User manual

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Small pots and toggleswitches in the Devil Fish board
There have never been any problems with the seven beautiful little ALPS pots used in the
Devil Fish. Likewise the C&K 8125 switches used beneath the Accent button (and in
the memory system) seem to last forever, unless something smashes against the button.
There have never been any failures of the 6mm sockets used in the TB-303 (Filter In,
Filter Out/FM and Audio Out) – these are remarkably reliable sockets. There have never
been any failures of the 3.5 mm sockets of the TB-303 (CV and Gate Out). The only
problem with the Devil Fish 3.5 mm jacks is discussed in a section above on the Gate In
socket
There is a lifetime “wear out” problem with the three three-position toggle-switches used
in the Devil Fish panel. These are of the highest quality, and are made by only one
manufacturer: C&K. They are a T211 SHCQE. Their three-position operation depends
on the interaction of a small piece of fibreglass-reinforced plastic with the sides of the
case, which is made of a similar material. With a lot of use, the sides of the moving
plastic piece become rounded from friction against the case. The result is that there is
progressively less of a clear distinction between the three positions. There still are three
positions, so the switch remains electrically fully functional, but it does not have its
original clear positive tactile action. I haven’t tested this to find out how many hundreds
or thousands of operations cause a deterioration. I encourage users not to flick these
switches back and forth for no good purpose. Repairing the problem is non-trivial.
One approach is not to de-solder the switch, but to leave its base intact on the circuit
board, and to unclip the metal part. A new toggle, metal surround and internal contacts
and plastic piece can then be clipped to the switch base. Of course this involves complete
disassembly and re-assembly of the Devil Fish, which is not for the faint hearted.
However, some of the wear occurs in the outer case, so to replace the switch fully, the
case and contacts must be removed. I suggest clipping away at the plastic case to remove
most of it, so the pins can be pulled out individually. Then use a solder sucker on the
holes and install a fresh switch.
Replacements for the 6 small TB-303 pots
Technology Transplant ( www.technologytransplant.com ) sell replacement pots for
the 6 small pots along the top of the TB-303. (They also sell replacement Tempo and
Volume pots.) There have been several versions of these pots over the years. In March
2006 I received some and when I first used a set in August I found that the Resonance pot
is not a linear pot, as it should be. The Resonance pot is a dual 50k pot, with a linear
taper, which is ‘B’ in the arcane world of potentiometer nomenclature. So “50KB” is the
label of the original and the replacement pots. The Resonance pots I received concentrate
most of their resistance variation into the centre of the rotational range. That is to say that
very little happens between fully anticlockwise and about 10 o’clock, and likewise very
little happens from clockwise back to about 2 o’clock. This could be thought of as being
“log” on both ends. They are labelled ‘A’, which normally means log – specifically
logarithmic so little change happens when starting from the anti-clockwise position, with
the mid-resistance point usually being beyond the mechanical centre point.
This is a minor problem of little concern, since it doesn’t alter the range of sounds which
are available. It should be borne in mind when writing down knob settings, and
transferring them to another machine with the original type of Resonance pot. Despite