Canon NP-70 Service Manual page 69

3-28
NP -70
Block Actions Occurring
The following points are the actions that contribute to the activation of solenoid
SL7 when either an "Exit" or "Delay" jam occurs. In order to make this chart
applicable to all modes of copying, only the steps related to the operation of the
circuit (within the cycle having the jam) are shown.
JAM
The condition of the jam circuit components, at the time of COPY button turn-on,
is shown here. These components will remain essentially stable until after the
copyboard begins advancing. Then, they will be progressively set to different states
for jam detection.
COPY-
"ON"
The actuation of MS 14, as the copyboard moves forward, not only signals the pick-
up of copy paper; it also prepares the Jam Detection Circuit for turn-on. This turn-
on will occur at the time of the next MS3A pulse, when relay K 1 1 is energized.
NOTE: In the case of "half-size" operation, this will have an effect only in the
first copying cycle. For repeat cycles, however, K11 will remain energiz-
ed and, thus, the Jam Detection Circuit will remain turned on until after
the last copying cycle is completed.
STEP 1 J
The release of MS 14 as the copyboard continues its advance results in the start of
capacitor C25 discharging.
STEP
2J
The first actuation of MS3A after MS14 causes the Jam Detection Circuit to turn-
on (due to the energizing of relay K11) for the purpose of detecting a "Delay"
jam occurring in the present copying cycle.
NOTE: In the case of "half-size" operation, K11 turn-on will occur only once
during the first copying cycle. For each subsequent cycle, the action of
MS3A will have no effect on K 11.
STEP 3J
The completion of the discharging of capacitor C25, begun in STEP 2J ,occurs
STEP 4J
in'this step. If no additional copies are made, the portion of the jam circuit capa-
ble of detecting "Delay" jams will be deactivated by the next MS3A pulse.
The copy paper picked up in STEP 2J now begins to exit the copier. Asa re-
STEP SJE
suit of the exiting action, a "Delay" jam detection is prevented. However, the jam
Detection Circuit is now set up for the detection of an "Exit" jam, as capacitor
C20 begins charging.
The copy paper picked up in STEP 2J fails to start exiting the copier as it
STEP
SJD
normally should. Thus, the gate of Q29 remains ON in preparation for the actua-
tion of microswitch MS2A.
Second Printing,lune, 1974
© CANON INC.