Ricoh FT4460, Service Manual, Page: 375 / 413

28 February 1989
2.9 CODE #28 AND #29
- Phenomena -
SC #28: Lens home position sensor output stays HIGH
SC #29: Lens home position sensor output stays LOW
- Possible Causes -
1. Lens home position sensor malfunction
2. Lens drive motor malfunction
3. I/O control board malfunction
4. Lens housing overload (binding)
- Actions -
1.
2.
3.
Check the lens home position sensor by measuring the voltage at
CN301-B18 on the I/O control board while manually interrupting and
uninterrupting the sensor (interrupted: 5V, not interrupted: 0V).
If the output does not change, replace the lens home position sensor.
If the output does change, replace the lens drive motor or the I/O control
board.
If the lens drive motor does not turn and nothing is blocking movement of
the lens housing, perform the following:
Check the lens drive motor by measuring the drive pulses at CN301-A5,
B5, A4, and B4, and re-intialize the copier.
If the output remains constant at +24V, replace the I/O control board.
If the output changes at each terminal, replace the lens drive motor.
If the output remains constant at 0V, check CN301 A6 and B6. If either is
0V, replace the l/O control board.
If A6 and B6 are +24V, replace the lens drive motor.
Check the load on the lens housing.
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