Philips HeartStart XL - Energy Select Switch; Printing Functions; Battery;Power Functions

System Functional Descriptions
6-12 Theory of Operation
Energy Select Switch
The Energy Select Switch selects operation in either AED Mode or
Manual Mode.
In Manual Mode, energy selection is made by rotating the Energy Select
Switch to the appropriate position. The Energy Select Switch signals pass
through the Keyscan PCA and then on to the Control PCA via a large ribbon
cable. The Control PCA then interacts with the other parts of the system as
needed to respond to the setting of the Energy Select Switch.
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
information to the Control PCA. The Control PCA adjusts drive voltage to
the printhead (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, and the Control PCA generates the
appropriate screen message and tones to alert the user.
Battery/Power Functions
Refer to Figure 6-3 on page 6-14 and Figure 6-4 on page 6-15 for the
following descriptions.
Power for charging the battery and running the unit is supplied via the Power
Supply. The M4735A uses approximately 400 - 650 uA of 12 V DC when
powered off to maintain configuration settings, system clock, etc. When
powered on in Monitoring Mode, the unit consumes approximately
500 - 700 mA.
Contacts/Battery Type
The battery mates with contacts on the Battery PCA. Power from the battery
flows through the Main Fuse on the Battery PCA, and then through separate
wires to the Power PCA for distribution to the rest of the unit.