Lexmark 2390 003 - B/W Dot-matrix Printer Service Manual page 45

FRU/Symptom
2 Machine power
sometimes turns
off.
3 Intermittently poor
print quality.
Action
The cause of this problem may be that the
power circuit is failing, or the wiring is
intermittently open. Check the following in
sequence:
1. Check the customer's outlet voltage and
be sure it is within tolerance.
2. Check the continuity of the power cord.
3. Disconnect the power supply cable from the
connectors CN11 on the main logic board
and CN1 on the sub logic board. Turn the
printer power on and check all dc output
voltages at CP11 and CP1.
Be sure the output voltages are as follows:
CP11-1 (+26 V dc ±10%) & CP11-2 (GND)
CP11-3 (+5 V dc ±5%) & CP11-4 (Signal GND)
CP 1-1 (+26 V dc ±10% & CP1-2 (GND)
CP 1-3 (+5 V dc ±5%) & CP1-4 (Signal GND)
If one of the voltages is 0, go to the
Service Check" on page
are not 0 but are incorrect, replace the power
supply unit.
Do the following:
• Remove paper jams from the paper path.
• Clean all feed roller surfaces.
• Clean the ribbon shield and printhead.
• Clean the platen surface.
• Install the ribbon cartridge correctly.
• If the ribbon end of life has been reached,
have the customer replace the ribbon
cartridge.
Diagnostic Information 2-21
"Power
2-32. If the voltages