Solved! iPhone SE random restart - The rabbit hole

Jan 24, 2019
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Hello all,

I have a iPhone SE which went through a 15 minute laundry cycle.

After removing it from the machine I opened it up right away and disconnected the battery.

I then dried it all out and removed the logic board. I then proceeded to remove the shields and found humidity all over the logic board. After being certain everything was dry I tried powering on the phone but nothing happened.

This was when I red up about cleaning the board with a ultrasonic bath. I have access to one at the place where I work so I used it with de-ionized water, seeing as how I didn’t have any electrical cleaner.

The board was set in the bath four times for a duration of approximately 60 minutes each time. After each cycle I cleaned the board with isopropyl alcohol and a tooth brush. I don’t have a stereo microscope so I used a set o jeweler magnification glasses in order to check for any corrosion and shorts. The board looked very clean, almost like new. Finally I managed to get the phone to turn on completely and charge up.

After charging up completely I left the phone on my desk for a while and pulled all of the old information off and updated iOS. The phones works normally, however I noticed the battery drains very quickly and the phone will randomly restart when the battery is between 100%-75% and 1% and 10%. The gyroscope also doesn’t work, the compass is “frozen” and will not move, however this doesn’t really bother me much, for now.

I did all of the usual hard reset, DFU mode and iOS update but the battery drain and compass remain the same.

In the process I let the battery charge completely and checked the voltage, 4.32 VDC. I kept checking the voltage without ever connecting it to the pin connector on the board, the voltage remained the same which indicated to me the battery may not be the culprit of the fast drain.

I decided to use the phone for a while and soldered the shields back on and called it good.

More reading/youtube videos and I decided to check the board for any possible short. I had access to a power supply so I set it to the fully charged voltage of the battery, 4.30 VDC.

Placing the positive lead on the positive terminal of the battery connector and the negative on chassis ground, there is a current of 0.043 A or 43mA, however the voltage never drops.

A short is always a short regardless of the amount of current that is getting through, however my question resides in the fact that the phone functions “normally” aside from the battery drain and random restarts. (I don’t feel anything getting warm.) I don’t have any freeze spray, would a upside down can of compressed instrument cleaning air work?

I also tested the board with a multi meter. There is no continuity between the positive terminal and chassis ground and the diode mode reading with negative lead on the positive terminal of the battery connector and the positive lead on the chassis ground is 0.390V. (I’m not sure of the values that would be normal for a perfect board??)

I have attached some pictures of the tests with the power supply and diode mode.

I’m afraid I don’t know which way is out of this rabbit hole.
 

hang-the-9

Titan
Moderator
Did you try a new battery? It is not very odd you have issues with a washed phone like battery failing and the gyroscope not working. Random restarts, there is more to the device than voltage readings you are checking. There are a million tiny connections and components each having to work perfectly for the device to work, voltage readings won't tell you if there is a small wire stress crack in the PCB or some chip issue due to liquid damage.
 

hang-the-9

Titan
Moderator
Did you try a new battery? It is not very odd you have issues with a washed phone like battery failing and the gyroscope not working. Random restarts, there is more to the device than voltage readings you are checking. There are a million tiny connections and components each having to work perfectly for the device to work, voltage readings won't tell you if there is a small wire stress crack in the PCB or some chip issue due to liquid damage.
 
Jan 24, 2019
2
0
10
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Thanks for the answer.

No, I haven't tried a new battery yet..I've been trying to find one in second hand thus avoiding the cost of a new one in case the problem isn't from the battery.

Yes I understand that not all readings are straight forward it that sense.

I would just like to know is the readings I have are correct.

Thanks for the help.
 
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