Epson GT-1200, Service Manual

Page: 112 / 157

ADF Troubleshooting
Rev. A 3-6
3.1.2.2 Paper Eject/Reverse Motor Check Point
A 4-phase stepping motor is also used for the paper eject/reverse motor,
and coil resistance between each coil is
2.6
W ±
10% . Internal coil
connection is shown below.
Y e l l o w
B l u e
R o t o r
1
3
5
7
9
1 1
B l a c k
R e d G r e e n
W h i t e
* A
A
A c o m
B
B c o m
* B
Figure 3-4. Internal Connection of the Reverse Motor
3.1.2.3 Solenoid Check Point
This ADF is equipped with 2 solenoids; shutter weight solenoid and
reverse solenoid. They are easily activated by turning on the coils.
Therefore, you can check the condition of the solenoid by measuring the
resistance between 2 pin cables. Refer to Table 3-3 for the correct
resistance of the solenoids.
Table 3-3. Solenoid Resistance
Solenoid Coil Resistance
Shutter weight solenoid
28
W ±
10%
Reverse solenoid 80
W ±
10%
3.1.2.4 Paper Size Sensor
Size of the document set in the ADF paper tray is detected by aligning the
edge guide with the document. The document width measured by the
edge guides is converted into the corresponding sliding resistance, which
is fed back to the scanner. Since failure in outputting appropriate VR
causes the scanner to operate inappropriately for the document size, the
sensor must be checked for the correct resistance when necessary.
Refer to Table 3-4 for different document sizes and corresponding VR
output values.
Table 3-4.
Document Size and Corresponding VR Output
Document Size VR Output
B5 (Portrait) 3.53 to 3.18 V
A4 (Portrait) 2.78 to 2.47 V
B5 (Landscape) 1.53 to 1.27 V
A4 (Landscape)
A3 (Portrait) 0.45 to 0.27 v