Canon ImageCLASS MF4690 Service Manual - page 79
Chapter 7
7-3
7.3 Detection Jams
7.3.1 Jam Detection Outline
7.3.1.1 Overview
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The machine has the following paper sensors to detect the presence/absence of paper at the time of startup, opening the door, or feeding a paper, as well as to detect
whether a paper is fed normally.
1. Leading edge sensor (PS801)
2. Paper width sensor (PS802)
3. Delivery sensor (PS803)
4. Delivery paper width sensor (PS804)
In terms of jam, it is judged by whether a paper is at the sensor assembly at the time of the check time memorized in the CPU beforehand. If the CPU judges as the
occurrence of jam, the printing operation is aborted and at the same time, it notifies it to the SCNT board.
7.3.2 Delay Jams
7.3.2.1 Pickup Delay Jam
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In order to prevent the pickup delay jam due to the pickup failure, the machine executes the retry control that performs the pickup operation up to twice.
In the second pickup operation, if the leading edge sensor (PS801) cannot detect the leading edge of paper within about 1.45 sec since the pickup solenoid (SL1)
turns ON, the DCNT board judges as the pickup delay jam.
7.3.2.2 Delivery Delay Jam
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If the delivery sensor (PS803) cannot detect the leading edge of paper after passing about 1.65 sec from the detection of the leading edge of paper with the leading
edge sensor (PS801), the DCNT board judges as the delivery delay jam.
7.3.3 Stationary Jams
7.3.3.1 Pickup Stationary Jam
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If the trailing edge of paper cannot be detected after passing about 5.4 sec since the leading edge sensor (PS801) detects the leading edge of paper, the DCNT board
judges as the pickup stationary jam.
7.3.3.2 Delivery Stationary Jam
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If the delivery sensor (PS803) cannot detect the leading edge of paper within about 1.48 sec after the leading edge sensor (PS801) detects the trailing edge of paper,
the DCNT board judges as the delivery stationary jam.
7.3.4 Other Jams
7.3.4.1 Door Open Jam
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If the leading edge sensor (PS801) or the delivery sensor (PS803) detects a paper when door open is detected, the DCNT board judges as the door open jam.
7.3.4.2 Wrapping Jam
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CPU executes the wrapping jam detection after it judges there is no delivery delay jam present.
If the delivery sensor (PS803) detects the trailing edge of paper within the predetermined time (from after about 0.08 sec since the detection of the paper leading
edge by the delivery sensor (PS803) until about 1.09 sec after the detection of the paper trailing edge y the leading edge sensor (PS801)), CPU judges as the wrapping
jam.
If it judges as the wrapping jam, it notifies the occurrence of the delivery stationary jam to the SCNT board.