Epson EPL-N4000 - Page 91

EPSON EPL-N4000/EPL-N4000+ Chapter 2 Operating Principles
Rev.B 77

Low Volta
g
e Power Supply (LVPS)
Takes filtered AC volta
g
e and converts it into re
g
ulated +24VDC
and +5VDC.

The LVPS contains
overcurrent protection circuits
. If an
excessive current be
g
ins to flow throu
g
h any of the components
supplied by the LVPS, the LVPS immediately shuts down all low
volta
g
e output. To reset the LVPS after an overcurrent
shutdown; switch off the printer, wait a few minutes, then switch
on the printer.

The LVPS contains
open circuit protection circuits
. If the
LVPS detects that a circuit is open for lon
g
er than one minute,
the LVPS slowly decreases the LVPS output until the output is
zero. To reset the LVPS after an open circuit shutdown; switch
off the printer, wait a few minutes, then switch on the printer.

The LVPS contains a low +24VDC output protection circuit. If
the LVPS detects the +24VDC output droppin
g
below +15VDC,
the LVPS slowly decreases the +24VDC LVPS output until the
output is zero.
LVPS Fan:
A +24VDC fan that cools the LVPS PWB.

Machine Control Unit (MCU PWB)
Takes the +24VDC and +5VDC
g
enerated by the LVPS and
distributes them to the various components throu
g
h out the printer,
includin
g
+24VDC to the Hi
g
h Volta
g
e Power Supply (HVPS).

Interlock Switches SW1 and SW2:
Used as a safety measure.
The main interlock circuit for this printer is actually two
separated switches wired in series with the MCU PWB. When
the EP Cartrid
g
e is in place, Interlock Switch SW1 is closed.
When the Left Front Cover is closed, Interlock Switch SW2 is
closed. With both switches closed, the circuit is complete and
the MCU PWB sends +24VDC to the HVPS and other printer
components.
If either SW1 is open (the EP Cartrid
g
e removed) or SW2 is open (the
Left Front Cover is open) the MCU PWB cuts all +24VDC output from
the MCU PWB.

Hi
g
h Volta
g
e Power Supply (HVPS)
Takes the +24VDC received from the MCU PWB and converts it to
the hi
g
h volta
g
es that are required by the printer xero
g
raphic
components.

The HVPS contains
overcurrent protection circuits.
If an
excessive current be
g
ins to flow throu
g
h any of the xero
g
raphic
components, the HVPS immediately shuts down all hi
g
h volta
g
e
output. To reset the HVPS after an overcurrent shutdown; switch
off the printer, wait a few minutes, then switch on the printer.
W ARNING
Even though the interlock switches cut the +24VDC
output from the MCU PWB, +24VDC output from the
LVPS is still present throughout the printer as well as
110VAC line voltage along the AC paths in the
printer.