As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CAPT'S O2 MASK WILL NOT TRANSMIT. TROUBLESHOOTING REPLACED AUDIO MANAGEMENT UNIT PER MM, NO FIX. RE-INSTALLED ORIGINAL UNIT. RANG OUT WIRES FROM DM23009 TO DM23008AA TO S23001 & TO CAPT PTT ON GLARESHIELD. RANG OUT WIRES FROM AMU TO B23080, M23457 AND TO C23627, FOUND NO FAULTS. TRIED NEW PA-CI CONTROLLER, NO HELP. CLEANED ALL CONNECTORS. O2 MASK OP CHECKED NORMAL.