Service manual

Troubleshooting
Revised 2/18/05 6-17
Symptoms and Solutions
This section describes some specific troubleshooting
techniques to try for several symptom categories.
Noise/Artifact Problems
Noisy waveforms are the most common type of problem
with neurodiagnostic systems, as the amplifiers are very
sensitive, and able to pick up minute amounts of noise
from a variety of sources. Evoked potential tests and
sensory nerve conduction tests are most affected by
noise problems.
The causes of noise problems may be:
• poor electrode application
• incorrect filter/sensitivity settings
• incorrect stimulus rate settings
• a noisy environment
• faulty amplifiers
Use the following checklists to determine and resolve
the most common noise-related problems.
Troubleshooting Noise: Environmental Checklist
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Items to check Detail
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1. Make sure any CRT monitor in the room is separated
from the amplifier.
We recommend 2 to 3 feet away from the
amplifier. LCD flat panel displays are not a
significant problem.
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2. Turn off all fluorescent lights or dimmer switches
when operating the equipment.
Do not have dimmers set to the middle
position.
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3. Turn off and unplug any equipment in the same room
as the system.
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4. Remove any outlet strips or extension cords, if used,
to connect the system to the wall outlet
System should plug directly into the wall
from its isolated power supply or from the
cart-mounted medical grade power strip
supplied by VIASYS.
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5. If using a metal bed, is it grounded? Verify with an electrician or Biomedical
Engineer.
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6. Use a dedicated circuit (line) for the system. Make
sure no other devices are plugged into the same
outlet
Verify with an electrician or Biomedical
Engineer.
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7. Make sure your wall outlet has proper grounding.
Approximate age of wiring in the walls: __________
Verify with an electrician or Biomedical
Engineer.
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8. Do you have a radio station transmission tower
nearby? Yes: ___ No: ___
If Yes, enter approximate distance in ft. to
the station.
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9. Are there any large electrical devices in adjacent
rooms? Above or below? Yes: ___ No: ___
X-ray equipment, MRI, refrigerator, air
conditioner, elevator motors, etc.
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10. Are there any large power feeds or circuit boxes in
nearby walls? Yes: ___ No: ___
Circuit breaker boxes, fuse boxes, large
metal containers, etc.
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11. Are there any data cables in the walls of the testing
room? Yes: ___ No: ___
GND shield terminated only at one end.