User manual

when the mains voltage is rather low (say 110V or 220V AC) then the same power

supply, when cool, unloaded and running from a higher mains voltage (120 volts or

greater than 240 volts) is bound to put out significantly more than 9 volts. The question

is: what voltage is the adaptor putting out in practice, when loaded by the Devil Fish? 10

or perhaps 11 volts is probably OK. Anything above this risks overheating Q45, and so

causing damage soon or in the long-term. This is a general problem for TB-303s and all

similar machines which run from a power adaptor. I don’t know of a specific instance of

a Devil Fish being damaged in this way, but I wouldn’t be surprised if it occurred.

There is no rule which enables users to choose their external supplies with bullet-proof

safety. In general, stick to Boss or other quality Japanese adaptors which are 9 volt DC,

and which have a current rating between 150 and 500 mA. If in doubt, have a technician

check the voltage of your adaptor when it is operating the Devil Fish. The easiest

approach to this is to take the back off the machine and use a volt meter on the circuit

board where the power jack is mounted.

Tact switches and pots

Until mid-2010 I replaced the tact switches (the 24 click switches behind the silver

buttons) with the original type: ALPS SKHCAA (now known as SKHCBEA010), with a

flexible plastic dust-guard, which greatly prolonged their life. Dust (mainly flakes of

skin) gets into these original switches and builds up on the contact points, making the

switches unreliable. Then the switches “bounce” – meaning they either don’t work, or

turn on and off several times, when pressed and released once.

From mid-2010, we are installing Omron B3W-4050 sealed tact switches. These should

be impervious to dust and liquids indefinitely, so hopefully they will work for many

decades without bouncing. The stems of the switches don’t quite fit the TB-303 buttons.

So I cut two slots in a cross formation into the stems, so it becomes four separately

sprung segments, which bend slightly to fit the buttons.

These Omron switches are slightly firmer than the originals and have a good click action.

They may not hold the buttons in as exact a rotational alignment as the original ALPS

switches, so if the buttons are slightly clockwise or anti-clockwise, it would be due to the

Omron switches not having such tight rotational registration. These Omron switches feel

good and appear to be the best way of ensuring long switch life. An ALPS sealed tact

switch (SKQEAAA010) is available, but it has a high activation force, little travel, little

difference between the activation and holding forces and therefore a poor click action.

Tact switches which are erratic make the machine difficult or impossible to program.

There is no way of repairing them or improving them by spraying stuff (oil or anything

which comes in a can which claims to fix electrical problems . . .) inside them. In my

view, stuff should never be sprayed inside anything electronic, unless the component is

able to be dismantled and the cleaning done with isopropyl alcohol in a manner that it can

be completely cleaned off and then visually inspected. These tact switches cannot be

dismantled or improved with any such liquids.