FCO DEFEB-F001, Fan circuitry malfunctions

This Field Change Order (FCO DEFEB-F001) addresses a malfunction in the fan sensing circuitry of DEFEB-AA and DEFEB-AB units with Application Modules (Part No. 54-19375-01) below Revision "B1". The problem manifests as inaccurate fan status indications, either showing properly operating fans as malfunctioning or vice versa.

The solution involves replacing the affected Application Processor (AP) Modules (54-19375-01) with modules at Revision "B1". The rework procedure requires obtaining customer permission, safely disconnecting the unit from the network and power, recording switch settings, carefully removing the old AP module, installing the new Revision "B1" AP module, setting its switches to match, and then reconnecting and verifying system operation. It also emphasizes the importance of reloading management data, using ESD precautions, and following safety guidelines when handling components and fiber optics. The process is estimated to take 1.0 hour.