2 electrodes suddenly bad

[techmemorylab]

Hello, in between 2 subjects today, 2 pin type electrodes went bad, such that it's not possible to collect any data (CMS/DRL out of range). The bucket test showed T8 and P8 caused the out of range problem. Are these 2 electrode pins also next to one another in the connector? These electrodes were noise free during this morning's subject and now causing an electrical problem. None in my lab remember any metal touching the electrodes or any other damage. Any ideas? Thanks, Audrey

[Coen]

Pollution of the electrode tips with non-silver metal causes extra noise, but cannot cause a "CM out of range" error.

"CM out of range" problems are caused by defect electrodes. The most common cause are broken conductors in the electrode cables. The defects are caused by excessive kinking of the wires. When the break is near the electrode, then we can repair the set (mount a new electrode on the shortened cable).

A set with defect electrodes can be used temporary for measurements, provided that the defect electrodes doe not make contact with the subject (there is no danger, but upon touching the safety circuits will be triggered and all electrodes will loose signal).

Best regards, Coen (BioSemi)

[Baris]

Hi Coen,

We also had a similar problem yesterday that when we plugged the CPz electrode into its slot all the electrode recordings went crazy, but when it was out of its hole everything was fine. Is this because of the excessive kinking and the electrode is dead? If so, what is the electronics explanation of this phenomenon, when the electrode is not in the electrode slot there is no problem but when it is plugged into its hole there is a problem?

I wonder how much you charge for fixing this problem.

Thank you,
Baris

[Coen]

When one of the conductors in the cable is broken due to excessive kinking, then the input of the active electrode is not biased in reverse anymore. This may cause small current flow between subject and the defect active electrode. This abnormal current flow is detected by the ActiveTwo safety circuitry, and the power supply to all active electrodes is shut down. This condition is indicated by a flashing blue light.

Unplugging the defect electrode breaks the path for the fault current, and normal operation is restored (provided all other electrodes are working properly). The absence of a fault condition is indicated by a solid blue light.

Replacement of a single active electrode is priced at EUR 40 (pin type) or EUR 50 (flat-type), plus shipping.

Best regards, Coen (BioSemi)

[Baris]

Hi Coen,

We have two electrodes, each showing kinking problem on each bundle.
So I need to to send the two bundles for repair. Where should I send it?

Best,
Baris

[Coen]

http://www.biosemi.com/contact.htm

[Baris]

Do you send an invoice and can the University pay it later?
Best,
Baris

[Coen]

Yes, unless we decide that it's a warranty case.

[Baris]

Hi Coen,

I am shipping the bundles today and the package will arrive Amsterdam on Friday. We detected that CPz and T8 electrodes show the problem, but it would be great if you can double check all the electrodes beforehand to make sure. We are open to any suggestions, for instance let us know if there are some other electrodes which may need to be fixed (or you recommend that they should be fixed)

Shall I also drop an e-mail to another person or could you forward this e-mail to the repairs department. I did not put any letter or any notes in the shipment box.

Thanks,
Baris Demiral
Department of Psychology
7 George Square
University of Edinburgh
EH89JZ Edinburgh
UK
demiral.007@gmail.com

[Coen]

It is not very clever to not put any note in the box. How you expect our repair people to trace the history and return address for the sets ?