Hammond Organ L-100 Series, Руководство по обслуживанию

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Page 13
1–6 HARMONIC DRAWBARS
The left group of seven harmonic draw bars ( Figure 1–9 ) is
associated with the lower manual, and the right group of nine draw
bars controls the upper manual. By sliding these drawbars in and
out, the organ is able to mix the fundamental and harmonics (or
overtones) in various proportions. The distance a bar is pulled
out determines the strength of the corresponding harmonic; and
if a drawbar is set all the way in, the harmonic it repre sents is not
present in the mixture. Neither manual will play unless one of its
drawbars is pulled out at least part of the way with the drawbar tab
pressed, or a preset tab is pressed.
Figure 1–9: Drawbars & Control Tabs (Partial View)
The drawbars slide over 17 busbars, representing intensity levels.
As the drawbar moves, its contact is touching some busbar at all
times, and therefore there is a smooth change in volume of that
harmonic.
These busbars extend the length of the draw bar assembly, and
are connected to the low impedance primary of a matching
transformer. Signals from the high impedance secondary of this
transformer go to the preamplifier input. The matching transformer
is localed within the preampli fier chassis.
1–7 PEDAL DRAWBAR
The center drawbar adjusts the volume of the pedals. Its operation
is similar to that of a manual drawbar.
1–8 PEDAL KEYBOARD
The 13 playing pedals are operated by the left foot and are con-
nected to the lowest 13 frequencies of the generator. Like the
manuals, they have light and dark keys arranged in the standard
octave pattern.
Figure 1–10 identifies the pedals and shows the
generator frequency number associated with each. A single
contact on each pedal closes when the pedal is pressed, thereby
allowing the correct generator frequency to reach the amplifier.
Figure 1–10: Pedal Keyboard