A cousin of mine bought me a cell phone for repair. He explained that, the phone was not charging and it does not come on. Of course I have my own easement to find out the fault so let us begin.

I tried to do a hard reset to the phone by pressing and holding the power key with the down volume button and the home key for about ten seconds and it should start but it did not start. I guess the battery is not charged enough to get the phone started.

The other option is to get inside the phone and find out the problem with the phone not starting. Let the fun begin.

The back side was easy to come off and in order for me to get inside the phone I need to take about 18 tiny screws off. Be careful with these screws. They are so tiny that they can be lost so easily.

Screws off and back off, finally I got to the main logic board. Unhooked both the flex cables of the screen and the vibrator motor; the board is detached from its housing.

It seems brand new on the inside and a quick check under my microscope found nothing burnt or lost components.  My attention was focused on open fuses or other components that may be have loose connections; all checked fine.

From research on the net, I looked for the charging IC on this device. I was getting voltage reading on the main input of the IC but for some reason, it was not charging the battery. I usually replace the IC but before doing that, I thought of re-flowing the IC without taking it off board.

The IC part number is MU005x1-2. I looked or it on board and when I found it I used my brand new rework station to reflow the IC and the diode nearby.

You can see the IC and the diode next to it. On the top of the IC you could see a white spot there but actually this white spot was left over thermal paste used by other technician to cool down the IC. I added some flux paste on both of the IC and the Diode and re flown them carefully. The idea here is to heat up the IC carefully enough to take it off board but to heat it up enough to let it dance a little bit then hot air off and let it sit down nicely.

After the process was done, I gave some time for the IC and the area around it to cool down. I assembled everything back together to check if this process worked or I have to replace the IC?

Well, it worked well. Of course I kept it one for a while till the customer came and picked it up. So the phone was not for my cousin, it was for my cousin’s son who dropped this phone so countless times on the floor.

As you can see, the phone is working fine and the only thing was left to do is to adjust the time and date on this phone. Mission Accomplished.

This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.

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Note: You can check his previous repair articles in the link below:

https://www.electronicsrepairfaq.com/how-to-repair-intermittent-problem-in-inverter-welder