User manual

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A good adaptor will put out 9.0 to 9.5 or maybe 10 volts maximum when the Devil Fish
is running from it. If the Run/Stop LED does not light fully and without fluctuation when
the sequencer is running, then the external power adaptor (or the C-cell batteries if this is
what you are using) are not supplying sufficient voltage.
The machine may work OK with higher input voltages, for a while – but the internal
regulator transistor will be asked to drop 180 mA through more than its intended 3.0 volts
(9 volts external dropped to 6 volts internally means a 3.0 volt drop across this power
transistor and therefore a 0.54 watt dissipation). If you notice the back right of the
machine getting too hot, then you are probably driving it with an adaptor which is putting
out too high a voltage. This probably won’t damage the transistor immediately, but
extended use will damage it and make the machine unusable except from C-cell batteries.
See further discussion below in the “Q45 overheating” section of “Known Reliability
Problems”.
Do not use share one power adaptor amongst multiple machines. Theoretically it may
work if the two machines are identical, such as two TB-303s etc. However, this sharing
of 9 volt adaptors with other machines is likely to damage machines such as the TR-606
or TB-303 / Devil Fish. These use a regulator in the negative lead, so this lead drops to
-3 volts for a 9 volt input, causing the positive lead to be the +6 volts the internal power
supply requires. Most other musical instrument devices ground the negative lead – and
the TB-303 / Devil Fish will have its ground connected via audio leads to the ground of
the other device. This would bypass the TB-303’s internal regulator, and force the
positive lead to +9 volts, or whatever higher voltage the adaptor is putting out. This is
likely to damage the internal power supply and it would not be surprising if it destroyed
the CPU chip, which would then be running from 8.0 or more volts, while its absolute
maximum voltage is 6.0 and while it is only specified to operate properly on 4.5 to 5.5
volts.
Optional Headphone Output
In October 2012 I can introduced an option for a 3.5mm Headphone Socket between and
above the Power and Audio Out sockets. This is a stereo 3.5mm socket with the original
Headphone Amplifier driving both the ring (right) and tip (left) connections via their own
10 ohm resistors.
This is identical to the circuit of the original Headphone socket of the TB-303, except
that with that system, the Headphone Amplifier was only turned on when a 6.5mm plug
was inserted into the socket. With the new arrangement, the Headphone Amplifier is
turned on at all times, which adds about 17mA to the power consumption. This is around
10% of the normal current consumption.
Without this mod, I use the old Headphone Amplifier to drive the Audio Out from Filter.
The Headphone Amplifier has a 5 to 6 volt peak-to-peak output range. With this mod I
install a new amplifier for the Audio Out from Filter, with an approximately 10 volt peak-
to-peak output. So with this mod, there is a somewhat higher output level before clipping
on the Audio Out from Filter circuit.
With the new Headphone Socket, very high output levels – high signal levels in the Devil
Fish circuitry together with the Volume pot being set high – will lead to some distortion
in the Headphone output. This is the same as what would happen in an unmodified TB-
303, except that the unmodified TB-303 could not produce such high level signals.