HP 220 - Manual (Page 64)

5Ć32 Functional Overview C3187Ć90000
Power Supply
An autoĆranging power supply is located in the electronics enclosure. It accepts and
automatically adjusts to an ac input of 90 V through 264 V and produces regulated voltages of
+5 V, +12 V and -12 V, and an unregulated +24 V. These voltages are used as follows:
Voltage Use
+24 V Motor drivers and voltage regulator on the main PCA.
(Regulated +20 V for cartridge circuits on the carriage PCA).
+12 V Fan power and RS-232 driver.
–12 V RS-232 driver.
+5 V IC power and sensors.
The primary portion of the supply contains fusing and input protection circuitry, line filters,
and a rectifier. The primary output is converted to a pulseĆwidthĆmodulated (PWM),
unidirectional current by a flyback dcĆtoĆdc converter.
The secondary portion of the power supply contains the four secondary windings of the
transformer that convert the PWM current in the primary to four ac voltages, which are
rectified to the +5 V, +12 V, -12 V and +24 V dc voltages required by the plotter. Standard
+12 V and -12 V regulators are included in the secondary portion of the power supply.
The primary side of the power supply contains rectified line voltage
that can be lethal when touched even if the ON/OFF switch is OFF.
Remove the power plug before working inside the electronics
enclosure. Also, leave the powerĆsupply insulating door closed when
you need to work on the main PCA only.
W F R N I N G