5
1 - If the machine was left running from batteries for too long, the voltage would
drop so far that firstly memory data would be lost and secondly, over time, the
batteries would leak their electrolyte, causing corrosion to the battery contacts and
perhaps to the circuitry itself.
Alkaline batteries have lower self-discharge rates, larger capacities and are less
likely to leak. Do not use ordinary (carbon-zinc) C-cells. Always use alkaline
C-cells.
2 - Memory contents rely on the batteries having sufficient charge, and making good
contact with both the positive and negative contacts.
The negative (coil spring) contact cannot be seen unless the machine is
dismantled, so the user may not notice corrosion there.
The positive contact may have corrosion, and so make poor contact.
On older TB-303s, the positive contact is recessed so far that modern batteries (of
the 1990s and later) do not touch it, due to these batteries having their positive
terminal protrude very little, compared to what was common in the early 1980s,
when carbon-zinc batteries were most common. (We fix this as part of the Devil
Fish mods.)
3 - The user had to keep C-cell batteries in the machine at all times, except for
perhaps a few minutes (or in practice perhaps a few days) when removing one set
and installing a fresh set.
This leaves the machine at continual risk of being turned on and running from
batteries by accident, which leads to the danger of data loss and corrosion of
battery contacts and the internal circuitry.
The solution I adopted, in 1996, for Devil Fishes version 2 and above, is described in the next section:
Option A – a permanently installed large capacity lithium battery.
3 - Option A - Permanently installed cylindrical lithium battery
All version 2.x, 3.x, 4.0, 4.1, 4.2 and 4.2A Devil Fishes, except those with a Quicksilver 303 system, had a
large capacity cylindrical lithium battery installed as part of the Devil Fish modifications. This is the Devil
Fishes which were first modified from 2006 to the end of 2014, and a single machine (serial number 287) for
an Australian customer in January 2015.
This battery may not be retained in the future. If we work on one of these machines and return it to a
customer overseas, we will remove this battery and install the Option B system mentioned in the next
section.
The battery is a Varta CR 1/2 AA, which is a 3 volt cell rated at 950 milliamp hours. It is the same diameter
as an AA pen cell, but half the length. It has a stiff copper lead welded on each end, and with these leads the
battery is soldered to the main Devil Fish circuit board. The Material Safety Data Sheets at varta-
microbattery.com state that these contain 0.3 grams of metallic lithium.
(28 paginas)
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