Remember the TM3030 uses a bridge rectifier on its power input, so it doesn't matter about
the polarity of the input voltage.
The next socket we shall wire up is the audio output. This should be a 1/4" jack socket and
you can use either plastic framed sockets (with a plastic securing nut) or ones with a metal
bush (and metal securing nut). Both types will probably have three lugs, but may have six or
just two. You will be connecting only to the terminals that will connect to the tip and sleeve of
the connected jack plug.
Connect pin 1 of AUDIO_OUT to the terminal that will connect to the tip of the jack plug.
This wire will carry the audio signal. Connect pin 2 of AUDIO_OUT to the terminal that
connects to the sleeve of the jack plug. This is the 'earth', or ground, of the signal.
Now if you have used a socket with a metal bush and securing nut and have a metal case then
the jack socket will have grounded your case. By grounding your metal case you will help
screen the internal circuitry from outside electrical interference. To help make a good
connection with the case it is best to use a toothed or sprung washer between the socket and
the inside of the case. If you have a plastic output socket do not worry you'll be grounding
your case with the midi sockets.
A close up of an older issue 1 TM3030 showing the midi connections done with Molex KK 0.1” headers
and housings. Issue 3 boards can be wired in a similar way.
Wiring the midi sockets often causes the most confusion since it's sometimes difficult to know
which pin goes to where. Midi sockets are numbered in a most confusing way. If you get this
wrong the TM3030 won't be damaged, but it will not operate correctly.
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