Roland TB-303

via this auction

"* Auction includes: Roland TB-303 with replaced Alps pushbutton switches, dust guard installed and upper six knobs remounted about 1.5mm higher
* Original Roland grey & orange faux leather carry case / gig bag
* Bound copy of the TB-303 manual
* Choice of official Roland/Boss power supply (choice from Boss models PSA-240 (brand new and made in China), PSA-220, ACA-120G and ACA-220 (the latter three being used and all being made in Japan)
* Energizer Ultra C cell batteries x4

I acquired this TB-303 from a small private UK based studio in January 2004. I assume it belonged to an ex guitar player or pub singer etc. who had perhaps had a tinker with it sometime in the eighties then swiftly relegated it to a dusty shoe box under the bed where it probably sat till it came to me. The reason I say this is that the tell tale signs of heavily used TB-303’s are the paint markings around the upper six pots, particularly the freq. cut off and resonance ones, being worn off. On this TB, there are no such signs at all; in fact the general paintwork is excellent, bar a few small blemishes that I highlight in the pictures below. A quick test back in 2004 revealed it to be in fine working condition, and re-plugging it in 7 years later, things were no different, however clearly the dust had taken its toll on the pushbutton switches that occupy the lower half of the 303, for many of them were bouncing or double triggering; a very common situation with 303’s. These switches are manufactured by a famous Japanese company called Alps and are of excellent quality, however they are an open (i.e. unsealed) design and therefore are very susceptible to contamination. If you read Robin Whittle’s site here then you’ll note that his view is that over time, flakes of skin get into the switches and this then leads to intermittent contact when the switches are depressed by the user. Believe me – this phenomena can drive you crazy! The 303 is quite arcane enough to program without any annoying distractions. If you’d like to see how it can detract from your workflow, check out this YouTube video.

So the first thing I addressed is replacing these switches – amazingly they’re still manufactured by Alps. Availability in the UK has been a bit of an issue, however they were always quite readily available in the US. But they have been recently discontinued so I had to pull some strings to get my set of 24 for this machine :-) So just to say again, these are the exact same Alps manufactured switches, the only difference being that they are new! I have replaced switches on TBs many times so know the drill quite well, first job was to desolder and remove the old ones, next I clean the PCB of dust and dirt (much easier to do once the switches have been removed) and then I solder in the new switches. There are pictures of the process below. And that was the only replacement this TB warranted, the rest of my TLC was in the shape of some fiddly cleaning work across the main PCB using a set of cotton wool buds dipped in mildly soapy water, and then pure water. This is time consuming, but I always like the idea of removing 30 years worth of grime while I have the hood popped, so to speak.

Robin Whittle of Devilfish fame implements a nice simple idea to prolong the life of the pushbutton switches, he makes a dust guard from overhead transparency film. It just so happened that I had a spare so I decided to put it to good use inside this TB. I also implemented another practical, simple and very useful non electronic modification which was to cut some small pieces of rubber to lift the height of the upper six potentiometers by about 1.5mm. This makes them a lot easier to turn. And before the knob and switch tops were put back, I decided to give them a nice bath in soapy water then a scrub with a toothbrush, also ridding them of 30 years worth of gunk.

That done, it was time to screw it all back together again, flick the power to on for a quick test, which I always look forward to because, as you may know already, while each TB speaks the same bubbly, chirping and gurgling language, due to loose component tolerances back in the eighties (as much as 100% for say, electrolytic capacitors compared to 10-20% today) they tend to have subtly distinctive voices, with no two ever sounding quite the same. Some are more bubbly, while others tend to scream more. I have also had TB’s that have a lazy slide implementation and others that are faster and so that distinctive 303 ‘mid air’ shift is not quite so obvious. No matter what the voice, they’re always to my taste, they just appeal in different ways. Anyway this TB seems a bit of a livewire, but don’t take my word for it, there’s a YouTube video to look forward to, but first, some pictures....

One thing worthy of mention, as this pic attests, this TB has a very clean battery compartment and so it appears it was not previously stored with batteries inside. Most TBs were and the tell tale signs are nasty battery acid leak stains and the subsequent corrosive atmosphere leading to some of the IC pins corroding. I am pleased to say there are no such nasties on this TB.

Another thing worthy of mention is the power supply, TB’s feed off of 9 volts and this is delivered by a ‘Boss’ branded ‘wallwart’ / adaptor style power supply. The Boss ones are of excellent quality, being regulated (meaning the supply of 9V at max. 200 milliamps remains constant irrespective of fluctuations with the ~ 240V ac coming in through the mains), however for reasons that escape me, in lieu of the Boss type, many people seem to use their TB’s with cheap, poor quality adaptors that are probably putting out significantly more than 9V. There are even simple but important details to observe such as the TB’s power tip being centre negative. I think we can agree it is most probably best to stick to the Boss original type and this TB will come with a brand new Boss model PSA-240 power supply"









YouTube via prestopatch — April 06, 2010 — TB-303 up for auction from 08/04/2010 - 18/04/2010