Control Board; Power/ Output Board; The User/Display Board; Printer Module - Somatics THYMATRON System IV Service Manual

volume control and is only active after the end of the treatment and until the
START/STOP button is pressed.
The two output monitors are identical duplicates of each other. They monitor the output
during the treatment and if the output charge value exceeds the preset by 15% they shut
off the treatment delivery by releasing the relay as well as blocking the treatment pulses
and they also sound the alarm and activate the "Safety monitor LED".
4.2.

Control board

The control board contains the CPU and other digital circuitry such as DRAM and
EPROM. A static memory chip combined with battery backed clock is used for real time
clock and for parameter backup. Two crystal oscillators provides timing signals, one is
running at 16.67 MHz and is used for 32 bit 68306 CPU clock and for the safety
monitoring and peripheral PIC microcontrollers, the other is an 3.58 MHz and is used for
timing of the pulses and data collection. All address and data lines are buffered.
4.3.

Power/ Output board

The power/output board contains DC power supplies and the ECT output drive.
There are three power supplies.
a. The 5V power supply provides power for all digital and analog circuitry and for the
digital circuitry on the printer.
b. The +24V power supply provides power for the positive half of the ECT output drivers
and for motor and thermal head of the printer.
c. The -24V power supply provides power for the negative half of the ECT output drivers.
Each supply is individually protected by a fuse.
The ECT output section contains the constant current supply and two power drivers. One
driver controls positive pulses while the other driver controls negative pulses. The ECT
output is voltage boosted, as well as isolated, by T103 transformer
4.4.

The User/Display board

The User/Display board contains all user displays and controls. One display is an 8
character alphanumeric and the other is 4 character alphanumeric. Both displays are driven
by one microcontroller which is connected to the main bus by its slave port. It also
controls the input dials and buttons consisting of Impedance, Treat, Start/Stop and Alarm
Test. The two dials are both optical encoders, one controlling the Flexdial (setting of the
parameters) and the other controls the energy level.
4.4.

Printer module

The 100 mm thermal printer is used to record up to 4 channels of patient data as well as
time and other alphanumeric data. It uses 100mm fanfold thermal paper. It is connected by
a bi-directional parallel bus to the main processor. It is programmed to be able to run at
three speeds: 5mm, 25mm and 50 mm/sec. The 5 V power for the digital circuitry and the
24 V power for the thermal head and the motor are supplied by the power board.
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REV: 3.1 09/15/2015