Keysight Technologies N5247B, Service Manual

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7-66 Keysight N5247B Service Guide
Repair and Replacement Procedures
Removing and Replacing the A57 Port 2 Noise Bypass Switch (Option 029)
7-
Removing and Replacing the A57 Port 2 Noise Bypass Switch
(Option 029)
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 7-33 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 four semirigid cables (item

) from the A57 port 2 bypass
switch.
It may be necessary to disconnect or remove other cables to gain access.
If you do, make note of these cable connections for reconnection later.
5. Disconnect the A57 bypass switch wire harness cable (item

) from the
A59 noise receiver (downconverter). Make note of the routing of this wire
harness so that the wire harness for the new bypass switch can be routed
in the same manner.
6. Remove two screws (item

) that secure the switch to the switch bracket.
7. Move the disconnected semirigid cables out of the way and remove the
switch from the analyzer. It may be necessary to loosen the other end of
the cables to allow them to be moved. Do not overbend them.
Replacement Procedure
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.