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Model 11848A
Schematic Notes
To replace reference deck assembly:
Insert two small posts on right side of reference
deck into bottom row of holes in top side rail. Line
up black plastic plungers with their mounting holes.
Press left side and plungers down into place.
To Access Power Supply Regulators:
Remove strap handle on left side of instrument
(two screws). Remove handle caps (front and rear).
Remove left side cover.
To access A1 Assembly:
Pull up the two black plastic plungers on left side
of reference deck and lift out reference deck
assembly (A6-A9). Insert small post on right side of
reference deck into hole in top row of side rail.
Slide left side of reference deck into slot in bracket
to stand upright.
To close the front panel:
Replace shield on A4 Assembly (four screws).
Align edges of deck with tracks in instrument and
push front panel into place.
To remove A4 Assembly
1. Remove all flexible coax and ribbon cables.
2. Remove 5 screws mounting A4 Assembly to
deck (3 screws, Option 201).
3. For Option 201 instruments remove
semi-rigid cables W34, W35, right angle
adapter, and two screws mounting mixer
bracket.
4. Remove standoffs from four corners of A4
Assembly.
5. Disconnect semi-rigid cables W31 and W32
from their front panel connections J3 and
J5.
6. Disconnect semi-rigid cable W30.
NOTE
J 1 (TUNE VOLTAGE OUTPUT) a n d J 1 1 (TO HP 3561A INPUT)
are not connected to chassis ground.
To access A4 Assembly:
Remove plastic trim strip from top of front frame.
Remove three screws in top of front frame.
Remove three screws in bottom of front frame. Pull
front panel out. Remove shield from A4 Assembly
(four screws).
To replace A4 Assembly:
Reverse the order of the steps in the A4 removal
procedure to replace the A4 Assembly.
Caution
The A4 Assembly should slide to
ward the rear of the instrument
as this semi-rigid cable is loos
ened. If it does not, check to
be sure that all mounting hard
ware (screws and standoffs) for
A3 Assembly is removed.
HP 11848A Shown in Service Position
77
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