Service manual

Ch 90-92
GU Measurements 1. Make Hardware Connections
• Turn mainframe power OFF
• Connect DMM leads as shown in Figure 2-5
• Turn mainframe power ON
2. Measure Channel 90 GU Resistance
• Send *RST to multiplexer
• Send CLOS (@nn00) to close chan 90 and 00, where nn = card #
(omit leading zeroes in nn ).
• Trigger the DMM with TRIG SGL and note reading
• Send OPEN (@nn00) to open channel 90 and 00
• Subtract measured value of R41 from DMM reading
• Enter the result in Table 2-2 for Channel 90 GU
3. Repeat for Channels 91 and 92 GU
• Repeat steps 1 and 2 for channels 91 and 92 GU
• Use CLOS (@nncc) and OPEN (@nncc), where nn = card # and cc
= channel # (omit leading zeroes in nn) Use 08 for channel 91 and 16
for channel 92.
Figure 2-5. Ch 90 GU Measurement Connections
Verification Tests 2-7