Service manual

FO-4700U
FO-47UC
3 – 6
Temperature immediately after temperature control start
The state before
discontinuation of
less than 50˚C
50˚C or more,
100˚C or more
temperature less than 100˚C
control
Mode 1
Mode 1
Mode 2, 3
Mode 1 Mode 2 Mode 3
or Power OFF
The following three different temperature control modes are provided for
the Heater Roller.
1) Mode 1 The temperature is controlled to maintain 105˚C
during standby and 185˚C during printing. If this
mode continues for 45 seconds, it will shift to mode
2.
2) Mode 2 The temperature of the Heat Roller falls gradually
to about 175˚C from about 185˚C. If this mode con-
tinues for 208 seconds, it will shift to mode 3
3) Mode 3 The temperature is controlled to maintain 105˚C
during standby and 175˚C during printing. Unless
an error occurs or an top cover is opened, this
mode is maintained.
10. IMAGE TRANSFER
10-1. Overview
Image transfer is the process of transferring the toner image created on
the PC Drum in the developing process to paper. Roller Image Transfer
is used instead of the Corona Image Transfer as the image transfer
method. In the Roller Image Transfer, there is little generation of ozone
due to corona discharge. Also, there is no blur of toner because the
paper is always pressed by the PC Drum and the Image Transfer Roller.
When cleaning the Image Transfer Roller and before printing, reverse
bias is applied.
Fig. 9
11. FUSING
11-1. Overview
The toner image transferred onto the paper is securely fixed to the pa-
per.
A heat roller system is used as the fusing system. The toner image is
fused by the Heat roller heated by the Heater Lamp, and securely fixed
by the pressure between the Heat Roller and Backup Roller.
A Thermistor (TH1) detects the Heat Roller temperature.
The Thermostat (TS1) contacts open when the temperature becomes
approx. 195˚C and shuts down the power to the Heater Lamp.
11-2. Fusing Temperature Control Circuit
The Thermistor (TH1) detects the surface temperature of the Upper Fus-
ing Roller and inputs that analog voltage into IC2-78. Corresponding to
this data, the Heater Lamp ON/OFF signal is output from IC2-55, caus-
ing the Heater Lamp (H1) to turn ON or OFF to control the fusing tem-
perature.
When the Heater Lamp is not turned OFF even if the Thermistor detects
a high temperature malfunction (if the surface temperature of the Upper
Fusing Roller exceeds 210˚C), the signal from IC2-79 changes from L to
H to turn OFF the Heater Lamp forcibly.
Fig. 12
Fig. 10
Fig. 11
Printer PWB (PWB-A)
IC2
DC5V
DC5V
IC5
78
79
GND
CMPIN
CMPOUT
PO1
GND
24V MAIN
MG
DG
5VMAIN
HEATER ON
FAN
FAN LOCK
H RELAY OFF
HEAT-L
N.C.
HEAT-N
GND
55
2
L
1
3
Q103
H1
TH1
TS1
CN2
CN7
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
1
2
1
2
L H1 : ON
H1 : OFF
H
1
2
3
CN1
CN2
Power Supply PWB
Heater Lamp
Thermostat
Thermistor
H
L
L
PC Drum
PC Drum
Paper
Paper
Image Transfer Roller
Image Transfer Roller
Image Transfer
Bias
Reverse Bias
Discharge Needle
Paper Separator
Paper
Backup Roller
Fusing Entrance Guide
Thermostat (TS1)
Heater Lamp (H1)
Heat Roller
Thermistor (TH1)
Warming-Up
Thermistor detecting temperature
185˚C
175˚C
Temperature (˚C)
105˚C
Mode 1: 45sec Mode 2: 208sec Mode 3
Standby
Printing