Midi, Power and Audio Connections
The original issue 1 prototype had its input and output sockets mounted on to the PCB itself.
This initially seemed quite practical, but in reality would only be useful if everyone was going
to be using the same casing as me. In the production runs of the PCB I have used 0.1" headers
for all the I/O connections. This should give you more flexibility in making your unit suit your
own needs. The TM3030 board will be held in place in the case either by the pot brackets or
the four mounting posts, or even a mixture of the two. The sockets should then be mounted
onto the rear panel and then hand wired to the PCB.
0.1" headers are commonplace on commercial units to speed up manufacture. You can use
either Molex [strip and crimp] or MTA [insulation displacement] type connectors. For those
who haven't a clue about either of these forms, it is probably best for you to just to solder the
connecting wires in place. 0.1" headers are useful and easy to use, but both types require
special and relatively expensive tools to make up the wiring. So, for many of you it will be
easier to simply solder the wires into the correct holes on the TM3030 PCB.
The type of wire is often asked about on the forum. I use multistrand hook up wire and this
often comes in hobbyist packs of varying colours. The size that I use is typically described as
7/0.2mm which is seven strands of 0.2mm diameter wire. Don't use single strand wire since
this tends to break easily. Remember to keep all wires as short as you can, but allow for a little
extra so that no wire will ever become taut. I usually tin the bare wire ends with a bit of solder
before I place the wire into the board or terminal hole. This stops the wire end from fraying
and makes a better solder joint.
NOTE: Pin 1 of the headers are denoted by a square solder pad on the PCB. All the others are
round.
You have just four sockets to wire up and it doesn't take long at all. Lets deal with the power
inlet first. You'll probably want to include a power switch, but this isn't shown on any of the
schematics. If you have chosen a nice SPST switch, it will only have two terminals. Simply
wire this in series with one of the connecting wires from the power inlet to the PCB.
If you are using a metal case then the power inlet socket should not have a metal mounting
bush. That means that it should not have any metal part on main body of the socket touching
the TM3030's metal case. We do not want any direct connection from the power supply's
wiring to connect to the case.
The power inlet socket has two or three terminals. The ones you need are the terminals that
connect to the the inserted power plug. The third terminal is the 'normally closed' lug,
sometimes called the NC or normalising lug. This should be ignored in our application. The
header labelled AC_POWER will connect to the power inlet and the power switch.
Pin 1 of AC_POWER should go to any terminal on the switch. Pin 2 should go to any of the
two terminals on the power socket that are not the NC lug. You should connect the other
terminal on the switch to the remaining terminal on the power inlet that isn't the NC lug.
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