MODEL8559A

SERVICE

14.Disconnect 10-conductor ribbon cable connected to DPM Driver Assembly AlA2. Remove screw holding DPM Display Assembly AlAl to diecast. DPM window will fall out.

15.Use a 5/16-inch nut driver to remove the two nuts attaching front panel to Front Switch Diecast (1). Remove front panel from Front Switch Diecast.

16.Place Front Switch Assembly A2 on flat working surface with remaining knobs face-down and lock mechanism facing you. Prop sides of switch assembly to allow knobs and shafts to clear working surface (be careful not to scratch front panel enamel).

17.Remove screw and washer attaching Attenuator Bracket (49) to Front Switch Diecast (1). Remove RF Input Attenuator Assembly A3 from Front Switch Assembly A2.

18.Disassembly of REFERENCE LEVEL Switch:

Cut tiewrap holding REF LEVEL FINE wires to rear switch board.

Remove the three screws (48) attaching Ref Level Fine Pot Plate (68) to Standoffs (62).

Remove Index Disc Locator and Ref Level Fine assembly (30, 31, and 64 through 69) from Front Switch Assembly A2 (set to one side, without detaching wires).

Remove three standoffs (62) used to support Ref Level Fine Pot Plate (68). Use a no. 6 hex wrench to loosen the two set screws on Miter Gear (51) attached to Attenuator Shaft Assembly (18); then remove Miter Gear from shaft.

Use a no. 4 hex wrench to loosen Rotating Lockout (63) attached to Ref Level Shaft (6), and remove lockout from shaft. Remove Ref Level Detent (61) from Front Switch Assembly A2. Be careful to keep Ball Bearing (10) and Spring (11) with Ref Level Rotor (60).

Remove the three Studs (53) used to support Ref Level Detent (61).

Use a no. 4 hex wrench to loosen the two set screws on front Anticrush Drive Hub Assembly (7) (between Front Switch Board M A 1 and Front Switch Diecast (1) on Ref Level Shaft (6); accessible from side of Front Switch Assembly). Remove Ref Level Rotor (60) and Ref Level Shaft (6) with rear Anticrush Drive Hub Assembly (7) still attached.

NOTE

Rear Anticrush Drive Hub Assembly (7) on Ref Level Shaft (6) is preset at 9.525 mm (0.3 in.) from end of shaft (see Figure 8-7A). Do not remove drive hub unless necessary for repair.

19.Disassembly of RESOLUTION BW Switch.

a.Remove Retaining Clip (21) from RESOLUTION BW Shaft (55).

b.Use a 1/4-inch Nut Driver to remove two Hex Nuts (20) attaching Bandwith Switch Board (59) to Front Switch Assembly, and set board to one side (without detaching wires).

c.Remove Bandwidth Rotor (56). Be careful to keep Ball Bearings (10) and Springs (23) with rotor.

d.Remove Bandwidth Shaft (55), with rear Drive Hub (15) still attached, from Front Switch Assembly.

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