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Service Guide ML320/ML321
Chapter 4 Failure & Repair Analysis
4.4.02 Common Problems
Nothing happens when the printer is powered ON.
Make sure the printer is plugged in.
Check the power cord connection to the printer and the outlet.
If a power strip is being used, make sure the strip is powered ON.
The ALARM lamp is lit.
The printer may be out of paper or the paper may have jammed. The SEL lamp will
not light. After loading paper, press the SEL switch.
If the ALARM lamp does not go out after paper is loaded,
refer to Section 4.4 (
) of this
Service Handbook.
The printer does not print when the computer sends it data.
The printer may be deselected. Make sure that the SEL lamp is lit. If it is not, press the
SEL switch.
The paper keeps jamming.
Verify that the top of form is set so that the paper is held in place by the bail bar. If the top
edge of the page is below the bail, it will catch on the bail as it advances. Do not use the
FORM FEED switch to load paper into the printer.
If the paper does jam, power OFF the printer. Carefully back the paper out of the paper path
by using the platen knob. Remove any shreds of paper from the paper path.
The printer suddenly changes to unidirectional printing. It then stops printing completely.
The MENU light is flashing.
This indicates a Printhead Overheat Condition. When the printer prints for a long period of time,
heat will build up in the printhead. When the printhead temperature reaches 100 degrees Celsius,
the printer will print unidirectionally. If the temperature reaches 110 degrees Celsius, printing
will stop until the printhead cools. Printing will resume after the printhead cools.
Output is missing dots.
Check the headgap setting. Move the head gap lever to a lower setting.
- Setting 1 is for one or two part forms.
- Setting 2 is for three or four part forms.
- Setting 3 is for envelopes and extra-thick paper.
Perform the Printhead Gap Adjustment.
Refer to Section 3.3 (
) of this Service Handbook for
details.
Refer to RAP 03 (
).
Files do not print the way the printer menu and front panel are set.
Before sending a file to a printer, many word processors send an initialization string. This string
