[sdiy] TB-303 Problems and Questions

[ian taylor]

Just a thought aout the noise (2) - I've noticed on some Roland gear (notably the SH-101 but might have been the 303 as well) 
that you should really use a good PSU - Ideally something like the boss one,
as that stopped all hum when I switched from using a standard multi voltage adaptor...

> Date: Mon, 2 Aug 2010 15:51:43 +0200
> From: cheater00 at gmail.com
> To: analogue at hyperreal.org; synth-diy at dropmix.xs4all.nl; 313 at hyperreal.org
> Subject: [sdiy] TB-303 Problems and Questions
> 
> Hi guys,
> my TB-303 has some problems and I thought I would ask around if anyone
> knows how to fix them :)
> 
> 1. line output not working
> yup :( no output. There is "perfect" output from the headphones output.
> 
> 2. headphone output has a faint sound of digital buzz
> When the LEDs are blinking, I can hear a buzz when the LED is on. This
> might be the way it worked out of the box - but if so I would like to
> fix it with some mods. The sound is fairly prominent and can be heard
> when the synth is playing as well, making it useless for what I want
> to do (i.e. put the 303 stems in a mix not obscured by a lot of other
> sounds. I understand you wouldn't hear that in a very busy mix)
> 
> 3. power-on thump
> I assume this needs some replacement of the electrolytic caps, but not
> sure which ones exactly. I wouldn't want to just go wild on it and
> replace everything
> 
> 4. decay knob doesn't do anything
> No idea why. This started recently.
> 
> 5. (hopefully a mod exists for this) the filter cutoff range is too
> small. I know you can change the range around a bit with one of the
> trimpots, but that doesn't give me the needed range. I would like to
> go from around 30 Hz to 30k if possible.
> 
> 6. Potentiometers are noisy and slow, i.e. difficult to drag:
> the resonance knob is especially slow! The others feel a bit wonky too
> and are probably quite worn. Is there a good replacement?
> 
> 7. Waveform switch is wonky and sometimes doesn't close contact properly
> is there a direct replacement part - or do I need to open it up and
> recondition it? I would really like to avoid that :X
> 
> BTW, is there a mod to change patterns in write mode?
> 
> Thanks a lot,
> D.
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