Canon NP6012 Service Manual page 64

—_ _ @@™™ ~~~=~—_S—— SSS OP ATIONS AND TIMING LY
C. Controlling the Pre-
Exposure Lamp
1. Outline
The intensity of the pre-exposure lamp
must remain constant at all times during
APVC measurement and to ensure stable
image reproduction (primary charging). To
ensure stable intensity, the copier corrects
variations among individual pre-exposure
lamps and fluctuations in the drive voltage.
106 -——_____—
+24V
2. Operation
The PWM reference value used to deter-
mine the intensity of the pre-exposure lamp
is stored in the CPU on the DC controller
PCB.
The CPU on the DC controller PCB
detects the voltage used to drive the pre-
exposure lamp and corrects the PWM refer-
ence value so that the pre-exposure lamp
may be driven at a specific intensity.
Reference:
You must enter the PWM reference value
(PREX_LP) in service mode whenever
you have replaced the pre-exposure
lamp.
PWM signal
r cPu
— (Q101)
DC controller PCB
Pre-exposure lamp (LA2)
Figure 3-304
COPYRIGHT © 1995 CANON INC. CANON NP6012/NPGOI2F /NP6212 REV.1 SEPT. 1995 PRINTEDIN JAPAN (IMPRIME AU JAPON)
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