Ricoh FT7770 Service Manual page 572

30 April, '89
Service Call 10 - Home Sensor
When the Start key is pressed and the scanner motor has
been activated, the scanner home sensor stays off for more
than 2 seconds.
When the Start key is pressed and the scanner motor has been
activated, the CPU does not receive the scanner home position
sensor ON signal.
o The scanner home position sensor does not turn off within 250
milliseconds after the scanner motor turns on.
o The scanner home position sensor turns on before the encode
count indicates the scanner "Speed Down Point".
Check if the scanner friction is within specifications
(600
± 150 g).
Y N
I
Clean and lubricate the scanner guide rod.
Check that the scanner drive wire is mounted correctly
moves smoothly.
o Turn the main switch off.
o Remove the exposure glass.
o Open the front doors.
Is the output of CN202-A8 HIGH (15 volts) when the scanner is in
the home position?
Is the output of CN202–A8 LOW when the scanner is out of the
home position?
Y N
o Replace the home sensor.
o Check and correct the harness and connector.
Replace the main board.
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a n d