If your Knob is dead, don’t bin it, fix it.
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.
- Here in the UK the replacement power supply transformer and fuse can be purchased from RS Components.
- Transformer part number is: 2239351 (cost £14.69)
- Fuse part number is: 537-1262 (cost £1.95)
- For the rest of the world, copy the parts specification from RS Components website then search for them in your local electronics parts supplier.
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.
- 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.