Canon NP2120 Service Manual page 90

AND TIMING
(NP21 20)
1. Outline
The error detection circuit is built into the DC
controller, and is used to monitor the surface tem-
fixing heater, and the condition of the scanning lamp.
2. Mechanism
Figure 3-45a shows the error detection circuit,
and Table 3-5 lists the conditions for its activation.
The error AC shutoff relay (RLl) goes OFF in
response lo the output of the errordetection circuit in
terms of both software and hardware.
The signals (LIGHT, SSRON, HTRD, TH) shown
tion circuit.
tion circuit to issue the ACOFF signal, thereby acti-
vating the AC shutoff relay (RLl).
Fixing heater (Hl)
Figure 3-45a
a. Detection by Software
Ifanerrorinthesurfacetemperatureoftheupper
fixing roller (220°C) or the activation of the fixing
heater is detected in terms of software, the error AC
shutoff relay (RLl) is turned OFF immediately and
CANON NPZl20/2MO RN.0 OEC. 1992 PAINTED IN JAPAN (IMPRIME AU JAPONI
DC controller