The Power Supply to the Power Supply
The inlet, switch and LED wiring on a 19” panel assembly. The top connector is the power supply inlet
coming from a PA-20. The middle bunch of wires is for the two pole DPST rocker switch. At the bottom is
a red 5mm LED in a low profile clip connected to the board via my usual Molex KK method.
The standard method of powering the unit is from a low voltage tapped AC source. The safest
available option is to use a ready made 'wallwart' or ‘line lump’ supply.
You can use any 15V or 18V AC output wallwart of linelump you can source. The current
capability of the mains adapter, sometimes incorrectly called the 'ampage' will determine the
maximum current draw of your PSU.
For use with this board I recommend the Yamaha PA-20 and PA-30 supplies.
Yamaha PA-20
This is a linelump supply and features a fixed 17.5-0-17.5 volt AC output at 0.94A maximum.
This means it gives us two AC outputs with a centre tap or mid point reference voltage. So
unlike the single phase AC adapter output with two leads, this one has three. This means you
need to use the Oakley PSU in full wave rectification mode.
The PA-20 is made for Yamaha products and they are available from Yamaha spares
departments as well as many music shops, eg. Thomann. These are CE approved and connect
to the mains via your local mains connector. They will be different types depending on the
country you need them for. It comes with a handy three way plug at the low voltage end that
you can use with an appropriate socket. If you wish you can ditch their connector and use
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