Canon NP6012F Service Manual page 57

OPERATIONS AND TIMING-
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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.
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.
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1995 CANON INC.
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Pre-exposure lamp (LAZ)
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DC controller PCB
Figure 3-304
CANON NP6012/NP6Oi2FINP6212 REV.1
SEPT. 1995 PRINTED IN JAPAN (IMPRIMi AU JAPON) 3-19