Automatic Power Control (Apc) - Gestetner G056 Service Manual

PRINTING PROCESS

Automatic Power Control (APC)

Engine Board
GAVD
• To prevent the intensity of the laser beam from changing because of
temperature, the machine monitors the laser beam with a photodiode (PD). The
PD passes the current to the LD control IC. The machine adjusts the current to
the laser diode by comparing it with the reference level from the regulator. The
LD control IC on the engine board controls this.
• The laser diode power is adjusted on the production line. Do not touch the
variable resistors on the LD unit in the field.
G056/G058
+ 5 V L D
A L O F F A P D
A L D
Data
LD
Control IC
B L O F F
B P D
D R O P E N
B L D
VREF
LD Drive Board
P D
Regu-
lator
6-8
L D
P D L D
G056D503.WMF
SM