Perhaps there is a dedicated setting that needs to be changed in the adjustments?

I know this is an old thread but I figured I'd reply in case you didn't figure it out. In the newer versions of that board 520-5254-00 Pin 2 is 20v, you must connect that pin to a 20v power source in your game in order for the board to work. The later revisions of the board included this because some games would have the knocker go off on initial power up because the 50v power supply comes on immediately and any errant signal from the boards during boot up would cause a "knock". The 20v side of the power supply isn't brought online until the game boots so this was a simple solution to the problem.

Long story made short, connect pin 2 to 20v and it'll work.

That doesn't make sense. Are you sure the 50v and the 20v are using the same ground you are using for the boards pin 3?

I usually tap the 50v, 20v, and ground from the playfield harness and the Q24 output from where ever it is output (depending on whether it's SAM or Whitestar).

Also, your knocker must have the diode removed.

Was hoping someone could just make a wiring harness to connect the knocker coil to the step up board and wherever in the back box please.

There was a guy making these a while back, but he has stopped, along with his other pin related business.
Hopefully someone else will make them.
I bought a couple and would pick up several more.

Check the voltages at the step-up connector with your multimeter: verify that your power taps are good.

Where are you getting ground? Check your ground continuity to the ground braid to make sure it's good. I just tap the ground braid directly.

You can then verify the circuit is working by unplugging from the Q24 harness connector and briefly touch that P1 signal wire to ground braid. Knocker should go off.

It does sound more "setting" related than anything else. It sounds like Kawydud that you have all of your connections/wiring correct. I have several of these to install myself and am following this with interest.

How are you testing that it's not working in the game? Have you played to a point when it should knock? Have you run the knocker test instead of just the coil diagnostic test?

I just noticed on my ST Premium that my knocker also won't activate in the coil test, but I know it works. There's a separate knocker test in its own menu option, that one works for me.

I'm not sure that I ever found the knocker test in the diagnostics menu. I just tested all my inputs before wiring it up and then playing through the game until the knocker was supposed to sound or getting a match. That's how I tested it and it worked.

If you do find the test make sure you pull the interlock on the coin door so that the high voltage isn't disabled for your test and of course be careful under the playfield with the high voltage on.

The key I found was to make sure you have 20v and 50v, and that the ground reference is the same the power supply references for the 20/50v. Someone above mentioned the ground braid which should also be find since the PS is grounded to it. Just make it all nice and tidy.

I'm sure you'll get this figured out.

Knocker test isn't hard to find: just scroll to the right of sw, coil, flash, lamp options: right before and next to the speaker test.

Knocker kits now available here -https://www.pinballlife.com/real-knocker-kit-for-stern-sam-machines.html

Got mine ordered for my Tron Legacy Pro!