Cyclone Analogic Bass Bot Bedienungsanleitung PDF herunterladen (Seite 13)

higher), then if the capacitor is not being driven via the internal diodes from the main power supply, or by

the C-cell or the coin cell batteries, then connecting it to the capacitor for will drop its voltage by about 15

parts per million per second. It only takes a few seconds to connect the meter, record your measurement and

disconnect it. For instance, at 4.0 volts, a 5 second measurement will drop the voltage by 4 * 15 * 5 = 300

microvolts = 0.0003 volts.

Testing the VRAM current

To measure the current drain from the C-cell batteries to the memory backup system (the memory chips, the

chip-enable decoder chip, the original 100uF capacitor and the new 6,800 uF capacitor and any other source

of leakage) disconnect any power adaptor and run a microampmeter in series with a silicon diode, such as a

1N4148 between the positive C-cell battery contact and the abovementioned VRAM test terminal. Please

allow a few minutes for voltages and currents to settle. The current should be below 1uA.

There are two 1N4148s in series inside the machine between these two points, due to the potentially high

voltage of four fresh alkaline C-cells in series driving VRAM higher than the 5.5V operating limit of the

memory chips. The microampmeter in series with a single 1N4148 diode will raise VRAM 0.5 to 0.6 volts

higher than normal, so the current you measure will be slightly higher than during normal operation (the C-

cells powering the memory system when the machine is turned off). It will also be significantly higher then

the current drawn by the memory system from the optional internal lithium battery alone (when the machine

is turned off and there are no C-cells installed) since the lithium battery is typically 3.0 to 3.3 volts. A single

1N4148 diode is between the lithium battery positive terminal and VRAM, so he highest VRAM voltage

when powered by the lithium battery is likely to be 2.5 to 2.8 volts, rather than the approximately 5.5 volts

which might be present on VRAM with fresh C-cells and the ~1.0 volt drop of the two diodes.

Deliberately zeroing VRAM to erase the memory contents

In the original TB-303, it was possible to remove the C-cell batteries, wait a few days, or perhaps weeks, and

then power the machine on again, to find that the stored patterns and tracks have been either corrupted or

erased. To perform the same operation with a machine with Option B or C, you must disconnect the

machine from its external power adaptor and remove the C-cell batteries. There is no need to remove the

coin-cell lithium battery, since excessive current drain on this battery is prevented by a 100 ohm resistor.

Short the VRAM wire mentioned in the previous section to ground. It is probably OK to do this with a wire

with close to zero ohms resistance, but don't be surprised if you see a small spark. A more civilised method

involves using a 10 ohm resistor in series with the lead, to reduce the current spike.

5 - Option C - C-cells with under-voltage protection, large capacitor and a

replaceable lithium coin-cell battery already installed

This is the same as Option B, except that for customers in Australia, we will install a 2032 battery, and ship

the machine to the customer via road, using Australia Post.

There is no need to keep C-cells in the machine in order to retain the memory contents.

Please refer to the section above regarding Option B for when and how to test the battery's voltage, or to

replace it.

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Cyclone Analogic Bass Bot Bedienungsanleitung Seite 13