Lexmark 2480 - Forms Printer B/W Dot-matrix, Service Manual

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Diagnostic Information
2-1
24xx
2. Diagnostic Information
Start
Make a quick visual check for defects (loose or broken parts,
unplugged connectors, paper jams, and so on).
Voltage, Ground, And Continuity Readings
Voltage Readings
All DC voltages must be 5% through -10% of the values to
be considered correct. Unless stated otherwise, all connectors
should be connected normally when a voltage measurement is
performed.
When a “Line Voltage” measurement is to be performed, the voltage
on United States and Canada printers should be between 100 V ac
and 127 V ac. On World Trade printers, the voltage is according to
each country’s specification.
Ground Checks
To check for a correct ground, measure the voltage between the
ground and a known good voltage source. The voltage
measurement must be the same as the source voltage to consider
that the ground is correct. Continuity measurements may be used to
check grounds, however, be sure to measure to a known good
ground using the lowest ohms scale and check for zero ohms.
CAUTION: Always unplug the power cord before doing any
continuity measurement.
Continuity Readings
When measuring continuity, be sure no back circuits affect the
measurement. If necessary, unplug connectors to remove any back
circuits. Zero the ohm range on the lowest scale (X1). An open
circuit will read infinity. A circuit with correct continuity will read zero
ohms.