Hammond Organ Service Manual - Early Models (A,B ... - Audiofanzine

t
MhIFTES
PINS
4 ft ^ ^ «
ON BEAR
i
SIGNAL
PICKUPS
FOR PEDAL SOLO
PED*L
SWITCH
ACTUATOR
DOWN STOP
f ELT
FIGURE 21
MODEL RT. RT-2. RT-3 and D-1 00
Pedal Switch Assembly
The pedal switch (shown in Figure 21) is similar in internal construction to the
manuals (Figure 2Z), Each of the 32 pedals actuates a set of contact springs,
making nine contacts available for each note. Each note consists of a fundamental
and a number of harmonics, no sub-harmonics being used. The pedal
contact springs are connected to terminals by resistance wires similar to those
used in the manual assembly, and a cable connects these terminals to the proper
terminals on the generator terminal strip. Only seven contacts are used
for the mechanical generator notes, the other two contacts are used by the pedal
solo unit as explained later in this book.
Four colored wires carry the pedal tones from the busbars to the pedal drawbars.
The wires are connected first to a resistor panel on the back of the manual
assembly. A small choke coil and resistor nnounted on the manual assembly are
wired to the lower drawbar (see Figure 23) and serve to filter out any higher
harmonics or transients which might be present in the lower pedal frequencies.
Figure 24 is a wirmg chart for the pedals, showing the frequency numbers appear
ing on each pedal contact.
2-22A