Service manual

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EPSON LQ-300+ Revision C
Troubleshooting Troubleshooting 47
3.2.3 Identify Problems From Symptoms
This section contains procedures to identify problems from abnormal symptoms.
Repair/replacement is usually performed as a unit, however, parts level replacement
can be performed if neccasary.
Find your symptom referring to the table below and go to the corresponding table.
Table 3-2. Symptoms and Solutions
Symptom Problems Check Table
When power is applied,
the printer does not
operate.
Control panel LED does not operate at
all.
Table 3- 3 on page 47
Printer mechanism does not operate at
all.
Table 3- 4 on page 47
When power is applied,
the printer becomes fatal
error.
• Control panel indicates fatal error.
• The printer indicates error after
initialization.
Table 3- 5 on page 48
Self-test print is
abnormal.
• Platen gap is not correct.
• Printhead and ribbon mask is
abnormal or their life are over.
• Vertical direction printing quality is
abnormal.
Table 3- 6 on page 48
Paper feed is abnormal.
• Paper feed operation is not
performed.
• Paper switching is abnormal.
• Line feed is not equal.
• Skew is generated.
Table 3- 7 on page 48
Control panel and
switches do not operate
properly.
• LED indication is abnormal.
• Cannot input from switches.
Table 3- 8 on page 48
Printing operation is
abnormal when it is on-
line.
• Self-test is normal, but the printing
from host computer is abnormal.
Table 3- 9 on page 49
Table 3-3. Control Panel LED Does Not Light On.
Cause Check Point Y/N Solution
Blowout of a fuse on
the power board.
Is a fuse on the power
board blew out?
YES
Check the electric circuit and
printer mechanism. If there is no
short circuit, replace the fuse.
Connector is not
connected to the
power board.
Are connectors
connected to the
power board
properly?
NO Replace the power board.
Power switch is
defective.
Is conductivity of the
switch is OK?
YES Replace the power board.
Power board is
defective.
Are +5VDC and
+35VDC OK when
the power is on?
NO Replace the power board.
Power board and the
main board are not
connected properly.
Is CN8 connected
properly?
NO Connect CN8 properly.
Main board is
defective.
- - Replace the main board.
Control panel harness
is not connected
properly.
Is the harness of the
control panel
connected properly?
NO Connect the harness properly.
Control panel board
or harness is
defective.
- - Replace the control panel.
Table 3-4. Printer Mechanism Does Not Operate.
Cause Check Point Y/N Solution
Any of CN3 to CN12
is not connected to the
main board properly.
Are all connectors
connected properly?
NO Connect them properly.
Main board is
defective.
- - Replace the main board.
Printer mechanism is
defective.
- - Replace the printer mechanism.