On my Bally “Monte Carlo”, the lock RE. really does nothing more that turn on the GI lights and release the Game over RE. But can be de-energized when the delay RE is energized. Which was not straight forward on the schematic.
On your Schematic, looks like both the game over trip coil and the Lock RE. energize, this will de-latch the Game Over RE. then the Lock RE will de-energize the Game over Trip coil, Needs to be de-energized, because latching of the Game Over RE is mechanical. (Looks the same on my Bally)

It’s a start.

I’m sure this is true.

Thinking more about it, it’s all just a case of timing. If the gap on the switch of the lock relay is wrong then you could have a problem. If you tried to use the G.O. RE. to control the release coil, the switch timing would be critical, maybe why it is the way it is. Bally and Williams both use this method on many machines, must be the best and/or cheapest solution.

Steve, during another post I realised the purpose of the lock relay on your machine (And others). It insures that the machine is at a known position at power on, “Game Over”. If you turn the power off in the middle of a game then back on, you will be at game over.

Hey SteveFury.

I do not know the technical end of the why or why not of the circuit, but I can tell you what Steve Young told me over the phone about that relay on my 1976 Williams Space Odyssey when I asked him how to limit the hum on the "Lock Relay" when it is on.

He basically told me the circuit was useless, was not needed and to simply by pass the coil altogether.

When I told him others have said to me that the machine might not know when the game is over if I did that he told me that would not be the case......and we know Steve is always right or at least he does.

What did I do?

Because I want a machine to be as original as possible I replaced the coil as you did as it was shot too and left the relay as-is and just sanded the actuator plate a bit to smooth it out to reduce the hum which worked somewhat.

So is the circuit completely useless? Well, Williams did not think so and built the machine but Steve Young says yes.

I never experimented to see if what Steve Young said was true for the reason stated above but you are more than welcome to and let us all know if so inclined, but I know I'm not going to waste my time as I am happy with my machine as-is.

Ken

Thanks for explaining this Steve as Steve Young did not bother going into the details of this like you.

I actually have a Space Odyssey 2 Player, but wanted this machine because of how much fun I had at the arcades back in the 70's with Space Mission. This was my first machine to launch me in the hobby over a year ago. More artwork to see on "SO" and less to fix was my reasons for wanting this title compared to "SM".

As far as a comparison to "SO76" they are completely different feels and style for playing. My wife loves "SO" and I as well so it is a keeper. "SO" is a great feeling when you can nail the flag at 1000 points which is hard and getting the horseshoe for that advance bonus. She likes "SO76" but I really like it as that center Kickout hole makes me want to be a better player so I can score what I want, when I want, but denies me that quite a lot, so I try again, etc and is also a keeper.

You can check my profile for other machines I have if you like. 3 are currently working, all 100%, "SO, SO76", and 4 Square. All the others are major projects with a 1973 Williams Gulfstream being currently restored and will be finished sometime late fall or early Winter. I am a big Williams fan for fun and dependability, but rate Gottlieb as having the best overall games in general.

Just picked this one up at a local auction, Stardust was one I was thinking of doing a quick fix and selling but after Chris Hibbler said how fun it is and that he wanted one I may just have to do a major restore on it and see if I want to keep it. I love the colors and like the layout of the Playfield is in good condition. Great Backglass art although mine is shot condition wise (3). Cabinet wood/paint in good condition, coin door is shot.

A lot of the machines I pick up are 1 step away from the dumpster, so I save them. They gave me a lot of fun as a kid so I want to give back and keep them from the parts bin.

I love fixing these things more than playing them, but only by a little.

Ken

No. Have not even plugged it in.

I did a "full on 10 minute" eye inspection though

It only had one broken switch left in the coin box so tracked that down right away to a broken pop bumper switch that blew the 24v Playfield fuse. 2 coils are fried as well, but the rest inside looks great/complete including the steppers.

I think this machine was stored for a long time after it broke (1982?) in a place it should not have been as the outside stainless steel everything took a big rust hit and the Backglass.

Looking forward to working on it but most likely not till Summer 2013 or later, too many other projects a head of it.

Ken

I remember back in the day ('70's) being first to play some of those machines, right after the arcade opened, right after the guy turned them on, and getting a free game every now and then. I was too stoked to wonder why.

I feel the same, but I haven't tackled an EM yet.

Thanks for this thread Steve. I'm currently working on my first EM as a repair for someone. A Williams Aztec. Today, I reinstalled the relay/motor board after cleaning and fired it up minus the playfield to test operation. The first thing I noticed after turning it on was the coil hum of the lock relay. I was, too, baffled by why this was on. The coil is in decent shape but it showed more wear than any of the others. It became, of course, very warm. I took notice of this to look up later and was happy I found this thread. Now I see it's normal. Thanks again. FYI, manually scoring the machine worked without issue. Now, on to the playfield.

This might be the same on older Williams games too. I have a Ding Dong, made in 1968, that has the lock relay permanently closed. That means when I hit the switch, the game lights up without hitting the left flipper button. And if I turn it off in the middle of a game, then turn it back on, I'm still in the middle of the game.

It was this way when I bought it and I've never fixed it. I assume the coil got cooked because it's one of those high resistance continuous duty coils, but even so they eventually get pretty weak. It probably couldn't hold the relay closed any longer so they just forced it closed and went on their way.

The game will tilt and it will go to game over normally. But it won't do what I posted above.

^^^

yup, true of the older games as well... i removed the relay entirely from my never ending project, and that is the behaviour that i am expecting...

Purpose of the lock relay is to prevent it to be abused.
If the lock relay wasn't there and de game has tilted you could turn it off and on again, even getting the same ball back in play because of the index relay falling off.
So you could "cheat" a game.
Or when the bounce switch was triggered by a frustrated player it would be literaly "game over"