Technical Description; Operation Of Each Pwb; Cpu Motor Control - Hammond Leslie 3300 P Service Manual

9. TECHNICAL DESCRIPTION

1. General
This unit corresponds with the Leslie 11-pin Input, the 8-pin Input and the LINE Input.
It has 1 channel (the Rotary Channel only) and two very powerful Amplifiers (220W + 80W).
The Treble Horn Rotor and the Bass Drum Rotor are driven by the respective DC
Servo-Motors, The built-in Tube allows natural distortion/overdrive effects without adding excess
Volume similar to the performance of Leslie models 122 and 147.
The Slow/Fast speeds and Rise/Fall times are user-adjustable.
The PWB's consist of:
a. Pre-Amp & Tube Drive PWB (PAH-74B)
b. CPU Motor Control PWB (CTH-37A)
c. Power Amplifier & Power Supply PWB (PWH-74C)
d. Motor Driver PWB (LGH-43A)

2. Operation of Each PWB

A. PREAMP & TUBE DRIVE (PAH-74B)
This PWB consists of the Pre-Amp, the Tube Drive section and the Filter section.
The signals, input from the Leslie 11-pin Connector Pin (1), are sent through J303-5
and are mixed with the input of the Line-In Jack JK-3 and the Leslie 8-pin Connector CTH-37A
JK-2 Pin (1), then the gain is adjusted at the Sub-Pre-Amp IC1A and VR1, and are supplied to
the input of the V1 through the Tube ON/OFF switch of the VR1.
The V1 is the circuit for the Tube-Overdrive. With this, the user can set the Overdrive to
the VR1 Drive Level and the VR3 Tube Mode Volume from softer distortion to hard distortion as
required.
The Overdrive can be switched OFF, only by turning the VR1 Drive Lever to the leftmost position, i.e.
"Tube OFF", which automatically switches ON the direct input to IC1B.
Next, the signals, sent through the Master VR2, can be controlled by the Bass (60Hz), the MID (1.7kHz)
and the Treble (10kHz) by ±10dB I using the 3 band Equalizer C2.
Finally, the signals, divided by the HPF and the LPF of the IC3, are sent to the PWH-74C by J302.
Also the signals for the Sub-Woofer ( below 125Hz) and those for the Line-Out are sent to the JK4
through the VR8.
B. CPU MOTOR CONTROL (CTH-37A)
This PWB consists of the Voltage Generating circuit for the Motor Control, the CPU circuit for
controlling and the Power IC circuit.
The U1 CY8C24423A is a 1-chip CPU, containing the built-in CPU of the Clock circuit, the
ROM, RAM, and Analog Interface circuits. This most advanced Controller CPU is operated by the
Power Supply of only +5V. It monitors the Rotation Pulses (J205-1, 2) of the Horn side and the Drum
side Motors, emits the Brake Pulse to the LGH-43A circuit, and automatically controls the Rise Time.
It also monitors the Slow/Fast Control signals received via the Leslie 11-pin and 8-pin and controls the
motor rotation with "Last-Action-Priority" by adding the Foot-Switch operation.
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