Kyocera DF-420, Service Manual

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3MH
1-4-9
1-4-4 Electric problems
Troubleshooting to each failure must be in the order of the numbered symptoms.
Problem Causes Check procedures/corrective measures
(1)
The paper feeder
does not operate
when the main power
switch is turned on. 1. Poor contact in the con-
nector terminals.
Reinsert the connector. Also check for continuity within the con-
nector cable. If none, remedy or replace the cable.
2. Defective cassette left
cover switch.
Check for continuity across the contacts. If none, replace the cas-
sette left cover switch.
(2)
The cassette drive
motor does not oper-
ate. 1. Poor contact in the con-
nector terminals.
Reinsert the connector. Also check for continuity within the con-
nector cable. If none, remedy or replace the cable.
2. Defective drive transmis-
sion system.
Check if the rollers and gears rotate smoothly. If not, grease the
bushings and gears. Check for broken gears and replace if any.
3. Defective cassette drive
motor.
Run maintenance item U030 and check if the cassette drive motor
operates. If not, replace the cassette drive motor.
4. Defective cassette main
PWB.
Run maintenance item U030 and check if the cassette drive motor
operates. If not, replace the cassette main PWB.
(3)
The cassette paper
feed clutch does not
operate. 1. Broken clutch coil. Check for continuity across the coil. If none, replace the clutch.
2. Poor contact in the con-
nector terminals.
Reinsert the connector. Also check for continuity within the con-
nector cable. If none, remedy or replace the cable.
3. Defective cassette main
PWB.
Run maintenance item U032 and check if following terminals on
the cassette main PWB goes low. If not, replace the cassette main
PWB.
Cassette paper feed clutch: YC8-2 on the cassette main PWB
(4)
The message
requesting paper to
be loaded is shown
when paper is
present on the cas-
sette. 1. Poor contact in the con-
nector terminals of cas-
sette paper switch.
Reinsert the connector. Also check for continuity within the con-
nector cable. If none, remedy or replace the cable.
2. Defective cassette paper
switch.
If the level of following terminal on PWB does not go low when the
switch is turned on and off, replace the switch.
Cassette paper switch: YC5-2 on the cassette main PWB
(5)
The size of paper on
the cassette is not
displayed correctly. 1. Poor contact in the con-
nector terminals of cas-
sette paper size width
switch or cassette paper
size length switch.
Reinsert the connector. Also check for continuity within the con-
nector cable. If none, remedy or replace the cable.
2. Defective cassette paper
size width switch or cas-
sette paper size length
switch.
If the level of following terminal on PWB does not go low when the
switch is turned on and off, replace the switch.
Cassette paper size width switch: YC4-4 on the cassette main
PWB
Cassette paper size length switch: YC4-5, 6, 8 on the cassette
main PWB
(6)
A paper jam in the
paper feeder is indi-
cated when the main
power switch is
turned on. 1. A piece of paper torn
from copy paper is
caught around cassette
feed switch 1 or 2.
Check visually and remove it, if any.
2. Defective switch. Run maintenance item U031 and turn switch on and off manually.
Replace the switch if indication of the corresponding switch is not
light.
Cassette feed switch1, 2