Jam Check Timing - Ricoh FT7770 Service Manual

30
April, '89

Jam Check Timing

3.
The above timing chart shows the jam check timing for A4 (8½" x 11") paper.
The paper feed MC stops momentarily for pre-registration when the paper
actuates the paper feed sensor. (This is true for all three feed trays.) The
paper feed sensor also checks for misfeeds. If the paper does not arrive at
the sensor within 300ms after the feed clutch turns on, a misfeed condition
exists.
All sensors after the paper feed section check for paper jams three times to
ensure that the paper moves at the correct timing. (OFF CHECK ---> ON
CHECK ---> OFF CHECK) In the registration section, the "OFF", "ON",
"OFF" checks are made at 10 milliseconds, 280 milliseconds, and 1370 mil-
liseconds after the registration MC turns on the second time. For all sen-
sors after the registration sensor, the timer for the "OFF" and "ON" checks
starts counting from the "ON" check timing of the previous sensor. For ex-
ample, the pick-off sensor's "OFF", "ON"
liseconds, 280 milliseconds, and 1370 milliseconds respectively after the regis-
tration "ON" check.
In the face down and duplex modes, the paper is fed to the inverter. The
exit sensor jam check timing in the face down mode and the duplex sensor
jam check timing in the duplex mode are different from other modes. In
these cases, the jam check timer starts when the trailing edge of the paper
passes the fusing sensor.
l
, and "OFF" checks come at 10 mil-
2-78
and