senior Member
Jun 23, 2020
5,176
1,495
Check for moisture and/or corrosion on the ribbon cable connectors.
Water damage is unpredictable especially if the battery is not pull immediately.
The best thing to do is flush liberally with anhydrous isopropyl alcohol* and completely dry.
Salt water is always lethal... eventually.


*isopropyl or any solvent will poison LCDs, never use it near them. Use best judgment otherwise.
 
  • Like
Reactions: ArturSworsky

ArturSworsky

Member
Aug 12, 2012
10
3
Check for moisture and/or corrosion on the ribbon cable connectors.
Water damage is unpredictable especially if the battery is not pull immediately.
The best thing to do is flush liberally with anhydrous isopropyl alcohol* and completely dry.
Salt water is always lethal... eventually.


*isopropyl or any solvent will poison LCDs, never use it near them. Use best judgment otherwise.
Thanks for the reply. I've already put the phone apart and cleaned every single pcb, connectors, cables with isopropyl in ultrasonic wash and manually with toothbrush. Left it to complete dry for about 48 hours and put it back together. Before that the phone was completely dead. Now everything is working except those 2 sensors. I don't have any datasheet to this mainboard so i don't even know what else can I measure.
Whole thing happened like 2 months ago and the customer just tried to manually lock the screen but its not always possible and he noticed that his battery is drawing pretty fast due to screen on. On the current stage I'm just looking for some workaround to force the screen sleep and remains until power button pressed.
 
  • Like
Reactions: blackhawk

ArturSworsky

Member
Aug 12, 2012
10
3
What is funny. The screen goes to sleep after 15s when connected to charger and locks after 1 minute just like I've set in the settings...
When it is inpluged from charger screen remains awake all the time :/ Maybe that's some clue for anyone?
More tests: light sensor seems to be working correctly. It adjust brightness when covered and uncovered despite the fact that it is not visible under "sensors" in "*#0*#" menu :D Proximity sensor still doesn't work. When calling someone screen remains black and just flashes from time to time...
But the main problem is still with those screen always awake. It is only going to sleep when connected to PC or charger :/ No moisture visible anywhere. I've found a post with the same problem but there was visible that phone was detecting periodically USB connection when it was unplugged. In my case Samsung is not noticing anything on tray etc. It just remains awake until pressed power button or connected to charger :D

I will try to replace USB charging PCB and give You the feedback
 
Last edited:

blackhawk

Senior Member
Jun 23, 2020
5,176
1,495
Maybe contacts on a BGA chipset corroded and shorted out a logic circuit pathway.
If it's under a chipset... game over, however it may on be an accessible area. Optical aid and good light.

It's also possible the water shorted out something enough to damage a chipset.
 

Top Liked Posts

  • There are no posts matching your filters.
  • 1
    Check for moisture and/or corrosion on the ribbon cable connectors.
    Water damage is unpredictable especially if the battery is not pull immediately.
    The best thing to do is flush liberally with anhydrous isopropyl alcohol* and completely dry.
    Salt water is always lethal... eventually.


    *isopropyl or any solvent will poison LCDs, never use it near them. Use best judgment otherwise.
    1
    Check for moisture and/or corrosion on the ribbon cable connectors.
    Water damage is unpredictable especially if the battery is not pull immediately.
    The best thing to do is flush liberally with anhydrous isopropyl alcohol* and completely dry.
    Salt water is always lethal... eventually.


    *isopropyl or any solvent will poison LCDs, never use it near them. Use best judgment otherwise.
    Thanks for the reply. I've already put the phone apart and cleaned every single pcb, connectors, cables with isopropyl in ultrasonic wash and manually with toothbrush. Left it to complete dry for about 48 hours and put it back together. Before that the phone was completely dead. Now everything is working except those 2 sensors. I don't have any datasheet to this mainboard so i don't even know what else can I measure.
    Whole thing happened like 2 months ago and the customer just tried to manually lock the screen but its not always possible and he noticed that his battery is drawing pretty fast due to screen on. On the current stage I'm just looking for some workaround to force the screen sleep and remains until power button pressed.