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For some reason when ever I use the physical volume control on my Toshiba Satellite P305-S8904 laptop, it triggers the 'c' and 'b' key. So I can be writing an email and turn the volume control wheel and I will see 'c's just appear. It is particularly annoying when watching movies in VLC player because the 'c' key is responsible for image cropping.

Actually to be more precise, whenever I slide/turn the volume control to the right I will get the 'c' key but when I turn it to the left I will get mostly 'c's but sometimes 'b's.

I know it sounds like I am talking about the grades I generally get at school or that it sounds highly improbable that this is happening but, i assure you that it is in fact happening and very annoying. So the questions are:

  1. Why is this happening?
  2. How do I stop it?
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Does it change the volume? Have you installed the drivers/software for it? – Tom Wijsman Aug 4 '10 at 10:09
it actually changes the volume but in unexpected ways. sometimes when i try to decrease the volume it actually increases. when i try to increase the volume, the volume position will shake up and down very fast and slowly go up at the same time (if you can picture this). perhaps the contacts are dirty. – classer Aug 5 '10 at 16:42
up vote 2 down vote accepted

It is not that surprising, most keyboards' hardware does not contain a separate contact for each key, but is rather based on a matrix with each key triggering two contacts. In addition, the path from the keyboard to the CPUs often contains translation hardware busses (e.g. USB) etc., again, you get a mapping between keys to contacts that is not 1:1

In other words - this is almost certainly a hardware problem.

As to fixing it, if it not under warranty that would be voided, I would have tried to open the thing up and try to clean the relevant areas.

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so this is just a matter of a dirty potentiometer? or does it require re-wiring? – classer Aug 5 '10 at 16:38
My guess is that it is simply dirty, but YMMV... – Ofir Aug 8 '10 at 8:30

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