Cable Shorts Test - Printronix P7000 Series Maintenance Manual

Cable Shorts Test

This test determines if a cable has a short to ground or a pin-to-pin short (also
called a wire-to-wire short). Such shorts can be caused by cables resting on
or moving across sharp edges. The edges over time can wear away the non-
conductive shielding of the cable, exposing the conductor. A short occurs
when the exposed conductor touches another metal surface or conductor.
This procedure tests only the cables listed below that can be disconnected at
both ends:
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The Procedure:
1. Prepare the printer for maintenance (page 230).
2. Disconnect the cable to be tested at both ends, but leave the cable
3. Set your Ohmmeter to the 10K Ohm scale or the scale closest to 10K
4. Hold the two meter leads apart from each other (not touching anything)
Check for shorts to ground:
5. Attach the common meter lead (usually black) to a bare metal ground
6. Touch the positive meter lead (usually red) to another bare metal ground
IMPORTANT
When making continuity checks, touch the meter leads to the test points
for at least 2 to 3 seconds so your meter has time to display correctly.
7. At one end of the cable, touch one of the pins with the positive (usually
Intermediate cables of devices in the Main Wire Harness Test Tables:
Card Cage Fan
Left Ribbon Motor
Right Ribbon Motor
Exhaust Fan (in cabinet models)
Magnetic Pick-up Unit (MPU)
Shuttle Motor Intermediate Cable
Hammer Bank Power and Logic Intermediate Cables
Control Panel Assembly Intermediate Cable
Power Stacker Logic and Power (Intermediate) Cables
routing as it was before you started this procedure.
Ohms.
and note how your meter indicates an open circuit. For example, some
meters read OL (Over Load), -1, flashing display, infinite resistance, etc.
Record this indication for later reference.
point on the printer (e.g., a bolt head on the shuttle casting).
point and verify continuity. (Continuity is a low resistance reading of less
than 1 Ohm.)
red) meter lead while the common lead (usually black) is still touching a
ground point.
Adjustments and Tests
261