HP 70908A, Service Manual

Page: 308 / 335

A15 RF 1st Converter
A15 RF 1st Converter
CA UTION
This module contains components that can be damaged or destroyed by
electrostatic discharge . It should be serviced at a static-safe workstation.
(Refer to \Preparing a Static-Safe W ork Station " in Chapter 4.)
T o Remove the A15 RF 1st Converter
1. Remove the module cover . (Refer to the \Module Cover" procedure .)
2. Remove the A10 power supply/driver . (Refer to the \A10 P ower Supply/Driver "
procedure .)
3. Remove the one screw (1) that holds the rear-panel to the module center casting, and the
three screws (2) that hold the rear-panel to the module base .
4. Disconnect W20 (3) and W21 (4) from the attenuators on the A1 leveling amplier (5).
5. Swing the rear-panel out of the way . Do not distort or damage the cables .
6. Disconnect W19 (6) from the A1 leveling amplier (5) and the A15 RF 1st converter (7).
7. Loosen the elbow connector (8) one turn at the A2 LO multiplier . (If the elbow connector
is loosened more or fewer turns it may crack during the rest of the removal process .) Do
not crack the connector , or damage the wires near it.
8. Remove the ten screws (9) that hold the microcircuit assembly (10) on the center casting.
9. Finish disconnecting the elbow connector (8) while sliding out the microcircuit assembly .
10. Loosen W25 (11) at A16 low pass lter (13).
11. Loosen W24 (12) at A17 low pass lter (14).
12. Disconnect W25 (11) and W24 (12) from the A15 RF 1st converter (7).
13. Remove four screws (15).
14. Remove the A15 RF 1st converter (7).
15. Remove W19 (6) from the A15 RF 1st converter.
T o Replace the A15 RF 1st Converter
1. Connect W19 (6) to the A15 RF 1st converter (7).
2. P osition the A15 RF 1st converter (7) in the module .
3. Replace the four screws (15).
4. Connect W25 (11) and W24 (12) to the A15 RF 1st converter (7) IF and RF connectors .
5. Tighten all connectors on cables W25 (11) and W24 (12).
6. Slide the microcircuit assembly (10) back into the module , lining up the elbow connector (8)
and the A2 LO multiplier OUTPUT connection; tighten the elbow connector only one turn.
7. With the microcircuit assembly at against the casting, replace the ten screws (9) that hold
it in place . The screws should be two turns short of being tight (for example , fasten the
screw down, and then loosen it two turns).
8. T orque the elbow connector (8) to 10 inch-pounds .
9. T orque the ten screws (9) to 9 inch-pounds .
10. Reconnect W19 (6) to both the A1 leveling amplier (5) and the A15 RF 1st converter (7).
11. P osition the rear panel against the module; do not damage the rear-panel
ground spring (15) .
12. Reconnect W20 (3) and W21 (4) from the attenuators on the A1 leveling amplier (5).
13. Replace the three screws (2) that hold the rear-panel to the module base . T orque the
screws to 20 inch-pounds .
14. Replace the one screw (1) that holds the rear-panel to the module center casting. T orque
the screw to 6 inch-pounds .
15. Replace the A10 power supply/driver . (Refer to the \A10 P ower Supply/Driver "
procedure .)
16. Replace the module cover . (Refer to the \Module Cover" procedure .)
Replacing Major Assemblies 9-41