Keysight Technologies N5247B, Service Manual

Page: 501 / 566

Keysight N5247B Service Guide 7-57
Repair and Replacement Procedures
Removing and Replacing the A50–A53 Bypass Switches and the A54 Combiner
Removing and Replacing the A50–A53 Bypass Switches and the
A54 Combiner
Tools Required
T-6 TORX driver (set to 4 in-lb
— 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 7-28 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. The bypass switches and the brackets to which they are attached, must be
removed as a complete assembly.
Disconnect all eight semirigid cables (item

) from the bypass switches
on the bracket to be removed.
If removing the A54 combiner, disconnect three semirigid cables (item

)
from it.
5. Remove four screws (item

) that secure the switch bracket to the test
set deck.
6. Move the disconnected semirigid cables out of the way and remove the
switch bracket, with the bypass switch attached, from the analyzer. It may
be necessary to loosen the connector at the other end of some of the
semirigid cables to allow them to be moved.
7. Disconnect the wire harness cable of the bypass switch to be removed
from the test set motherboard.
8. Remove two screws that attach the bypass switch or the A54 combiner to
its bracket.
IMPORTANT!
When an attenuator or a bypass switch is replaced in a PNA-X, 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.