Gestetner B070 Service Manual page 1041

Tech Service Bulletin No. B070/B071 – 018
Tandem Tray Paper Feed Sensor Jam
Symptom: Feed sensor jam from mis-feed of 3 or more sheets.
Before the trailing edge of the first sheet clears the feed/reverse rollers, the pickup roller, (already rotating)
from drive supplied through the feed roller, lowers and begins feeding the next sheet. Then the trailing edge
of the first sheet crosses with the leading edge of the next sheet around the area of the feed sensor.
B070/B071 Jam Code 53 Timing Chart (LT LEF - Tray 1)
Pick-up Solenoid
Paper Feed Clutch
Paper Feed Sensor
1st Sheet
If the multifeed occurs, the 1st
multifed sheet is already at the
paper feed sensor area. (Even with
the feed clutch off, the paper
reaches the feed sensor via the
inertia of the feed roller).
With multi-feeds of 3 sheets or more, the previous sheet stops at the registration section and then next sheet
(blue) is fed to the feed sensor via the inertia of the feed roller. The paper feed sensor then turns ON,
followed by the pick-up solenoid a certain number of ms later. If the paper slips at all on the way to the grip
roller, it can collide with the previous sheet around the feed sensor (which detects presence of paper and
triggers jam).
Note: This symptom occurs only for LT LEF fed from Tray 1.
Pickup SOL OFF.
CÓPIA NÃO CONTROLADA
Grip Roller
Feed Sensor
CÓPIA NÃO CONTROLADA
Pick-up SOL turns ON once
predetermined interval expires (since LE
detected by feed sensor).
2nd Sheet
Countermeasure:
Pick-up solenoid ON timing delayed
(10mm worth of time), to allow leway
for the previous sheet even if it should
slip.
Registration roller
NOTE:
Pickup solenoid ON/OFF timing
(ON: pickup roller contacts paper,
OFF: separates):
-The solenoid turns OFF when the
paper's leading edge reaches the
feed sensor.
-The solenoid turns ON Xms after
the paper has reached the feed
sensor (extended 10 mm worth).
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