HP LaserJet Pro P1100 - Page 34

Low-voltage power supply
The low-voltage power supply (LVPS) converts ac input voltage to dc voltage. The LVPS has two fuses
on the PCA. The LVPS 24 V output is interrupted to the fuser and the high-voltage power supply if the
cartridge-door interlock switch (SW501) is in the off position (cover open).
WARNING! The product power switch only interrupts dc voltage from the LVPS. The ac voltage is
present in the product when the power cord is plugged into a power receptacle and the power switch is
in the off position. You must unplug the product power cord before servicing the product.
Figure 1-10 Low-voltage power supply (LVPS)
BSTSIG
FREQSNS
AC input
DC controller
+24V ON/OFF
circuit
+5V
+24U
+3.3V ON/OFF
circuit
+24V
24VON
+24P
+3.3U
+3.3V
+5R
+3.3R
Fuse (FU201)
Fuse (FU101)
Protection
circuit
Low-voltage power supply
+5V
generation
circuit
Fuser unit
Cartridge-door switch
(SW501)
Engine controller
Power switch
(SW502)
+3.3V
generation
circuit
+24V
generation
circuit
High-voltage
power supply
Frequency
detection circuit
(220-240V model only)
Rectifying
circuit
Formatter
+3.3UON
+3.3VON
16 Chapter 1 Theory of operation ENWW