Scanning Lamp Error Activation Detection Circuit; Fixing Heater Error Activation Detection Circuit; Detection By An Ssr; Detection By A Thermistor - Canon NP6330 Service Manual

B. Scanning Lamp Error Activation Detection Circuit
The state (activation) of the scanning lamp (LA1) is monitored by the gate array
(IC115) on the DC controller PCB.
The lamp regulator sends the lamp ON detection signal (LDT) to the DC controller
while the scanning lamp remains on. If the gate array detects the LDT signal for 22 sec
continuously, it will identify the condition as an error in the lamp and, as a result, will
cause the error auto power-off signal (PWOFF*) to go '0'. In response, the relay inside
the power switch (SW1) turns on to turn off the power switch, thereby cutting off the AC
power to the DC power supply PCB.
C. Fixing Heater Error Activation Detection Circuit

1. Detection by an SSR

The SSR sends the SSR drive signal (MSSRD, SSSRD) to the DC controller while
the fixing heater (H1, H2) remains on.
If the gate array (IC115) on the DC controller PCB detects the MSSRD signal or the
SSSRD signal in the absence of the heater drive command (MHRD, SHRD), it will
identify the condition as an error in the heater and, as a result, will indicate 'E004' and
at the same time will cause the error auto power-off signal (PWOFF*) to go '0'. In
response, the relay inside the power switch (SW1) will turn on to turn off the power
switch, thereby cutting the AC power to the DC power supply PCB.

2. Detection by a Thermistor

The upper fixing roller is equipped with a thermistor (TH1) used to detect fixing
temperature.
If the temperature of the upper fixing roller fails to reach a specific level within a
specific period of time or it exceeds 220°C, an error code will be indicated; at the same
time, the gate array on the DC controller PCB will turn off the power switch to cut off the
AC power to the DC power supply PCB. (See Chapter 11.)
COPYRIGHT © 1997 CANON INC.
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CANON NP6330 REV.0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 7 CONTROLS AND EXTERNALS
7-7