HP 8559A Operation And Service Manual page 294

MODEL 8559A
SWEEP, and FREQ SPAN/DIV knobs.
j. Tighten Stud (53) and left-most Screw (48) attaching Front Switch Board Assembly to Front Switch
Board Assembly as necessary for proper switch action.
k. Tighten the two remaining Screws (48) attaching Front Switch Board Assembly to Front Switch
1. Recheck all switch rotors for smooth, free switch action and readjust Front Switch Assembly as
necessary.
4. Assembly of RESOLUTION BW switch:
a. Place Coupler Hub (54) on Frequency Span Shaft (9) with pin facing up (away from Front Switch
Assembly). Do not tighten Coupler Hub at this time.
b. Center Bandwidth Detent (52) over Coupler Hub (54) with stop tab towards top of Front Switch
Assembly, and fasten to Front Switch Assembly using two Studs (53).
c. If Drive Hub (15) has been removed or loosened from Bandwidth Shaft (55), refer to Figure 8-7B for
proper adjustment. Lightly grease narrow end of Bandwidth Shaft (55) and detent holes on Band-
width Detent (52). Insert Bandwidth Shaft (55) through Frequency Span Shaft (9).
d. Inspect RESOLUTION BW Rotor (56). Roll Pins (12) should be positioned in hole 16 and hole 17 as
shown in Figure 8-8E. Check that Springs (23) and Ball Bearings (10) are in position.
e. Place RESOLUTION BW Rotor (56) onto Bandwidth Shaft (55). Position RESOLUTION BW
Rotor assembly so that stop tab does not fall within small span between Roll Pins (12).
f. Clean contact fingers on RESOLUTION BW Rotor and switch traces on Bandwidth Switch Board
(59) using lint-free cloth and isopropyl alcohol/distilled water mixture.
g. Use a 1/4-inch nut driver to fasten Bandwidth Switch Board (59) to Front Switch Assembly with two
Hex Nuts (20). End of Bandwidth Shaft (55) must not bind against hole in board. Align MANUAL
SWEEP Shaft (22) with MANUAL SWEEP Potentiometer (58) by turning MANUAL SWEEP
knob clockwise until shaft engages with MANUAL SWEEP Potentiometer.
Depth of MANUAL SWEEP Shaft (22) can be adjusted if necessary by care-
fully tapping SWEEP TlMElDlV Shaft (24) farther into the white plastic rotor.
h. Turn Front Switch Assembly over and remove FREQ SPAN/DIV knob using a no. 4 hex wrench.
LUTION BW knobs.
NOTE
SERVICE
831