HP 1100AHP - Manual (Page 48)

46 Functional Overview C4224-90962
Power system on ECU
The AC, DC, and high-voltage power supply circuits are all contained within the ECU.
AC power distribution
The AC power circuitry supplies AC voltage whenever the power cord is connected to the AC
power source. AC voltage is distributed to the DC power supply circuitry and to the AC driver
circuitry, which controls AC voltage to the fusing assembly's heating element.
DC power distribution
The DC power distribution circuitry, located on the ECU, distributes +3.3 V DC, +5 V DC and
+24 V DC as follows:
Overcurrent/overvoltage
There are two overvoltage devices in this printer:
• Fuse F101 provides overcurrent protection for the fusing system circuitry. To check or
replace the fuse requires the removal of the ECU. Fuse F102 (found only on 110V units)
provides overcurrent protection to the printer DC power supply circuitry.
• In addition, the +24V DC, +3.3 V DC, and +5V DC power circuitry contains an
overcurrent protection circuit which automatically shuts off the output voltage when an
overcurrent condition occurs due to a short or abnormal voltage on the load side.
High-voltage power distribution
The high-voltage power supply PCA applies an overlap of DC and AC voltage to the primary
charging roller and the developing roller. This circuit also applies a positive or negative DC
voltage to the transfer roller according to the instructions from the ECU.
Table 3-1. DC power distribution
+3.3 V DC Formatter
Laser/Beam Detect Circuitry ECU
+5 V DC: Formatter
Photosensors
ECU
Laser/Beam Detect Circuitry
+24 V DC: Motor
Laser Scanner Motor
Document Scanner Motor
Solenoid
Formatter
+24VA DC: High Voltage Power Supply