Keysight Technologies N5247B, Service Manual

Page: 495 / 566

Keysight N5247B Service Guide 7-51
Repair and Replacement Procedures
Removing and Replacing the A38–A41 Source Attenuators and the A46–A49 Receiver
Attenuators
Removing and Replacing the A38–A41 Source Attenuators and the
A46–A49 Receiver Attenuators
Tools Required
— T-10 TORX driver (set to 9 in-lb)
— T-20 TORX driver (set to 21 in-lb)
— 5/16-inch open-end torque wrench (set to 10 in-lb)
— ESD grounding wrist strap
Removal Procedure
Refer to Figure 7-24 for this procedure.
1. Disconnect the power cord.
2. Remove the outer cover. Refer to “Removing the Covers” on page 7-6 .
3. Position the analyzer bottom side up.
4. Disconnect the ribbon cable (item

) from each attenuator to be
removed.
5. The attenuators and the brackets to which they are attached, must be
removed as a complete assembly.
Disconnect two semirigid cables (item

) from each attenuator to be
removed. It may be necessary to remove additional cables to remove the
attenuator bracket. If so, note the location and orientation of each for
reinstallation later.
6. Remove four screws (item

) that secure each attenuator bracket to the
test set deck.
7. Move the disconnected semirigid cables out of the way and lift the
attenuator bracket out of the analyzer, with the attenuator attached. It
may be necessary to loosen the connector at the other end of some of the
semirigid cables to allow them to be moved enough.
8. Remove two screws (not shown) from each attenuator to be removed from
the mounting bracket.
IMPORTANT!
When an attenuator or a bypass switch is replaced in a PNA, it is important
to reset the Mechanical Counter setting. Refer to “Resetting the
Mechanical Counter” on page 7-101 .
Be careful not to damage the center pins of the semirigid cables. Some
flexing of the cables is necessary to remove the assembly. However, do not
over-bend the semirigid cables.