5-31. MANUAL CHASSIS ASSEMBLY.
5-32. The 9 contact springs on each key are connected by resistance wires to the
proper terminals on the terminal strip and carry the harmonics of the particular
note with which they are associated. The resistance wires avoid overloading of the
generators and thus allow each generator to be used independently to feed a number
of key circuits. All key contacts are alive at all times. When a playing key is
depressed, its 9 frequencies are impressed on the 9 bus bars of the manual. No wires
are connected to these bus bars; a preset or adjust key must be depressed to
complete the circuit. (See console schematic) Each preset or adjust key is provided
with 9 contacts identical to those on the playing keys and is further provided with
a locking and tripping mechanism, the purpose of which is to permit only 1 preset or
adjust key to be in operation at a time. The cancel key releases a depressed preset
or adjust key; this cancel key has no contacts.
5-33. Flexible wires connect the 9 contacts of each adjust key (A# and B) to the 9
drawbars controlled by the key. The wires are color-coded for identification. Each
drawbar makes contact (according to the stop position to which it is drawn) with any
one of 9 busbars connected to taps on the mixing transformer. (See console
schematic). The bus bars correspond to different intensities of sound.
5-34. The 9 preset keys ( C# to A ) are connected by flexible leads to the preset
panel in the back of the console. (See Rear Views of consoles at end of General
Descriptions section). The preset panel consists of 2 sets of 9 busbars which
correspond to those in the drawbar assembly and which are connected to the same taps
on the matching transformers.
5-35. The matching transformers are mounted on the manual chassis assembly as shown
in Rear Views of consoles at end of the General Descriptions section. Shielded leads
carry the signals from the secondaries of these transformers to the preamplifier.
5-36. PEDAL SWITCH ASSEMBLY. The pedal switch assembly is similar in operation to
the manual chassis assembly (reference paragraphs 5-31 to 5-35 inclusive); the pedal
switch assembly, however, contains only 4 bus bars instead of 9. A flat spring at
the end of each pedal of the detachable pedal clavier depresses a small plunger, as
shown in figure 5,(p.6) of the Manuals, Pedals, etc. section, on the pedal switch
assembly and actuates a double set of contact springs, thus making eight contacts
available for each note the pedal contact springs are connected by decoupling
resistance wires to terminals. A cable connects these terminals through a wiring
tube to the proper terminals on the main tone generator strip. The pedal switch bus
bars are connected, by means of four colored wires, through a filter reactor
and resistor network to the pedal drawbars. (See figure 5-9 on next page.) The
reactor and resistors filter out undesirable higher harmonics and serve to balance
the pedal tones.
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