Power Supply; Vmain And Vin; Battery Charger And Battery Sensor - HP PageWriter XL M1705B Service Manual

Power Supply
The power supply's basic tasks are to charge the battery when the
cardiograph is connected to AC power, provide +5 volts to the
system logic, provide power to the printer, and provide operating
voltage to the patient module. These are the circuits that make up
the power supply:
-\
n
Battery Charger and Battery Sensor
w 5 Volt Regulator
n
+5 Overvoltage/Undervoltage Sensor
H Printer Switch
H Battery Switch
n
ACON Detector
H +5 Backup Supply and Low Battery Disconnect
n
+5-to-Backup Switchover
n
Patient Module Voltage Regulator
Note .I
t?
Although the power supply circuits are discussed separately from the
.
CPU assembly, they are all physically located on the CPU assembly
except for the battery, the transformer, and the diode assembly cable,
which includes the rectifier and filter capacitors.
Figure 5-10 shows how these circuits connect to each other and to
other parts of the system.
VMAIN and VIN
VMAIN connects to the CPU assembly at JG and 57. It is the
unregulated, rectified AC that comes from the main transformer
and bridge rectifier assembly. After passing through a fuse, VMAIN
becomes VIN, which supplies power to the +5 volt regulator, the
patient module regulator, and the preview display assembly.
5-16 Theory of Operation