Could be several different things from a simply menu setting to a coil, diode, solenoid, relay or transistor. Start by combing through all your menu screens looking for a knocker section with on/off/hi/low options and adjust accordingly. If that doesn't work, find where the knocker mechanism is and look for loose wires a burnt out coil or broken diode on the coil.

Others far more technical than I will answer too and help you out if it's more than what I've mentioned. No worries, you'll get it resolved. GL and welcome to the Pinsanity!!!

Edit: If you go to the main forums screen, you'll see the "Forums Search Feature" Up in the top right corner. Click it and type in, "Knocker". A lot of different threads will pop up with knocker problems and resolutions for you. Those may also be of help to you. The owners manual may also be a great help with resolving the issue as well.

There are some switches on the front door than need to be closed in order for the knocker to work. They're with the coin switches.

Don't believe OXO has diodes or transistors.

You should be able to activate the knocker via the replay step up. I'm not sure exactly what that looks like on this machine, but it's entirely possible that it's simply disconnected.

Check all contacts within the circuit starting with the anti-cheat [slam switch ] and ending with the Eos on the credit unit.

1 Oxo1.JPG

2 Oxo2.JPG

Yours should be like this shown below, the switch circled activates mine when i press those contacts together.

3 Williams credit unit reference (500x452).jpg

4 Williams DMS (450x405).jpg

Mr pinball 2nds the notion:
From> http://user.xmission.com/~daina/tips/pub/tip0196.html
If your Williams electromechanical replay knocker is not firing it is most likely due to the switches on the coin door. The knocker circuit is run through the coin switch on the coin door. Check that the normally closed switch on a make-break coin switch is closed. These often are all bent out of shape by someone trying to put credits on manually.

I have a '74 Williams. Knocker is likely in the same spot as mine. Right side... very close to front.

knocker.jpg

Reading the manual, make sure the game adjustment Jacks are set to Replay and not Extra Ball feature and also check to see that the Number Match adjustment jack is in On and not Off position.

Since this has been set up for free play, I would check the SWs at the credit reel. The best way to set a EM to free play is to keep the Credit reel zero SW closed. at that location there is also a credit reel EOS SW. if this SW is not closed then the knocker will not fire.

The knocker still fires on Williams games that are set to extra ball instead of replay. It will still fire even if the match feature is turned off, to signal extra balls being won.

The post above is trying to say there is a switch that is closed when the credit unit steps up to award a game. The switch is normally open but is closed when the wheel steps up.

Given that the OP isn't even sure where the knocker is on the game, we probably shouldn't get too far ahead of ourselves on this one.

After looking at the OXO schematic i see the extra ball circuit , but no pass through the knocker assembly.

_{Post edited by Pin-it: Knocks on replay}

There are a few on flea bay right now. Luckily, there are many, many Williams EMs that most people wouldn't walk across the street to piss on if they were on fire, so there tends to be a lot of parts available.

OXO is not in this category. A lot of people like it.

Not a bad thing at all. It leaves some pretty decent games for those of us who like the games at very reasonable prices.

PBR can sell you a Gottlieb knocker assembly that will work fine in a Williams game. Just make sure they know what game you're going to put it in so they know the correct voltage and can change out the coil accordingly. It's around $30 bucks plus shipping.

I put one in my Williams Ding Dong which had the knocker missing when I got it. That is without a doubt the loudest knocker I've ever heard in my life. Thing shakes the walls when it goes off.

If you don't want that, they're around on fleabay. Just be aware of what you can buy one new for and bid accordingly.

This isn't true.

The knocker is activated by the credit unit stepping up one, NOT by any other relay (certainly not the shoot again relay).

Knockers on Williams EMs only fire when a match, special, or replay score is hit, not for EBs.

OK, I don't know what I was hearing then when I owned a Williams Triple Action. The game was adjustable four different ways, but you could adjust it to straight add a ball if you wanted. When you got an extra ball, the knocker fired. And they don't have shoot again relays, because you're able to win more than one extra ball on a single ball. Shoot again relays exist on games that only allow you to to just repeat the ball you're on.

You're out to lunch on this one, Levi.

I'll rephrase - Williams MULTIPLAYERS (like OXO - the game that is the subject of this thread) the knocker will ONLY fire if the credit unit is stepped up - a la match, replay, or special. That is, if you switch the replay adjustment to extra ball (instead of credit), also turn off match, you will never hear a knock (except maybe when you put quarters in the game to add credits).

On a williams one-player add a ball game like Triple Action, the knocker will indeed fire if you get an added ball (NOT a shoot again, like OXO).

To sum it up - on OXO - or any other williams multiplayer - you will never hear a knocker if match is not on, and/or replay is not set to credit.

Hope that clears it up.

ebay.com link: Williams EM Dealers Choice Pinball Machine Knocker

Plug and play, baby!! $32.25 shipped. Note, it even has the jones plug.

I can agree with that. I've never owned a Williams multiplayer so I don't know how that works, and I've never played one in the wild that wasn't set on replay. It makes sense, though, you can't rack up multiple extra balls on a multiplayer so the only option is repeating the ball.

Thanks for expanding on it.

_{Post edited by EMsInKC: added info}

Right.

On Triple Action, the knocker isn't just activated by the credit unit, it's also activated by the ball count unit when it counts up. That unit steps up, and also steps down.

On OXO, it only steps down (or does a quick full reset), and doesn't activate the knocker

Honestly, the Williams knockers are crap. Even a well functioning one makes a dull thud, not a spectacular crack.

If PBR will indeed re-fit a knocker unit with a Williams coil for about the same price, you should go that way instead of the ebay version. And hacking it in to the jones plug is easy. Gottlieb knockers are WAY superior. They were still using that crappy knocker on early Williams stuff like Firepower.

I have a Triple Strike that is also convertible but it acts more like a multiplayer. It can only count up to five balls. When you score the "extra ball" on it, it just holds you on the ball you're on. I should have thought of that.

I would concur that the Gottlieb knockers are superior. None of my Williams games has a knocker that sounds like the one I got from PBR and installed on the Ding Dong. None of the factory Gottliebs sound like it either. Damned thing sounds like a .45 auto going off. It's located in the back of the cab, not the front, and it's just incredibly loud and strong. I've never heard a knocker on any other game, anywhere, in nearly 50 years of playing EMs, that sounds like this thing does. Ding Dong is a 25v game like the Gottliebs of the period, this was after Williams changed from 50v games, so it just installed straight into the game. But PBR will change out the coil in it to account for it being installed in a 50v game. It will still be a Gottlieb coil, but it will work just fine.

No knocker will do it, lol.
Guys read the OP post above.