sudden recording issue / CM out of range possibly due to GSR

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Erik
Posts: 4
Joined: Sat Oct 17, 2009 3:15 pm
Location: Marburg

sudden recording issue / CM out of range possibly due to GSR

Post by Erik »

Dear BioSemi Team,

we have recently had a series of issues with our 64 channels BioSemi Active Two system causing us to lose some valuable data. The problem seems difficult to replicate which is why we have not contacted you earlier. It occurs always in a while (every other participant or so) that in the middle of the session the "CM in range" light begins to flash and no data is coming in any longer. The issue seems related to the SCR/plethy sensors for (a) when we unplug this connector the flashing stops and (b) we did not experience this issue in an earlier experiment where we did not record SCR/plethy. However, we have run several subjects with good SCR/plethy recordings where there was no "CM in range" issue at all. The EEG electrodes also seem to work fine. The "CM in range" is on when only the EEG electrodes are placed in salt water. Removing or placing individual electrodes in the water does not affect the flashing "CM in range" button. We would be very thankful for your recommendations.

Kind regards

Erik

Coen
Site Admin
Posts: 1125
Joined: Fri Mar 26, 2004 7:00 pm
Location: Amsterdam, Netherlands
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Post by Coen »

The symptoms indicate a defect isolation of the plethysmograph sensor (small leakage currents trigger the safety circuits, blue light start blinking). Please sent the sensor to BioSemi for repair or replacement.

Best regards, Coen (BioSemi)

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