Sunday, February 1, 2015

New Project (Finished too) - Computer Charger Repair

The output wire from my laptop charger frayed and shorted about a year ago. The wire was built into the charger and broke right where it came out of the charger. I couldn't do without my laptop so I had to get a new charger. I kept the broken one so I could repair it and have a spare at some point. There wasn't enough wire left out of the charger to simply solder the cable back together, so I knew it would need a full case replacement. I also wanted to add a second connector so I could remove the output cable and a similar break in the future.

The charger appeared to be one solid piece of plastic. There were no seams or obvious places to try prying the charger apart. I managed to chip away the rubber that sealed the output cable to the charger. The small opening let me look inside and determine the wall thickness of the charger's case. I could also see the orientation of some of the internal components. I guessed the circuit board was inserted right-side-up into the charger during assembly which led me to guess which side was the lid.

I used a mill to cut away just the outer wall of the charger. I stepped down a small amount with each pass until the top lid broke free. It turned out to be held in with plastic snaps. I believe the lid was glued or friction welded to the rest of the case. It was a clean, but unrepairable design. I managed to avoid cutting any of the components.

The charger had pretty simple internal geometry. I reversed engineered the critical geometry in the case to hold the remaining components.

I bought a pretty nice looking connector without looking at the dimensions... The connector wasn't going to fit in the original case geometry, so I was forced to put it on the lid. I'll admit its a strange form for a charger, but it worked out. I originally planed to use the black resin on my 3D printer to make it look nice, but I got lazy and used the clear resin that was already in my printer.

Here is the main part of the case after it came out of the 3D printer. This is probably the largest part I've printed so far. Thankfully it didn't have a print failure like I had with a few other parts recently.

The lid also printed cleanly. As usual the extra material for the support felt like a waste, but there isn't much I can do to avoid adding it.

I wanted the charger to be symmetrical, so I put screws on the bottom. They don't hold anything together, but they do look nice.

The charger fit snugly into the case. The wall power plug even fit into the case!

Here's the lid before squishing the remaining wires into the charger.

The charger has been revived! The design is pretty strange, but it's functional which is what counts. The upward angle output plug is actually nice because it reduces wire stress when reaching from the floor to a table. It also makes the USB charging port easier to access. I should have been less lazy and printed the charger case in black, but at least the insides are visible like one of the old clear gameboys.

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