ADInstruments Bio Amp Owner's Manual page 37

Appendix B Troubleshooting
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The BNC or I C cable is faulty.
• Replace the cable and try again. Immediately label all cables proved faulty
so that you don't use them again by accident.
The Bio Amp is faulty.
• This is the least likely event. If the front-end will not work properly after
the previous measures, then try using it on another PowerLab. If the same
problems recur with a second PowerLab, the front-end may be faulty.
Contact your ADInstruments representative to arrange for repairs.
The trace will not zero properly when adjusting high-pass filtering
The Bio Amp is receiving signals at a level that has saturated the input
amplifier, resulting in a large offset. This is normally due to poor contact
between the electrodes and the subject.
• Check the connections for proper contact and try again.
If you are using the Dual Bio Amp or the Octal Bio Amp, with the
0.02 Hz high-pass filter, the trace can take a long time to zero by itself.
• Click the DC Restore button in the Bio Amp dialog to bring the trace back
to zero quickly.
The signal appears to display a constant amplitude oscillation
Frequency interference from power lines can become superimposed on the
biological signal being measured.
• You can use the internal notch filter in the Bio Amp to remove excessive
line voltage frequency interference (use the checkbox in the Bio Amp
dialog).
If you are using cables and leads that were not supplied with your Bio Amp,
they may be unshielded or of low quality.
• Check to make sure that you are using high-quality shielded cables and
high-quality leads. Only the supplied Bio Amp cable and leads should
really be used.
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