Knocker kit installation

Note - For Stern SAM-based machines only!

FUSES.. Both the pin 8 and pin 9 taps on the power tap are running through factory fuses. Additional fuses are not required. Pin 8 from factory has a 4A fuse in it, so you may want to replace that with a 3A SB to match pin 9, which runs other coils in your machine. Or just use pin 9.

The cabling is long enough so that you can mount the knocker assembly in the cabinet if you wish. All the taps are in the back box, so if you want to keep it all neat and in the head you can. The 50V step-up board will simply be screwed into the cabinet or back box wall somewhere near your knocker assembly.

Taps are all keyed to match factory. 

What you need..

1. redshiftLED knocker hook up kit

2. Knocker assembly including coil with NO DIODE.

Components of hook up kit..

1. J10 50V power tap.

2. J7 Q24/20V tap.

3. Stern 50V step up PCB.

4. Cable harness.


1. Decide if you want your knocker mounted in the cabinet or the back box.

Entirely up to you. Cable harness will reach either. All the taps are in the back box so if you mount the knocker there everything will be contained in the back box and you won't have to worry about running cables.

2. SNIP THE KNOCKER COIL DIODE (if it has one). Mount the knocker.

Depending on where your soldering iron is, you may want to solder the cable harness to your knocker coil lugs before doing anything else. Up to you as to how to approach the order of the install.

Screw it in place, ensuring the plunger will hit the strike plate.

3. Mount the 50V step up PCB somewhere in the vicinity of the knocker assembly.

Only requirement is that the harness will reach between the step up PCB and your knocker coil.

4. Insert the power tap into J10.

  1. Remove factory J10 connector,
  2. Insert power tap into J10 header,
  3. Insert factory J10 connector into power tap header.

5. Insert the Q24 tap into J7.

  1. Remove factory J7 connector,
  2. Insert Q24 tap into J7 header,
  3. Insert factory J7 connector into Q24 tap header.

6. Plug in the harness.

  1. Plug this end into power tap,
  2. Plug this into step up board,
  3. Plug this line into Q24 tap,
  4. Connect this end to knocker coil.

Solder the coil wires to your coil lugs.

Pinball machine settings for using a knocker.

In your machine menus there is an option for setting the use of Q24.

Set this to "KNOCKER".

Also in the menus, set your knocker volume to zero.

To test the knocker, use the dedicated knocker test in the top operator menu, NOT the Q24 test in the sub menus. Ensure your 50V is engaged (remember opening your coin door disengages the high voltage). The test will fire the synthetic audio knocker even if you have the volume set to zero, but at least the real knocker will fire as well.