Voltage, Ground, And Continuity Readings; Voltage Readings; Ground Checks; Continuity Readings - Lexmark 4227 - Forms Printer B/W Dot-matrix Service Manual

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Voltage, ground, and continuity readings

Voltage readings

All DC voltages must be within +5% through -10% of the values to
be considered correct. Unless stated otherwise, all connectors
should be connected normally when a voltage measurement is
done.
When a "line voltage" measurement is to be done, the voltage on
United States and Canada machines should be between 100 V ac
and 127 V ac. On World Trade machines, 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 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.
WARNING: Always unplug the power cord before doing any conti-
nuity 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.
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