As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOST CONTROL OF PRESSURIZATION, INITIALLY UNABLE TO CONTROL IN STBY, WENT TO MANUAL REGAINED CONTROL THEN TRIED STBY AND THE SYSTEM FUNCTIONED NORMAL. REPLACED THE NR 1 TRANSFER BUSS BREAKER AND RELAY. (THIS POWERS THE PRESS AUTO AC C/B . PERFORMED CHECK OF PRESSURIZATION CONTROL IAW MM, OK FOR SERVICE.