Canon NP2120 Service Manual page 86

C. Fixing Assembly and Deliv-
ery Assembly
1. Controllfng theFfxfng RollerTemperature
The upper and lower rollers of the fixing assem-
bly and the delivery roller of the delivery assembly
are driven by the main motor (Mi).
The upper roller has a built-in heater (Hl ,90 W),
which heats the roller.
The DC controller monitors the surface tempera-
The specifics of the control are as follows:
a. NP2020
control temperature
(standby/copying) _..____._.......................... 170°C
control temperature (pre-heat) ._................ 140'
control temperature (standbylcopying) 150°C
control temperature (pre-heat) 140"
b. NP2120
control temperature (standby/
control temperature (standby/pre-heat) . ..15O"C
control temperature (copying) 1
To prevent lowering of the surface temperate
of the upper rollerduring continuous copying. the
control is switched as follows when copying lasts
about 15 seconds.
a. NP2020
175°C control
155°C control
165°C control
Note:
Small-size papers include A4, 85, LTR, and
LGL
3-44
b. NP2120
pick-up is from the cassette,
switched to 185°C control; otherwise. 170°C is
switched to 175%
pick-up is from the multifeeder,
than A4R is used, 170°C is switched to 175°C
control
cassette,
switched to 170°C control: otherwise, 150°C is
switched to 160°C
multifeeder,
to 175°C control; otherwise, if paper shorter
than A4R is used. 165°C control is used as is
The copier is equipped with the following four
types (or three types if NP2020) of protection
mechanism to prevent the fixing heater from
going ON at the wrong timing.
The microprocessor monitors the voltage of
TH1 ; when it finds an error, it issues EOOO or
155°C
If the voltage of TH1 lowers to about 1 .O V or
lower (220°C equivalent), the error detection
6 5 "
regardless of the output of the microprocessor.
the power to the fixing heater.
If the SSR ON detection PCB detects the acti-
to the DC controller PCB. In response, the DC
controller PCB compares the output timing of
the HTRD signa1 and the SSR ON timing,
issuing E004 upon identification of an error
(applies to NP2120 only: see the SERVICE
HANDBOOK).
Note:
Do not use the thermal switch (TS) once it has
opened; it cannot serve fts purpose unless
C A N O N NPZl20/2MO KV.1 DEC. 1992 PAINTED IN JAPAN IIMPAIME AU JAPONI