Specifications

Power Supplies (continued)
The A1 power supplies are tabulated below.
Power Supply Minimum Maximum Switched
+5 Earth Ref. 4.75 V 5.25 V No
+5 Backplane and Fan 4.75 V 5.25 V Yes
+5 Floating 4.75 V 5.25 V No
+18 Floating 17.6 V 19.9 V No
-18 Floating -19.0 V -16.8 V No
6 Vrms Filament Yes
• Check that the input to the supply voltage regulator is at least
1 V greater than its output.
• Circuit failures can cause heavy supply loads which may pull down
the regulator output voltage.
• Always check that the power supplies are free of ac oscillations
using an oscilloscope.
• All plug-in modules use the +5 V backplane supply. Some plug-in
modules generate their own local power supplies.
Chapter 6 Service
Troubleshooting Hints
166