7-52 Service Guide E8364-90038
Repair and Replacement Procedures PNA Series Microwave Network Analyzers
Removing and Replacing the A27, A28, A29, and A30 First Converters (Mixers) and Mixer Bias Board E8362C, E8363C,
E8364C
Removing and Replacing the A27, A28, A29, and A30 First Converters
(Mixers) and Mixer Bias Board
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 7-22 for this procedure.
1. Disconnect the power cord.
2. Remove the outer cover. Refer to “Removing the Covers” on page 7-6. Position the analyzer bottom side
up and raise the receiver deck as shown. Refer to “Raising and Removing the Receiver Deck” on page
7-8 if necessary.
3. With a 5/16-inch torque wrench, disconnect the eight semirigid cables (item
①) and the four flexible
cables (item
➁).
CAUTION Be careful not to damage the center pins of the semirigid cables. Some flexing of the cables
is necessary to remove the assembly. Do not over-bend them.
4. With a T-10 TORX driver, remove the four mounting screws (item
③).
5. Remove the mixer bracket and disconnect the ribbon cable (item
④). Observe the CAUTION above.
6. If replacing a first converter (mixer):
a. Remove the defective mixer from the bracket by removing the attachment screws.
b. Install the new mixer onto the bracket using the attachment screws from the mixer that was
removed. Be careful to properly align the DC feed-through pins.
If replacing the mixer bias board:
a. Remove all four mixers from the bracket by removing the attachment screws.
b. Remove the mixer bias board by removing the attachment screws.
c. Install the new mixer bias board onto the bracket by loosely installing the attachment screws from
old the mixer bias board. Do not tighten them at this time.
d. Reinstall the four mixers using their original attachment screws. Be careful to properly align the DC
feed-through pins.
e. Using a T-10 TORX driver, tighten the mixer bias board attachment screws.
Replacement Procedure
1. Reverse the order of the removal procedure.
2. Perform the post-repair adjustments, verifications, and performance tests that pertain to this removal
procedure. Refer to Table 7-2 on page 7-82.
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