HOW TO FIX A DEAD MACKIE BIG KNOB POWER SUPPLY

By Troy

If your Knob is dead, don’t bin it, fix it.

My Big knob died, it lay dead and would not light up, no power. No biggie’ I took it apart only to found out the fuse was blown/burnt, I bridged the fuse, which still got burned after powering up. I round it down to the power supply transformer. Judging from the circuit boards, it seems Mackie cut some corners with the power supply. The symptoms before mine died were, humming sound in headphones, slight vibrating noise coming from the knob, then died, no lights, nothing, no life.
This isn’t a full in-depth tutorial. It’s more like a Brain Spraker to spark the DIY element in yourself to let you know you can repair your Big Knob without the need to pay Mackie £300 to repair it for you.
All is needed to repair the Knob is, a multimeter, soldering iron, soldering wire, soldering wick or soldering suction tool to remove the faulty power supply from the circuit board, some screw drivers, the replacement parts and some gentle time.

The power supply board looks cheaply made, with a green clad board. It looks very different from the rest of the other circuit board which is blue. The dead transformer was made in China. The replacement power supply from RS Components was made in India.

The Steps

  • Remove the screws from the Knob/take it apart. It’s very straightforward.
  • Unplug the power supply’s output cable (the cable which has three white wires and one black wire).
  • Unscrew the power supply circuit board from the Knob’s housing. Remove the dead tranny then pop the new one in.
  • When all is well and you’re satisfied the new power supply is installed correctly.
  • With the power supply board not connected yet to the main board.
  • Power up the Knob by plugging the kettle lead to the Knob then to your power outlet, check the power supply circuit board’s output connector with your multimeter.
  • Set your multimeter to DC volts.
  • Place your multimeter’s Black probe on connector DGND, Red probe on connector +15.5V. If your multimeter reads a voltage between 15volts and 17volts all is fine. do the same for the other two connectors, AGND and -15.5v.
  • Also to correctly diagnose if it’s your power supply is at fault, you can check this location with your multimeter.
  • See attached photos for visual illustration.
  • If all goes well as it should, screw the Knob back together.
Many slutz do not like the knob, I don’t know why. Maybe it’s because the Knob is too big. Many Platinum records out there were referenced through a Big Knob. Goes to show the Knob is a very great tool if used correctly.
I hope this will help someone that has a faulty Mackie Big Knob.
If your Knob is dead don’t bin it fix it.

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1 comment

Nico 10/08/2018 - 6:32 am

i just fix my big knob with your help 🙂 thanks buddy !

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