Lamp Regulator - Ricoh FT7770 Service Manual

30
April, '89
Power to the exposure lamp control circuit (+24 volts) is input at CN228-10.
Additionally 100 volts ac is input into the lamp regulator when RA102 is
energized (main switch on, covers closed).
To energize the exposure lamps, the main board supplies a LOW trigger at
CN208-A3. The trigger is supplied 1.2 seconds after the main motor turns
on. The trigger turns on the LED, which activates the phototransistor. The
control circuit then turns on the exposure lamps.
When the lamps are on, the monitor signal goes HIGH.
main board that the lamps are on.
only during forward scan, which lasts approximately one second.
The exposure lamp switch controls the lamp regulator output voltage. The
switch increases voltage (upper position) and decreases voltage (lower posi-
tion). The switch is usually used to increase the exposure lamp voltage so
blue background/lines and paste-up lines are not copied.
The monitor signal line should be HIGH
2-14
This informs the