User manual

the machine reliably for 3 or 4 hours. Some machines may be more robust and others

more flaky – depending on how fussy the CPU chip is. After these changes, I expect

machines should run for 5 or 6 hours before the battery voltage falls to the point where

the CPU may malfunction. These times are not guaranteed. The actual running times

depend on the batteries, the temperature, what the Devil Fish is doing, and especially on

the characteristics of the particular CPU chip.

When the on-load voltage of the 4 cells combined dropped below about 5.5 volts (1.375

volts / cell), the TB-303’s CPU chip would generally be running from 4.5 volts or less.

The CPU chips are only specified to run from 4.5 to 5.5 volts, so if they malfunction

below 4.5 volts, it would not be surprising. Each individual CPU has its own lower limit,

and this may vary with temperature. The lower limit for proper operation may also rise

with age. I have seen particular TB-303s or Devil Fishes become more fussy about

supply voltage. This is not common, but it may happen to any machine. Replacement

CPU chips are now available, due to them being removed for installation of the

Quicksilver 303 system. The failure mode may be the CPU freezing – so there will be no

sequencer or front panel activity. Another failure mode may be it stepping through a

pattern, displaying things on the front panel etc, but failing to trigger the Gate of the

synthesiser – so no sound is played and no Devil Fish LEDs are turned on.

The Version 4.0C changes reduce the voltage drop to the CPU and so enable any given

CPU to operate at correspondingly lower battery (or external supply) voltages. I estimate

the voltage at the batteries which is required for 4.5 volts to the CPU is reduced from 5.5

volts to about 5.05 volts. This means that the machine will run properly for longer on a

particular set of C-cells.

With Version 4.2B (February 2015) and for any earlier machines which we do further

work on and send overseas, we install an under-voltage protection system so the machine

is not powered at all if the battery or external power supply voltage (after passing though

the internal regulator, which attempts to drop it to 6.0 volts) drops below about 5.0 volts.

This is to prevent the C-cell batteries from being flattened if the machine is left running

from these batteries for a long time. This reduces the chance of the C-cell batteries

leaking, and should ensure they retain enough charge to retain the memory data. For a

full description of this, please see the separate manual DF-Memory-Backup.pdf.

Please see the discussion below (Known reliability problems) on how the Run/Stop LED

is an indicator of power supply voltage. A dim Run/Stop LED indicates that the battery

or external power supply voltage is too low.

Power Adaptors

The Devil Fish with MIDI In or MIDI In and Out and the headphone amp operating,

draws 180 mA from the external power adaptor. The lowest current drawn, with few

LEDs on and no sequencer, synthesiser, headphone out or MIDI activity is around 150

mA. It is vital that the power adaptor used for the Devil Fish (or any TB-303 or TR-606)

be an independent adaptor for this machine alone, and that it be close to 9 volts. 8.5 to 9.5

volts is best.

Until about 2011 I recommended a Boss PSA-240 adaptor for Australia. I similar adaptor

could probably be found for various countries depending on the supply voltage: PSA-100,

PSA-120, PSA-230 etc. These put out a reliable 9 volts with quite sufficient current for