4-8. ADJUSTMENT OF PERCUSSION CUTOFF CONTROL. This control, located in the
preamplifier (See figure 1-7) should be readjusted whenever control tube V7 is
replaced. Set expression pedal wide open, both volume tablets to Normal, percussion
tablet ON , and harmonic selector in either position. Play any key in upper half of
upper manual, hold it down at least 5 seconds, and then adjust percussion cut-off
control exactly to the point where the signal becomes inaudible.
4-9. ADJUSTMENT OF INTERMITIENT OR NON-OPERATING KEYS.
4-10. Scratchy, noisy, or silent keys may result from accumulations of dust which
lodge in the contacts. To correct this condition, strike the key 15 to 20 times in a
rapid staccato manner to dislodge the dust particles and to clear the contacts.
4-11. If this procedure does not dislodge the dust particles, adjust the busbar
shifters. (See Rear View of consoles at end of General Descriptions, figure 21 in
Manuals, Pedals, etc., and figures 4-2 & 4-3 below) Busbar shifter A, located behind
the matching transformer, adjusts the busbars associated with the keys of the upper
manual; busbar shifter B adjusts the busbars associated with the keys of the lower
manual; busbar shifter C adjusts the busbars associated with the pedal keyboard.
4-12. Turn the proper busbar shifter about two turns in either direction. This
operation permits the key contacts to strike a new position on the busbar and should
free all contacts of accumulated dust particles.
4-13. If, in extremely stubborn cases, the procedure above does not dislodge the
dust particles, use a board to depress one octave of notes (7 white and 5 black
keys) and then adjust the bus bar shifters while holding the keys down.*
* - this procedure has been deemed inappropriate in recent years and could cause damage to
the key contacts - JL
13
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