Power Supplies; The Low Voltage Power Supply (Lvps); The High Voltage Power Supply (Hvps) - Xerox 4400DT - Phaser B/W Laser Printer Service Manual

Power Supplies

The Low Voltage Power Supply (LVPS)

The LVPS uses a resonance-type switching regulator. The LVPS supplies +24 VDC,
+5 VDC, +3.3 VDC.
The LVPS has built-in overcurrent protection. If an excessive current begins to flow
the DC supplies are shut down. Switch the power supply OFF for 5 minutes, then ON
again to reset the circuit after an overcurrent shutdown.
The LVPS also supplies AC power to the Heat Rod. A circuit, controlled by the Heat
ON signal from the Engine Logic Board, switches power to the Heat Rod.
LVPS Block Schematic Diagram

The High Voltage Power Supply (HVPS)

The HVPS supplies high voltages for the Bias Charge Roller (BCS), Transfer Roller
(TR), Drum Bias (DB), and Detack Saw (DTS). The HVPS receives +24 VDC input
from the LVPS, along with nine control signals from the Engine Logic Board.
The HVPS has built-in overcurrent protection. If an excessive current begins to flow
in any of the four power supplies, all of the supplies are shut down. Switch the power
supply OFF, then ON again to reset the circuit after an overcurrent shutdown.
Phaser 4400 Laser Printer Service Manual 8-23