Keysight Technologies N5247B, Service Manual

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Keysight N5247B Service Guide 7-41
Repair and Replacement Procedures
Removing and Replacing the A27 and A28 Mixer Bricks
Removing and Replacing the A27 and A28 Mixer Bricks
Tools Required
— T-8 TORX driver (set to 6 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 7-19 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. Remove the A26 splitter. Refer to “Removing and Replacing the A26
Splitter” on page 7-39 .
5. The mixer bricks and the mounting blocks to which they are attached,
must be removed as a complete assembly.
Disconnect all semirigid cables (item

) from the mixer bricks on the
mounting blocks to be removed.
6. Disconnect the ribbon cables (item

) from each of the mixer bricks.
7. Remove ten screws (item

) from the mixer brick mounting block.
8. Move the disconnected semirigid cables out of the way and lift the mixer
brick mounting block out of the analyzer just enough to allow the gray
flexible RF cables (item

) to be disconnected. 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.
Note the locations of each of the gray flexible cables for reconnection
later. Disconnect these cables and remove the mixer brick mounting block
with the mixer brick(s) from the analyzer.
9. If replacing a mixer brick, remove 3 screws (not shown) that fasten each
mixer brick to the mixer brick mounting block.
10. If replacing the A28 mixer brick, remove the 3 dB pad (item

) and keep it
for reinstallation on the replacement mixer brick.
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.