PS-855B Maintenance Manual (specifically part number ) is the essential technical document for servicing the L-3 Avionics (formerly JET or B.F. Goodrich) emergency power supply. This unit is a critical safety component that provides 24 VDC and 5 VDC backup power to aircraft instruments like attitude gyros during a total electrical failure. Southeast Aerospace Inc. Key Maintenance Requirements
| Original Part | Type | Modern Substitute | Notes | | :--- | :--- | :--- | :--- | | 2SC5200 (NPN pass) | Power transistor | MJL4281A | Higher SOA, identical pinout | | 1N4148 | Signal diode | 1N4148 (still made) | No change | | 4700µF/50V (85°C) | Electrolytic cap | 5600µF/63V (105°C) | Improved ripple rating | | LM723 | Voltage regulator | UA723 or direct drop-in | Still in production | | 5k pot (voltage adjust) | Carbon potentiometer | Bourns 91A1A-B28-B15L | Sealed, longer life |
Because of this, a generic manual does not exist. Follow this guide to find the correct manual for your specific device.
This section provides instructions for replacing components:
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