Geodesic Sensor Net Technical Manual page 111

• If an individual sensor is providing poor EEG, try using a pipette (see page 117)
to add more electrolyte.
• Try gently removing the sponge from its pedestal to inspect it more carefully,
checking for dry spots caused by overcompression. Trim away a little sponge if
needed, rewet with electrolyte, reinsert into pedestal, and retest.
• Note the result of placing a piece of sponge (moistened with electrolyte)
between the sensor's sponge and the scalp.
• Check that sensors are properly seated. Use the foot of the pedestal to part the
hair as you seat the sensor. Use a pipette to part the hair in difficult areas during
seating. Right after applying the Net, try seating the sensors at the back of the
head first or where the subject's hair is thick. Thick hair tends to absorb
electrolyte.
• If some sensors are not making sound contact, the Net may be the wrong size or
may have been overstretched. Try a different (smaller) Net.
• If some sensors ride up or flip, try a larger Net; adjust the eye channels using
the cord locks.
Loose, Improper, or Faulty GSN Connectivity
• Check that connections are sound. Unplug and replug the connectors, checking
for bent or missing pins, corrosion, or buildup.
• On infant Nets, check to make sure that the shorting jack is plugged into the
connector if outrider sensors are not being used (see "Infant Nets" on page 44).
• Consider the possibility of a lead wire being internally faulty, resulting in an
open circuit existing somewhere between an electrode's connection to the lead
wire (inside the sensor) and the GSN Hypertronics plug. This can happen when
a lead is hyperextended, causing the wire inside the lead to lose its connection
to either the Hypertronics pin or to its associated electrode. For instructions on
how to diagnose a faulty sensor and/or lead, see the next section, "Faulty
Sensors."
Geodesic Sensor Net Technical Manual
S-MAN-200-GSNR-001 • January 31, 2007
11: Troubleshooting
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