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Modification – Mackie HM-4

Purchased this 4-way headphone amplifier in May-2019.

It will be mounted in the back corner of my ‘Soundboard’ – getting the required 12 volts DC from the PowerSonic battery.

However – this unit doesn’t have a power switch…!

Mackie HM-4 has no switch.

So I opened up the case, unsoldered the rear DC power plug from the circuit board. The back pin was then bent upwards. I had another spare toggle switch, so one wire got soldered to the bent pin, the other wire was soldered into the hole left on the PCB.

Mackie HM-4 with switch.

A hole was then drilled into case to hold the switch. Power is OFF.

Mackie HM-4 with switch.

Power is ON.

Mackie HM-4 with switch.

Project is done…


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