9. Connect ohmmeter to common and m1n1mum resistance terminals
of potentiometer (6). Ohmmeter should read "0" resistance.
10. Adjust potentiometer (6) to 130 ohms (±120 ohms).
11. Place nylon washer (29), gear (30), and hub (31) on shaft of
attenuator (7). Tighten two set screws (32) in hub. Monitor
ohmmeter to prevent inadvertent change in potentiometer
setting.
Screw holes in gear must be aligned horizon
tally. Holes in hub must be aligned just above
center line of VAR TONE Volume knob or the plug
in the Front Panel (see Figure 6-10).
12. Place FINE Adjust knob (33) in position, with machined slot
over gear (2). Insert 0.005 inch shimstock (Appendix C)
between knob (33) and hub (31). Rotate knob fully ccw so end
of slot contacts gear and install two flat head screws (34)
(Figure 6-10). Monitor ohmmeter to prevent accidental change
in potentiometer setting. Remove shimstock.
�21�
Spacing with shimstock is essential to prevent
excessive drag of knob (33) on hub (31).
13. Rotate FINE Adjust knob (33) fully cw and back ccw. Ohmmeter
should return to its original reading of betwe�n 10 and
250 ohms.
14. Position cursor (35) on FINE Adjust knob (33) and install two
flat head screws (36).
15. To install dial (37), proceed as follows:
a. Install knob (38) on attenuator (7) shaft and tighten set
screws (39).
b. Rotate attenuator knob (38) ccw one detent. Loosen set
screws (39) and remove knob.
��
The attenuator must be free to stop itself,
centered in the detent. Rotating the shaft
with pliers could overrun the detent center
and cause misalignment of the dial.
c. Position dial (37) with -30 dB index directly over cursor
(35) index. Install two round head screws (40).
6-27
Summary of Contents for FM/AM-500
Page 152: ...DETAIL A 11 Figure 6 6 Dual vco 6 14 01 Assembl Y ...
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