My good friend James contacted me with an electronics problem. Seems his daughter’s cell phone was on the fritz. So I agreed to take a look.
She has a Pantech P7000 flip phone, but it stopped charging. I asked a few questions first to understand the nature of the problem. For instance:
- Has she tried other wall chargers? Yes, all give same symptoms.
- Has she tried other batteries? Unknown.
- Has she tried wiggling the cable to see if it makes connection? Yes, and it does.
James gave me some great info, so I knew what I was in for. My guess was that the charging connector on the phone was going bad. I’ve seen it before. James sent it to me to have a look:
The first thing I did was have a look at the charger, just to test out the verbal info I gathered from James. With a set of helping hands, I probed out the power and ground pins:
I saw a nice steady +5V, so the charger was good. Although its plastic shell was a bit wobbly, it seemed to be functional still. Now, onto tearing apart the phone.
I couldn’t find a tear-down guide online, so I had to figure it out for myself. There’s one obvious screw above the battery compartment:
But I had a hard time finding the other hidden screws. Turns out, there are four hiding underneath a bezel surrounding the keyboard:
Once those are gone, the assembly comes apart rather easily:
Now the back shell can be removed. When I did, the charging connector tumbled right out. So it was no longer even attached to the PCB:
Here is a closeup of the connector:
You can even make out the copper pads still attached to the pins, which have ripped off of the PCB. That’s never a good thing! This type of damage is actually quite common in consumer electronics. This interface isn’t always well designed on most cheaply produced gizmos. And yet, it’s an area that is very high-traffic; in other words, the mating cycles of the charger or serial cable to the phone is always quite high. As a designer, I would prefer these interfaces to be more robust. But then, I’m more interested in lifespan of my electronics, whereas most electronics companies would prefer you buy new products every 6 months. I digress.
At this point, I wasn’t yet sure I could repair this. There was significant damage to the PCB pads (some pads entirely gone!), so I first cleaned off the remaining pads by re-tinning 1:
Next, I cleaned off the pins of the connector. Then I re-placed the connector down on the board and soldered it back on. I got maybe 80% coverage of pins to pads. The number of pins on this connector is maybe 10-12; obviously only 2-4 of which are used for the power charger. So all that was strictly necessary were those sets of pins. As luck would have it, those power pins were still intact. The phone is back to life!