BioSemi.nl

My group have been working with the activeTwo equipment for a while now and had no problems.

However, in the past week we have had two occasions where the power light and the CM in range light have both switched off when plugging in the EEG pin electrodes (including CMS/DRL) but not when plugging in any other electrodes.

Is this a hazardous current limitation problem or something else? The electrodes all seem to be intact and the contacts haven't been contaminated with gel.

Naturally this problem only happens when I'm not the person in the lab, so I can't be any more specific. o_O

Besides the current limiter in the DRL circuit (which switches off the power supply to the active electrodes is larger then normal leakage currents are detected), the ActiveTwo has a secondary safety circuit which switches off the entire AD-box if faulty voltage levels are detected on the internal supply lines. A few incidents have indeed been reported where this internal safety circuit was triggered during plugging in of electrode connectors. When the connectors are plugged in at an angle, a short spike can be induced on the internal power lines (because some pins make contact, and other don't), which triggers the safety circuit. Simply switch the battery off and on again, to reset the AD-box (no safety issues involved, damage to the AD-box is not possible). The shut-down circuit should not act during normal operation. In cases where the AD-box shuts down unexpectedly (not caused by electrode connectors being plugged in/out), the box should be sent to BioSemi for checking and/or repair.

Best regards, Coen (BioSemi)