trouble with CM in Range

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marting
Posts: 1
Joined: Fri May 30, 2008 11:12 pm
Location: Buenos Aires, Argentina

trouble with CM in Range

Post by marting » Fri Oct 23, 2009 11:13 pm

Hello,
We are having trouble with our EEG equipment (A BioSemi 128-channels, ActiveTwo System). When we connect the A electrode set (that include the CMS/DRL electrodes) on the AD box, the CM is out of range (blue light is tilting). 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 (including or not the CMS/DRL that come with the group of A electrodes) 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) and they functioned correctly. Moreover, other sets of electrodes (for example the C electrodes) function correctly in the A socket. All these tests were done puting the electrodes on a water bucket.

Is it possible to connect the A-electrode set in any of the sockets of the AD box?
What could be happening with our equipment? Could maybe be a fault in the reference eletrodes on the A electrodes and/or its connection to the AD box? What should we do?

Any help or commentaries are welcomed

Thanks
Martin Graziano
Integrative Neuroscience Laboratory, Buenos Aires, Argentina

Coen
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Post by Coen » Mon Oct 26, 2009 2:08 pm

The described symptoms do indeed suggest a defect CMS and/or DRL in the A set. A second possibility is a defect in the AD-box (A-slot or wiring), but this is much less likely. The CMS/DRL circuitry itself should be OK, because the external CMS/DRL set works properly. Please return the A-set to BioSemi for a check and repair. Alternatively, you can also just remove the CMS and DRL wires from the set, and use the A set in the future in combination with an external CMS/DRL set (split wires as described on http://www.biosemi.com/faq/split_cables.htm, and cut off at the connector).

It is possible to test the A set (with integrated CMS/DRL) in any other slot (B-G, depending on the installed channels). However, in this case the integrated CMS/DRL will remain disconnected, and you will have to use the external (front-panel) CMS/DRL set. The B-G sets can be tested in the A slot (again with the external CMS/DRL).

Best regards, Coen (BioSemi)

loeffler.erp
Posts: 5
Joined: Mon Oct 05, 2009 4:18 pm
Location: Pittsburgh, USA

Re: trouble with CM in Range

Post by loeffler.erp » Thu Feb 18, 2010 5:54 pm

We had exactly the same trouble with the following post, and we bought a new set of electrodes (A,B,C, and D) a few month ago.

But yesterday, the same trouble happened. The Blue lights (for CMS/DRL electrodes) on the AD-box was blinking and we couldn't collect EEG data. So we tried a salt-water bucket test and the Blue light was stably on. But as soon as we put CMS/DRL electrodes to the cap of subject, the Blue light started blinking.

We also tried to put the CMS/DRL electrodes into the Gel, and at first the Blue light was on for a while, but then started blinking again. We made sure that there was enough gel and no gel-bridging between electrodes.

As our electrode sets were new and we carefully treated (we used them for 5 or 6 times only), we have been wondering what could be the reason for this problem of unstable EEG recording - it sometimes works, sometimes doesn't work.

Any kinds of your suggestions, help, and comments will be appreciated.

Thank you very much,

Naho Ichikawa

University of Pittsburgh, U.S.A.


[quote="marting"]Hello,
We are having trouble with our EEG equipment (A BioSemi 128-channels, ActiveTwo System). When we connect the A electrode set (that include the CMS/DRL electrodes) on the AD box, the CM is out of range (blue light is tilting). 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 (including or not the CMS/DRL that come with the group of A electrodes) 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) and they functioned correctly. Moreover, other sets of electrodes (for example the C electrodes) function correctly in the A socket. All these tests were done puting the electrodes on a water bucket.

Is it possible to connect the A-electrode set in any of the sockets of the AD box?
What could be happening with our equipment? Could maybe be a fault in the reference eletrodes on the A electrodes and/or its connection to the AD box? What should we do?

Any help or commentaries are welcomed

Thanks
Martin Graziano
Integrative Neuroscience Laboratory, Buenos Aires, Argentina[/quote]

Coen
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Joined: Fri Mar 26, 2004 7:00 pm
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Post by Coen » Thu Feb 18, 2010 6:14 pm

The problem is almost surely caused by a kinked cable. One of the conductors in the cables is broken, and has an intermittent contact when the cable flexes. The problem electrode can be found with the salt water test, in combination with bending and moving the cables (to determine the intermittent contact).

Start with only the CMS/DRL, then add the other electrodes to the water bucket.

Best regards, Coen (BioSemi)

loeffler.erp
Posts: 5
Joined: Mon Oct 05, 2009 4:18 pm
Location: Pittsburgh, USA

Post by loeffler.erp » Fri Feb 19, 2010 12:24 am

Thank you very much for your very quick help!

We checked all the electrodes and found that two of EX electrodes cause the blue light blinking. Now, it makes complete sense because we only bought new A,B,C,D and CMS/DRL electrodes, and kept using old EX1-8 electrodes.

We really appreciate for this and we can keep experiments without caring the temper of electrodes.

Sincerely,

Naho Ichikawa

University of Pittsburgh, USA.

loeffler.erp
Posts: 5
Joined: Mon Oct 05, 2009 4:18 pm
Location: Pittsburgh, USA

Blue light is blinking with all new sets of electrodes

Post by loeffler.erp » Wed Apr 07, 2010 2:56 pm

Hello,

We bought all new sets of electrodes a few month ago, and they were working fine for a while (one experiment per week or so). But since a few weeks ago, we have got the same problem that blue light starts to keep blinking and we couldn't collect any data...

As the electrodes are pretty new, we were wondering if it is better to send the AD-box to the company to fix it, or it can still be because of those new electrodes that we bought a few month ago.


Malfunction condition:
Random electrodes seem to set the blue light flashing. We think the
problem is in the AD box because we just bought all new sets of electrodes in a few month ago (As, Bs, Cs, and Ds including CMS/DRL electrodes attached to As).

> We did a salt-water bucket test. The following is the report (Apr 6th, 2010)
...So I have some bad news. I ran a few electrode tests this morning. I started with the As, everything was going well. As soon as I put in the Bs, blue light flashing. So I plugged the Cs into the Bs spot and the Cs worked. I plugged the Cs into the C spot and continued to put the C electrodes in the water one by one. Occasionally the system would be set off and I would have to take them out, dry them off, and start over again. I managed to get all the Cs in the water with everything working, but then the same thing would happen with the Ds. The blue light would flash and I would have to dry them off and start over again. I think the problem is probably in the box? It didn't seem like a particular electrode or even a particular set of electrodes.
--------------------------------------------------------------------------

We would greatly appreciate your help and advice.

Sincerely,
Naho Ichikawa

University of Pittsburgh

Coen
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Post by Coen » Wed Apr 07, 2010 5:00 pm

Apparently, your A set is good. Test the A set in connectors A, B, C and D. If this works, then the AD-box is OK (defects to the AD-box are extremely rare). Sent your electrode set to your local representative for checking and repair, and contact him directly (not via the forum) if the problems show up again.

Best regards, Coen (BioSemi)

fernandapgj
Posts: 3
Joined: Mon May 25, 2015 3:18 pm

Re: trouble with CM in Range

Post by fernandapgj » Tue Nov 17, 2015 8:07 pm

Hello.
My team and I are having the following problem while using our 64 electrode BIOSEMI recording system:

As stated on previous messages in this thread, whenever we connect our A branch, the blue light starts blinking. When doing the saline water bucket test, we got it steady for a few seconds but then it blinked again, at first it would blink when we put ANY other electrode in the bucket and then just by slightly moving the reference electrodes inside the bucket. We managed to get the blue light steady when pressing gently on certain spots of the A branch wires but it would not stay that way for long. When connecting the external CMS/DRL cable, the blue light continued to blink until we plugged the A branch in the C slot.
After reading this thread, I suppose the problem is in the reference electrodes of the A branch. This has happened to us before, our solution was to buy a new A-branch and the two extra reference electrodes just in case. But now I realize that the external CMS/DRL do not work if the A branch is faulty. Am I right? If so, what's the point of having extra reference electrodes?

Today, while trying to run an experiment with the temporary solution ( connecting the A branch in the C slot using the accessory reference electrodes), it worked for a while and then the blue light started blinking again.

I have some questions: 1) What is the most likely cause of the problem? 2) If I send my faulty branches to my local representative, will they fix it? I bought this branch no longer than 3 months ago. 2) Is there any provisional solution I can try to keep running my experiments before I get a new electrode branch?

Thank you,

Fernanda Perez Gay Juarez, MD
PhD Candidate, McGill University,
Post-doctoral fellow, UQAM.
Montreal, Quebec, Canada

Coen
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Re: trouble with CM in Range

Post by Coen » Tue Nov 17, 2015 9:49 pm

The symptoms suggest a damaged cable isolation (may even be a pinhole). The broken isolation causes a current path between the conductor and the water or electrode-gel.

If you can find the defect spot, then you can temporary work with the set by making sure no current can flow (improvise with tape and keep the spot free of sweat and gel).

Send the set to your local representative for checking. Durable repair of damaged isolation is usually impossible, but it is still worth checking whether this is the lucky exception.

Best regards, Coen (BioSemi)

fernandapgj
Posts: 3
Joined: Mon May 25, 2015 3:18 pm

Re: trouble with CM in Range

Post by fernandapgj » Wed Nov 18, 2015 5:10 pm

Thank you for your prompt response.

I ran the saline water bucket test yesterday and found some faulty electrodes: the two reference electrodes and A27 for branch A, and B3, B17 AND B29 for branch B.
Using the accessory CMS/DRL cable and leaving the afore-mentioned electrodes out of the water, the blue light stayed on. However, this happened only with the A branch connected in the C slot.

So, I'm guessing that the pinhole/damaged isolation is on branch A, in addition to the faulty electrodes? Is this the reason I cannot plug it on branch A? And how come it works when I plug it in C?

Sorry for all the questions, but I'm trying to understand the system and how to temporarily fix it when it doesn't work.

Thanks,

Fernanda

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Re: trouble with CM in Range

Post by Coen » Thu Nov 19, 2015 12:00 am

The cable isolation suggestion was based on your remark that any of the electrodes caused the blinking. When specific electrodes cause blinking, then these electrodes have broken conductors in the wires.

Please sent your sets to your local representative for inspection.

You can not use a set with integrated CMS/DRL in the A slot in combination with the front-panel CMS/DRL (two CMS/DRL sets connected simultaneously cause blinking). In the B-H slots, the CMS/DRL pins are left unconnected.

Best regards, Coen (BioSemi)

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