Service manual

EPSON LX-300+ Revision A
Troubleshooting Troubleshooting 61
3.2.4 Unit and Parts Check
This section describes the checking method of the printhead, motors and
sensors to find the defective units and parts.
3.2.4.1 Printhead Check
By measuring the direct current resistance of the printhead coil, you can
check if it is all right.
Figure3-2. Head Coil Pin No.
Table 3-9. Printing Operation is Abnormal When it is On-Line.
(Self-Test is Normal.)
Cause Check Point Y/N Solution
Initial setting is
wrong.
Check the initial
setting with the
default setting. Is it
OK?
NO
Reset the setting or use the
EEPROM clear to reset setting
to the default.
Interface cable
is not
connected
properly.
Are cables
connected
properly?
NO Connect them properly.
Interface cable
is defective.
- - Replace the interface cable.
Main board is
defective.
- - Replace the main board.
Firmware is
defective.
Is the firmware
version latest?
NO Replace the firmware.
W ARNING
When repairing the unit, make sure to turn the printer off and
plug off the power cable except when this manual specifies to
keep the power on.
Table 3-10. Printhead Coil Resistance
Item Operation Specification
Printhead
1. Set the multimeter to the resistance
measuring range.
2. Connect the one side of the probe to C.
3. Connect the other side of the probe to
corresponding head pin No.
33.3 ± 3.3
Ω
(at 25°C/phase)
Looked From Point A