Moe - GE MAC 5000 Service Manual

Moe

Revision B
Equipment Overview: Theory of Operation
Similarly, if the servo error variable saturates at "off" for more than a
predetermined time, it is assumed that the someone is pulling on the
paper with a force that exceeds the paper drive system torque, and as a
result paper speed has been pulled out of regulation. This condition is
reported as a Paper Pull Error.
Cue Hole Sensor
Cue and out-of-paper conditions are sensed via the thermal print head's
integral optical cue sensor. Larry monitors the cue sensor's logic output.
Cue Hole Detection
Larry monitors the output of the cue sensor to detect the presence or
absence of paper under the sensor, and hence the absence or presence of
cue holes.
Paper Tracking Fault Detection
Larry monitors the cue sensor for abnormally long paper travel without
encountering a cue hole. This condition is reported as a Paper Fault.
Paper Out Detection
Larry reports excessive paper travel without sensing paper as a paper
out condition.
Analog Inputs
Larry digitizes four analog inputs at eight bits resolution each. Two
inputs handle external analog signals, such as those produced by
ergometers or analog output blood pressure monitors. Thermal printhead
temperature is measured for use in compensating strobe pulse width to
maintain constant print density over a wide range of thermal printhead
temperatures. The output of the thermal printhead pixel test hardware
is also digitized to allow the resistance measurements on individual print
elements.
Moe is responsible for controlling and monitoring the battery, power
supplies, on/off key, system reset and related functions. Moe runs
continuously from +3V-C, even in the absence of AC power. This
continuous operation is necessary for Moe to accurately monitor the
battery state of charge and detect power key presses.
System Startup
When the system is off and the user presses the power key, Moe begins
the startup sequence. If the battery contains sufficient charge, or if AC
power is applied, the main CPU board power supplies (+3V-M and +5V-
M) are enabled and after a suitable stabilization period SYSRESET* is
released. Moe then keeps tabs on the system via a software watchdog
that must be serviced by specific BBus activity from the ATMEL CPU.
Moe himself is monitored by a self contained MAX823 watchdog timer /
brownout detector. Moe must constantly toggle the MAX823 watchdog
input pin or suffer the consequences.
MAC™ 5000 resting ECG analysis system
2024917-010
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