Controlling The Scanning Lamp; Outline - Canon FC220 Service Manual

II. Controlling the Scanning Lamp
A. Outline
Figure 3-201A shows the circuit that controls the scanning lamp (fuse lamp), and the
circuit has the following functions:
• Turns the scanning lamp ON and OFF.
• Controls the intensity of the scanning lamp.
An intensity sensor (PD601) is provided to ensure that the original will be illuminated
after the intensity of the scanning lamp has stabilized.
The intensity of the scanning lamp is checked by the lamp intensity detection signal
(LID) to make sure that the intensity has reached the specified value.
In addition, a rush current protection circuit is provided to prevent rush current
occurring when the lamp turns on.
J621
-4
-
+
-3
(-1)
VR604
-
+
5V
Amplifier circuit
Control panel PCB
The number within parentheses represents the PC400/FC200.
COPYRIGHT © 1998 CANON INC.
Scanning lamp
(LA1-LA8)
J108-1
Intensity sensor
(PD601)
J108-2
J601 J202
-10 -13
(-5)
FIgure 3-201A
CANON PC400/420/430,FC200/220 REV.0 JAN.1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
+24VU
Q143
Rush current
protection circuit
Lamp intensity sensor signal (LID)
DC controller/DC power supply PCB
CHAPTER 3 EXPOSURE SYSTEM
Lamp
driver
circuit
Lamp ON
signal
(LAPWM)
3-7