Canon DU-82, Service Manual

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B. Paper Jam Detection
To detect presence of the paper and whether the paper has been correctly fed, the following
paper sensors are provided:
• Duplexing unit paper sensor (PS24)
• Reversing sensor (PS26)
The microcomputer (CPU) on the duplexing driver PCB determines whether or not a paper
jam has occurred by monitoring the paper at each of the sensors according to the pre-set 'check
timing' in the memory.
When the CPU assesses that a jam has occurred, the duplex feed operation is stopped, and
notification of the jam is sent to the DC controller.
1. Reversing unit delay jam
The duplexing driver detects a reversing unit delay jam if the print paper does not reach the
reversing sensor (PS26) within about 1.5 seconds after the duplex deflector solenoid turns ON.
2. Reversing unit stationary jam
The duplexing driver detects a reversing unit stationary jam if the trailing edge of the paper does
not pass through the reversing sensor (PS26) within the prescribed period of time (T1) after the
duplex deflector solenoid turns ON.
T1=about 2.8 seconds (A4), about 5.1 seconds (Ladger)
3. Duplex feeding unit delay jam
The duplexing driver detects a duplex feeding unit delay jam if the leading edge of the paper does
not reach the duplexing unit paper sensor (PS24) within the prescribed period of time (T2) after
the leading edge of the paper is detected by the reversing sensor (PS26).
T2=about 1.5 seconds (A4), about 2.2 seconds (Ladger)
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CHAPTER 2