User manual

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The sockets I use seem to be robust and have plenty of spring-pressure on the contacts. I
don’t know of any other “better” sockets and the problem is so rare I cannot reproduce it
– so I have no means of being sure I have entirely eradicating it. The problem is
occasional, since there have been only a few reports from users and one instance with a
newly modified Devil Fish I was testing.
Starting with serial number 084 (13 April 2000) I bent the fixed contact of the CV In
sockets a little to increase the pressure the spring contact makes on it. This may improve
reliability. I only know of one instance, a 2002 modified machine in 2010, where this
problem occurred on a machine with these specially bent socket contacts. Microscopical
examination of the faulty contacts is consistent with “fretting corrosion” – localised
oxidation caused by slight movement between the contacting surfaces. This CV Input
socket had been used frequently, so the surfaces would have touched and moved with
respect to each other each time a plug was inserted or removed.
32 Bank Memory system – problems when fresh C-cell batteries are installed
This problem affected the first 32 Bank Memory systems, from July 1999 to March 2000.
Please see the separate manual DF-Memory-Backup.pdf for details.
Q45 overheating
This is not a problem for the Devil Fish as such, but a general problem with TB-303s and
other devices operating from AC adaptors.
A common problem for TB-303s and I assume Devil Fishes is that the machine is
sometimes connected to an AC adaptor or to a DC adaptor which produces significantly
more than the required 9 volts. The machine my run properly, but the main regulator
transistor in the internal power supply section – Q45 (type 2SB569) – can become
overheated. Over time, this may damage the transistor and it may fail completely, or
more likely fail to operate properly. You may be able to feel this overheating in the rear
right of the machine. Damaged transistors typically show discolouration of the green
plastic case and plated copper heatsink. Some are remarkably resilient, operating
correctly despite having their plastic and heatsink blackened and even showing blobs of
solder leaking from within the transistor itself! I replace the “B569” with a commonly
available transistor called a “TIP30”, but not all of them have sufficient gain to operate
correctly. As is often the case with electronics, many weird and wonderful fault
conditions turn out to be caused by inadequate supply voltage, or a faulty power supply.
Generally the Roland or Boss adaptors are fine. Cheaper adaptors may say something
like “9 volts 400 mA”. This means they are supposedly capable of producing 400 mA of
current (milliamps are like pints of water per minute flowing through a pipe) whilst still
maintaining a 9 volt (volts are like pounds-per-square-inch of pressure in a water pipe)
output. The Devil Fish uses around 85 mA in idle mode and no more than 155 mA when
running. The latter figure includes 15 mA drawn by the old headphone amp if a plug is
inserted into the socket which is not Filter Out and Filter FM In. Most power adaptors do
not have internal regulators. Their output results from a transformer secondary winding
going through some silicon diodes and being smoothed by a capacitor. To achieve a
minimum voltage of 9 volts (not the average, the minimum after allowing for the 100 or
120 Hz hum variation as the mains charges the capacitor in pulses) at maximum output
current (say 400 mA) when the transformer’s windings are hot and have a high resistance,