68 Theory of operation C9148-90909
ADF cover sensor (PS10)
The ADF door-open sensor (PS10) detects ADF door status (open or closed). If the ADF door is
opened, a FLATBED COVER OPEN message appears on the control-panel display. If the ADF door
is opened during the document transport process, the ADF drive-motor stops and a door-open
message appears on the control panel.
Document-detect sensor (PS2)
The document-detect sensor (PS2) detects the presence of documents when they are placed
into the ADF document input tray.
Leading-edge sensor (PS1)
When a document enters the document transport path, it must pass the leading-edge sensor
(PS1) within a specified amount of time. If it does not, a paper-jam message appears on the
control-panel display.
ADF motor
The ADF motor is controlled by the scanner controller board. When the scanner controller
receives the scan command, the ADF motor rotates counterclockwise, which starts rotation of
the feed and delivery rollers.
Document pickup process
When the document pickup solenoid is activated, the pickup and separations rollers begin to
rotate. If more than one source document is in the pickup tray, the separation roller and
separation pad clear the multiple feed, and then the first document is sent toward the flatbed.
Document jams
The scanner controller board detects a jam by verifying that each document passes the leading-
edge sensor in a specified amount of time. If a document does not pass by the sensor in time,
the scanning operation stops. A document-jam message appears on the control-panel display,
and the user must clear the jam. The scanner controller board can detect two types of jams:
● Document-delay jam: If the leading-edge sensor does not detect the leading edge of the
document after the document pickup solenoid is activated, the scanner controller initiates a
document-delay jam signal.
● Document-stationary jam: If the leading-edge sensor does not detect the trailing edge of
the document after it detects that the leading edge has passed, the scanner controller board
initiates a document-stationary jam signal.
Scan-unit intake fan
The intake fan draws fresh air into the flatbed assembly. It is controlled by the fan-drive circuit,
which is located on the scanner controller board. The fan is off in PowerSave mode, it rotates at
half-speed when the product is idle, and at full-speed during the scanning process. The intake
fan motor is fault-protected. If the fan motor fails, the message 30.01.06 Scan Failure appears
on the control-panel display.
CAUTION The fan must be replaced so that it draws air into the flatbed. Failure to correctly position the fan
can result in damage to MFP components. Verify that the airflow arrow (located under the drive-
belt tension bracket) embossed on the fan housing points into the flatbed. See, “Correctly orient
the intake fan and bracket” on page 107.
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