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Workstation 4 and 4 LX Field Service Guide
WS4 Troubleshooting
Testing the Power Supply and System Board Voltages
Testing the Power Supply and System Board Voltages
The following procedure describes how to verify that the internal power supply is
functional then goes on to check the working output voltages of the original
Workstation 4 System Boards, AB28 and ABRD36. To perform these checks, the RF
shield must be removed.
Note that the power supply must be connected to the load created by the system board
in order to produce output voltages.
1. Check the power supply output voltages and the system board +5V to +3V
converter. Figure 3-1 points out where to check each ALWAYS voltage. +3V
ALWAYS is generated by U43 and the output can be checked at L11.
Figure 3-1: Checking the ‘ALWAYS’ Voltages - AB28 and ABRD36 Boards
If none of the ALWAYS voltages are present, check the power supply fuse. This
fuse is located near the AC input connector on the power supply board.
•
If the fuse is OK, but no the ALWAYS voltages are present, check the AC
wiring from the input connector, through the toroid to the input connector and
ground lug at the power supply board.
SHOCK HAZARD
Hazardous AC and DC voltages are present on the power
supply board when the AC power cable is attached to the
workstation.