Service manual

Ch 90-92
LO Measurements 1. Make Hardware Connections
• Turn mainframe power OFF
• Connect DMM leads as shown in Figure 2-4
• Turn mainframe power ON
1. Measure Channel 90 LO 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 R42 from DMM reading
• Enter the result in Table 2-2 for Channel 90 LO
2. Repeat for Channels 91 and 92 LO
• Repeat steps 1 and 2 for channels 91 and 92 LO
• 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 2-4. Ch 90 LO Measurement Connections
2-6 Verification Tests