Canon PC300 Service Manual page 57

Ss OPERATIONS AND TIMING
2. Operations
a. Turning the Scanning Lamp ON and
OFF
+ Square waves of the FLPWM com-
mand corresponding to the output of
the amplifier circuit are generated to
the lamp driver circuit. (Q143 ON)
Le Current flows into the filament of
the lamp, causing the fluorescent
lamp to go ON at high frequency.
b. Controlling the Intensity of the Scanning
Lamp
* If the intensity of the lamp is low when
the lamp goes ON,
Initial power of the intensity sen-
sor PD601 is low.
Output voltage of the amplifi-
er circuit is high.
Duty ratio (H) of the out-
put of the microproces-
sor (LAPWM command)
- high.
Current flowing to
the lamp increases.
* If the intensity of the lamp is high when
the lamp goes ON,
Initial power of the intensity sen-
sor PD601 is high.
he Output voltage of the amplifi-
er circuit is low.
Duty ratio (H) of the out-
put of the microproces-
sor (LAPWM command)
grows low.
eet flowing to
the lamp decreas-
es.
« If the microprocessor finds out that the
scanning lamp has remained on for 2
min at such times as not prescribed, it
activates the self diagnostic mecha-
nism; the results are indicated by 'E6'
for the PC320/325/FC230 and 'JAM'
for the PC300/FC210.
. Controlling the Intensity of the
Scanning Lamp (VR604)
You must adjust the intensity of the lamp
if you have replaced the scanning lamp
unit, intensity sensor or control panel
PCB; see p. 3-46.
Note:
You must adjust the AE mechanism after
adjusting the intensity. (PC320/325/
FC230)