artisan 8640B - Modulation;Metering Mother Board (A13)

TM 9-4935-601-14-7&P
Model 8640B
Modulation/Metering Mother Board (A13)
SERVICE SHEET 25
SERVICE SHEET A
A1 Assembly Removal Procedure
1. Place instrument upside down and remove bottom cover
(Service Sheet F).
CAUTION
While working with and around the semi-
rigid coaxial cables in the generator, do not
bend the cables more than necessary. Do
not torque the RF connectors to more than 2
inch-pounds.
2. Remove two OUTPUT LEVEL knobs and cursor disc
from front panel. The knobs and disc are secured to
concentric shafts with allen screws in the knobs.
3. Disconnect two semi-rigid coaxial cables from bottom of
the A1A2 Output Attenuator Assy (cable W10 at A1A2J1
and cable W11 at A1A2J2).
4. Disconnect plug P2 from A1A1 RF Vernier Assy (located
at rear of A1 Output Level Assy).
5. Disconnect two semi-rigid coaxial cables from bottom of
AS Counter/Lock Assy (cable W2 at A8A1J2 and cable
W14 at A8A11).
6. Remove front side plate cover (item 14 in Figure 6-1)
from right-hand side frame by removing two flat-head
screws.
7. Remove four pan-head screws (with lockwashers) that
secure Attenuator to mounting plate (it is not necessary
to remove the mounting plate). Remove assembly by
sliding it to the rear and up; use care to avoid damage to
gears at front of assembly.
8. Reinstall assembly by reversing the procedure in steps
one through seven.
8-70
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