And yet another, another weird corrosion story (not synth rel ated)

[Curtin, Steven D (Steven)]

A friend's son had a ZOOM guitar effects pedal that had started to act
strangely, such as not working with certain programs and outputting a
repetitive signal on others.  I took a look at the PCB and there was the
same kind of stuff you see on a corroded battery all over the pins for the
A/D and D/A parts.  This came off with alcohol but the problem came back
soon.  People familiar with cellular phone designs here say this is a common
problem as well, somehow the continuous voltage on these pins attracts this
stuff.  

The inside of the ZOOM pedal was really amazing- not a single off the shelf
part on there and all surface mount.  The pedal part of it worked by using a
single LED emitter-sensor, with a silver sticker on the pedal that changed
the angle of reflection from the emitter back to the sensor.  Neat idea.

Steve C

-----------------------------------------------------------------
Steven Curtin  
Lucent Technologies Microelectronics
ph: (732)949-4404   fax: (732)949-6711
http://curtin.emf.org
sdcurtin at lucent.com
-----------------------------------------------------------------


> ----------
> From: 	IXQY at aol.com[SMTP:IXQY at aol.com]
> Sent: 	Tuesday, September 26, 2000 4:19 AM
> To: 	synth-diy at node12b53.a2000.nl
> Subject: 	And yet another, another weird corrosion story (not synth
> related)
> 
> 
>  Well, maybe not a corrosion story but perhaps the beginning of one?
> 
>  Back in the late 70's, my parents kept a metal flashlight on top of the 
> refrigerator. I reached for it once and found that it was very very hot.
> The 
> top of the fridge was warm, but the flashlight was "hot", so I don't think
> it 
> had anything to do with the fridge. 
> 
>  After taking the flashlight apart, I found that the batteries (two C or D
> 
> cells) had leaked and were also very hot. I asked my high school
> electronics 
> teacher about this after it happened and his explanation was that the
> battery 
> acid probably had a chemical reaction with the ink on the battery label.
>  
>  Would this be a a correct assumption?
> 
>  Thanks, I've always wondered about this....
>  Andrew Sanchez
> 
> 
> 
>