CHATTANOOGA
GROUP INC.
JP3 supplies power to the fan and JP6 is for the beeper.
The Stim Board
The Stim Board’s function is to generate various output waveforms
under the direction of the Control Board. Due to the variety of waveforms
commonly used in electrotherapy, there are different waveform generators on
the board, all controlled by a common Digital Signal Processor (DSP).
•
The Sine Wave Generators
There are two of these on each Stim Board, one for channel 1 and the
other for channel 2. Each is identical except for their connections to the
output jacks. Under control of the DSP, Programmable Array Logic (PAL)
devices generate a driving signal which is fed to an amplifier. The output
amplitude of the amplifier is determined by a programmable power supply,
also controlled by the DSP. The resulting output is filtered and routed by
relays to the appropriate connector on the board.
These same generators are used to develop the VMS, or Biphasic
output, the Premod output, the Interferential output and the Russian output.
•
The Hi-Volt Generator
The Hi-Volt output is only available from channel 2 of the unit. Under
control of the DSP, timing information is generated by a PAL. This is used to
control the charging and discharging of a transformer. The discharges are
routed through relays to obtain the proper polarity and connect them to the
proper output connector on the board.
JP2 on the Stim Board determines whether the board operates as
channels 1&2 or 3&4 on a CPS 400. This jumper must be set for channels
1&2 for the unit to operate properly. See the board drawing in the Signal Lists
section for jumper configuration.
The Ultrasound Board
The Ultrasound Board uses a Phase Locked Loop (PLL) that is set by a
PAL based on control by the Control Board to generate a stable high
frequency signal. This signal is used to drive an amplifier whose output is
filtered and drives the transducer. The amplitude of the amplifier output is
determined by its programmable power supply. Other circuitry monitors the
temperature of the transducer as well as voltage and current of the drive to
the transducer.
The Ultrasound Board is controlled by signals from connector JP5 of
the Control Board that are carried through a 40 conductor cable to J1 on the
Ultrasound Board. The signals consist of address and data lines as well as
handshake lines. There are also signals for turning off the power supplies on
the Ultrasound Board when it is not generating output.
The power for the Ultrasound Board is through J2. Connector J3 is the
output of the Ultrasound Board which ultimately drives the transducer in the
applicator.
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Legend Series Service Manual
