DEC DEClaser 5100, Service Manual

Page: 58 / 274

2.5 HVPSA
2.5 HVPSA
Figure 2–11 shows the high-voltage bias circuits that are used by the
xerographic processes discussed in Section 2.3. Not shown in Figure 2–11 is
the HVPSA/fuser interconnect that makes connection to the DC control board.
Figure 2–12 photographically shows the locations of the high-voltage terminals.
The HVPSA communicates with the DC control board through the serial
SL02
and
SLI2
signal lines. IC402 is a communication gate array that provides
two-channel serial interface to IC202 on the DC control board.
IC401 is a custom integrated circuit that provides the following:
• The ac bias coupled with dc bias used by the primary and development
processes. The dc component varies according to laser beam intensity
and to the setting of the user assessable density adjustment. The HVPSA
couples this dc component to the development bias.
• The transfer bias switches from negative for cleaning and to positive for
printing.
• The static eliminator removes the residual transfer charge from the paper
sheet.
• TB402 and the contact plate capacitor provide an ac ground path for the
transport entrance guide.
The HVPSA contact plate mechanically connects the HVPSA to the EP-ED
cartridge and contains the transfer roller and static eliminator. The coil
and flat springs of the contact plate press against metal contact pads on the
HVPSA circuit boards. The spring holding pressure comes from the screws and
clips that are used to mount the HVPSA and contact plate.
2–22 Technical Description