Ricoh FW 810, Service Manual, Page: 51 / 170

5.5 T/S CORONA CIRCUIT
The T/S power pack is powered by +24 volts (Va) from the dc power supply.
The dc/dc converters and dc/ac inverter change the +24 volts to the high
voltages used by the transfer and separation coronas.
The main board (PCB1) turns on the transfer corona by dropping CN107-B12
(T.Trig) from 24 volts to 0 volt. This turns on the dc/dc converter, which
applies a high voltage of approximately --5.0 kV to the transfer corona wire.
The main board turns on the separation corona by dropping CN107-B13
(S.Trig) to 0 volt. The dc/dc converter and dc/ac inverter circuits then apply
approximately ac 4.0 kV and --200 V to the separation corona wires.
Normally, T.Sel is not used. However, if the user presses the Auto Image
Density key for longer than 3 seconds, the CPU uses both T.Trig and T.Sel to
turn on the transfer corona. This increases the transfer corona current from
150
µ
A (the normal value) to 250
µ
A. The higher transfer current may be
useful under high humidity conditions (When the higher transfer corona
current is selected, the manual ID display function inverts.)
-5.0 kV
AC 4.0 kV
[P2]
[PCB1]
CN1-2
+24 (Va)
DC/DC
Converter
DC/AC
Inverter
DC/DC
Converter
-6
-B11
-5
-B13
-4
-A13
-3
-B12
24
24
24
T. Trig
T. Sel
S. Trig
Not Used
CN107 CN1
CN1-1
A. GND
DC -200 V
T
S
6 January 1990
2-29