A Repair Video of Portable USB Charger Reveals that there was Nothing Major Problem and the Circuit now Works Fine

The video below was supposed to demonstrate the repair of this portable USB charger, but as it turns out, it was not an electrical problem rather it was caused by some oxidation on the USB contacts. It seems to work perfectly now. The control chip for the DC/DC converter looks to be this DHMF chip. I have never seen the swoop logo before and can’t seem to find any data on this 5 pin device though. It is probably similar to the LT1302 (PDF) that the Adafruit MintyBoost uses. The circuit is not as efficient as the one developed using the LT1302 though since when drawing 500mA from the output it can maintain very close to 5 volts out (2.5 watts) but needs an input of 3 volt at 1.3 amps to do it (3.9 watts). This gives us an efficiency of about 64% but as per the data from the graph of theLT1302, the circuit gives us a better efficiency of about 86% under the same conditions.
Portable USB Charger
The circuit reveals some design details that I was surprised. The circuit seems to be developed with low cost in mind, this might be the reason for corrosion on the USB jack issue. But the circuit also shows some interesting things as well such as the short preventing shields on the flashlight LED leads and a plastic standoff on the red indicator LED. These are not visible to the user and add assembly time and expense showing that they were trying to make a good product. The PCB looks awesome and has a simple layout.

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