Canon LBP-1000 Service Manual page 57

quency comparator, and keeps controlling the /ACC signal and /DEC signal so that the scan-
ner motor rotation number becomes the specified value. The CPU determines whether the scan-
ner motor is rotating at the specified rotation number or not by monitoring the /BDI signal.
When stopping the scanner, the SCANNER MOTOR DECELERATION signal (/DEC) is set to
"L" to reduce the scanner rotation number.
The CPU detects the following failures and error by monitoring the /BDI signal sent from the
BD PCB, and reports it to the video controller.
1) Scanner failure
The CPU assesses a scanner failure when the scanner motor rotation number does not reach
the specified value within 10 seconds after the start of scanner motor rotation.
2) BD failure
The CPU assesses a BD failure when the /BDI signal is not detected within 1 second after
completion of scanner motor forced acceleration or when the /BDI signal is not detected for
0.5 seconds after the scanner motor rotation has reached the specified number.
3) BD error
The CPU assesses a BD error when the input cycle of /BDI falls out of the range ±1.7% of
the scanner motor specified rotation number after the scanner motor rotation has reached
the specified number.
CHAPTER 2
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