CMS/DRL out of Range set A

[felsenhe]

Hello,
We are having trouble with our EEG equipment (BioSemi 64-channels, ActiveTwo System), similar to others in this forum. When we connect the A electrode set on the AD box, the CM is out of range (blue light is tilting). We have an external CMS/DRL.
If we disconnect these A electrodes and connect the CMS/DRL external electrodes only, the AD box starts to function correctly. But if we connect both it doesn't work anymore (CM out of range). We also tested changing the location of the A electrodes: we connected them into another socket of the AD box (we tried with the one corresponding to the C electrodes) the CMS/DRL is in range again. However, if we put the electrodes of set A in to a water bucket test, it is again out of range. Moreover, other sets of electrodes (for example the B electrodes) function correctly in the A socket. All these tests were done putting the electrodes on a water bucket.

Any help or commentaries are welcomed

Best

[Coen]

Possible causes:

- Gel in the connector. Clean with distilled water and dry with alcohol
- Intermittent contact in one of the wires or connector. Sent electrode set to BioSemi for repair

Best regards, Coen (BioSemi)