Zenith Z-100 PC series Service Manual page 109

Page
5-2
Troubleshooting
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System Troubleshooting
System troubleshooting using the ROM-based diagnostics is explained in
the service guide for Z-lSO PC Series computers (860-81-1) and in the
Z-IS0 PC Series Base Unit Service Module (860-136). Refer to these
documents, or to the disk-based diagnostics documentation (CB-S063­
28), for more information.
Whenever troubleshooting the system, first check the power supply LEDs
on the backplane board (Figure 5-1). All of these LEDs should be lit
when the computer is on. An unlit -5 VDC LED indicates a backplane
board failure. Any other unlit LED indicates a power supply failure.
Figure 5-1: Backplane Board Power Supply LEDs