Loose internal wiring harness; cracked solder joint on ports.
The is an emergency power supply unit commonly used in aircraft to provide backup power for essential flight instruments, such as gyro horizons. Maintenance for this unit is typically governed by the L3Harris (formerly J.E.T. or B.F. Goodrich) Component Maintenance Manual (CMM) TP-483 . ps-855b maintenance manual
By adhering to the maintenance schedules and procedures outlined in the official documentation, the PS-855B will provide reliable emergency power for years. If you are currently maintaining this unit, you can: Loose internal wiring harness; cracked solder joint on ports
The manual will list a pre-service checklist: If you are currently maintaining this unit, you
Comprehensive Guide to the PS-855B Maintenance Manual The PS-855B Component Maintenance Manual (CMM)
Check the DMM reading. If it does not read 10.00V , locate the internal voltage calibration trim pot (typically labeled or VR1 on the display control PCB).