Max-air capr repair

TROUBLESHOOTing

Gaia had been handling all the CAPR repairs, but this one was beyond her. It was just reported as “broken”. When the power was connected a whole lot of nothing happened. After carefully removing the PCB from the rest of the helmet, i started identifying what ICs did what, and understanding the general circuit design. I learned some interesting things about their device.

After connecting power, i started probing various parts of the circuit, and noticed that the 5v rail was shorted to ground. Not good at all. After following the pcb traces backwards, i noticed damage to the 5v buck regulator. The chip’s marking were decimated, so identifying what it used to be was not going to be easy. I removed the offending chip with a hot-air rework station. After removal, the short was gone. That’s a good first step!

Luckily i happened to have a few Polou buck voltage regulator breakouts on a shelf at home, and managed to install a few wires from other parts of the PCB to allow the 5v rail to be powered again.

Amazingly, the fan spun up fine. I left it running all night long to make sure it was reasonably reliable, and it passed that test. I wrapped the breakout board up in electrical tape and reassembled the helmet.