[sdiy] Gibson Robot Guitar teardown

[johnspeth at yahoo.com]

Hi group-

I was privileged to attend the Embedded Systems Conference in San Jose this week.  Yesterday they did a live teardown of the Gibson Robot Guitar, a Les Paul with automatic tuning.  It was worth relating what I saw:

So you just spent $2500 on a Les Paul.  If you're like me, you're ultra curious about how it works but risking voiding your warranty keeps that knowledge bottled up.  It was a rare occasion to see somebody else take that risk.

Gibson did a great job of preserving the integrity of the Les Paul.  You could remove the auto-tune stuff and you'd still have a true-blue Les Paul without any extra holes, cavities, or anything.

There is a one knob module with a battery that is recharged with a special external guitar cable device.  The module takes the place of one of the volume pots.  In that module is a C8051F120 that handles the UI (a terribly overloaded knob with only push and turn capability), string frequency measurement, and tuning peg motor control.  The module contains power supply, battery charging, a CAN comm chip, and analog interface circutry.  String frequency is measured by 6 piezo devices in a special bridge connected to the knob module with a flex ribbon cable.

On to the head.  The strings provide a method to provide power and redundant communication to the motors and controller on the head.  A special string tail price provides the necessary insulation to avoid shorts.  Obviously, the frets will bypass that system.  Each tuning peg has a tiny stepper motor, a tiny closed drive reducer, and a main drive gear that can be engaged/disengaged by the user per tuning peg.  All six tuning pags are driven by a stepper motor controller module centered around another C8051F120.  Communication is via CAN (automotive!).  

Here's the zinger: The stepper motor and drive reducer is coupled with a rubber belt!!  Talk about weak links!  It's been my experience that rubber cracks with heat, it will eventually stretch to a permanant oversized shape, and with time will someday turn to goo.  If you're gonna buy this guitar, buy a lifetime supply of belts and freeze them for later use.

See more at: http://www.eetimes.com/galleries/slideShow.jhtml?galleryID=11&imageID=1

JJS


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