Parts removed, device still works

A project log for Digitech GE-4059 hacking

Turning a broken-down el'cheapo USB turntable into a useful USB audio input device

Stuart LonglandStuart Longland 01/13/2018 at 08:320 Comments

So last Wednesday night, I was over at HSBNE… I deliberately brought this little device, my laptop, my turntable and a couple of records.

First step was to remove C16 and C29.  The hot air re-work station did a good job of that.  I plugged the slightly modified device into the turntable and laptop, fired up Audacity and ran a test.  Yep, still getting audio through.  So off came the remaining parts.

I'm still undecided as to whether to expose the GPIOs or not.  It'd be a pain to solder to those pins on the chip and to be honest, I'm not sure if they'll be useful or not.  Most software I'd use with this device can't make use of the GPIOs directly.

Having removed the remaining parts, I was able to digitise one of my records, stashing the recording for later listening.  The removal of the pre-amp means it's no longer there to create noise.  I took the now useless 2.54mm JSTs off, since I have the mating connectors for those, they can go into the junk box for another project now, as have the two electrolytic capacitors.

I'll have to find a suitable case to mount it all in, but in all, this is practically done.

One artefact of my current turntable I'll have to ponder is some speed correction.  The player has no speed adjust beyond a selector switch for 33⅓ and 45 RPM.  Unfortunately, what it calls 33⅓ is more like 34⅘ RPM.  For now, putting up with it playing a little fast during the recording session and doing a speed correction in Audacity works, but long term, I'd like to fix that on the turntable.  But that'll be another project.