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System Functional Descriptions
Printing Functions
All printing data are handled by the Control PCA. Waveforms, graphics,
numeric values, and messages are all generated and formatted by the Control
PCA, using either data it has or data it receives from other parts of the unit.
This data is then passed to the Printer via the printer ribbon cable.
Contrast
The printing contrast is controlled automatically by the Printer itself. The
printhead senses its own temperature and impedance, and passes that informa-
tion to the Control PCA. The Control PCA adjusts drive voltage to the print-
head (and thus contrast) based on these readings and on battery voltage.
Out of paper/door open
The printer also incorporates an optical sensor that detects when there is no
paper left, or when the printer door is open. The information is passed to the
Control PCA via the printer ribbon cable; the Control PCA generates the
appropriate screen message and tones to alert the user.
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M3500B/M5500B Service Manual
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