Fixing a Bose QC25 with broken ANC battery

For the CQ WPX SSB in March 2026, I was a guest operator at DR1A in Goch. For the event, I got a used Bose QuietComfort 25 headset where the ANC worked well to dampen the noise from the neighboring operators. The headset also worked well on a flight to the 2026 pgconf.dev conference in Vancouver. However, on the way back, the ANC battery went dead about one hour into the flight. I did have a spare battery with me, but ANC wouldn’t power on again. Being in a plane, I couldn’t do much about it, so I just kept using the headset without ANC.

Back at home, I went looking for the problem. The battery is hidden behind one of the ear piece handles. The flap is also the minus terminal, but I couldn’t figure out how this thing is even connected to the rest of the circuits. There had to be a cable, but since it moved very freely, my instincts told me “no way this is connected properly”. May 2026 with the CQ WPX CW came, and I asked a few fellow contesters if they had ever seen the problem before, but no one knew. I did the contest without ANC. Luckily, in CW no one is shouting all the time.

Back at home I then took the headset apart. After some investigation, I figured out which cables are connecting the battery, and behold, the connection to the minus terminal was indeed broken. Pulling on the wire produced a pretty crumpled piece of wire.

Replacing the original wire turned out to be impossible, I couldn’t even get the flap removed. But it turned out there is a big empty spot right opposite of the metal front of the flap, with a nifty slot directly next to it, leading to the part with the PCB. So I curled up some copper wire to improvise a spring, put it there, attached a small wire and ran it to the PCB pin.

ANC is back.

• Afu