When proprietary is just awful
Few days ago my wife noticed that her Surface Pro 3 is not willing to charge. Laptop / tablet was working without any problems, except that little light on the charger refusing to stay up and charger just simply not working at all. What a great thing to explore on sunday evening I thought; not really having anything else interesting to do beside going to bed.
Sucking proprietary chargers
Everytime my wife comes to me with some problem related to her laptop, I am celebrating that this time is the time when we will finally get her something more reasonable, like a Lenovo laptop or so, and yet it’s still holding up. Hinting here, that repair was successful.
The annoying thing about all of it is that you can’t just simply buy replacement connector. Though you can buy a lot of USB-C hacky connectors with questionable reviews.
What else remains than go all in…
Stretch, pull, bend, chew…
First of all I had to figure out where the problem lies. Luckily for me there is a USB A port on the charger, that I can use as indicator of charger working. With that in mind and little bit of knowledge about Switch-Mode Power Suplies (SMPS) I have I plugged in USB A volt & amp meter and showed in my USB operated soldering pen to see if it can provide any power at all.
Surprisingly it could. About 5V 1A, which was good sign, untill I touched the chargin connector at the end of the chager. Voltage disappered and whole charger died.
Not great, but… We might have suspect.
Cutting it in a half
From now on, I wasn’t able to find stable position of the cable to measure the output voltages on the conector. I had no other choice than cut the charger cable about 10 cm from the connector. Which brought back my precious 5V 1A, and I found out 2 things..
One of the cables carries the chargin 15V and the other is hanging on 4,2V. I was too lazy to pull out the scope and see if it’s because of some data being transfered, or because of the voltage actually being set by some voltage divider.
What was a win is that output voltage and current was now stable, which means, that problem is in the magnetic plastic piece that goes into the Surface Pro 3 tablet.
Going all in
In this point, I accepted the faith of buying a new charger, so I was wondering what the plastic end has to hide.
After I did that I discovered that the cable is shorting agains it’s shielding. And that there is actually PCB inside. Which gave me new hope!
After desoldering the broken cable out of the PCB I threw those 10 cm away and soldered fresh new cable to the PCB.
Was lucky this time
It just worked. After more pulling, bending, and chewing it didn’t shorted the charger. So I added some hot glue, duct tape, and it just works.
