Adjust the 9 position contacts out a little. They are probably putting a little to much force not causing it to advance.

Likely your 9th pos. sw. on the reel. Read more here: http://www.pinrepair.com/em/index2.htm#reels

Don't oil; the vast majority of the machine does not need it.

+1 on not using oil. EMs don’t need oil anywhere, it just attracts dirt and causes problems.

If one player score causes others to score (or tries to), look at re-gapping the reset relays

also tighten the switch stacks before re-gapping

Looks like it may be somewhere on reset relay #2

https://www.ipdb.org/files/1704/Bally_1976_Old_Chicago_Schematic_Diagram_paginated.pdf

Check this for the lites:

Capture (resized).PNG

IPDB for the schematic: https://www.ipdb.org/machine.cgi?id=1704

Circles indicate lites. Not certain about the arrows; not sure I've seen those before.

So yes, check that make/break sw.

The circles you drew indicate wire colors and number of uses. There's a legend on the schematic labelled "WIRE COLOR CODE" that tells the specifics.
The arrow you drew points to a wire.

Ha! I skipped right over the hand-drawn stuff ...

Hi Gorgar666
Danger - Your pin has 110VAC Line Current, operates Relays and Steppers with 48VAC, Lamps with 6VAC - current can kill people. Always toggle-off and unplug the main power cord when You work on the pin. ONLY plug-in, toggle-on, start a game when You NEED current for testing. Ask a friend to help - locate the 00-90 Unit - also called Match Unit - most likely it is in the Backbox - Your friend plays a game, You watch this Unit - everytime Your friend makes 10 Points: The Unit must step one step. Look at the axis of the Unit - some kind of a gear is mounted - in one position of the unit the gear opens a mounted switch - in next position of the unit the gear allows the switch to be closed. Through this switch current may flow to the Coil of the Alternator-Relay - locate the Alternator-Relay - a simple relay --- non pulling, the friend makes 10 points, the Match Unit steps one step and the Alternator-Relay is pulling --- the friend makes another 10 points, the Match Unit steps one step and the Alternator-Relay is not pulling and so on.
IF (if, if) the Alternator-Relay does never pull: Be careful - wear rubber gloves or use an wooden stick - PRESS on the armature of the Alternator-Relay - 1,2,3 .. seconds - up to a minute --- does the friend now see lites, makes 10 or 100 points - means manually operating the Alternator-Relay makes the pin to function ? Write about.

We live in different time zones - I am ahead of You, maybe 7,8,9 hours - it is time for me to go to sleep. Greetings Rolf
P.S.: Good stuff: http://www.planetarypinball.com/mm5/merchant.mvc?Screen=BOOK --- click on Bally 1976 Parts Catalog then scroll through the pages --- from here http://www.planetarypinball.com/reference/partsmanuals/BLY_Parts_1976/index.html#/96/ I copied the drawing.

0Old-Chicago-Work-21 (resized).jpg

Rolf - I noticed this post and am having a similar problem with my Old Chicago. Alternator relay was working fine and then, all of a sudden, I noticed the the top rollover lanes and top thumper bumpers weren't alternating each time a 10-point switch closed. I did what you said, watched the 00-90 unit as someone else closed a 10 point switch. The 00-90 unit rotated flawlessly.

Then I opened up the game and did the same thing, watching the alternator relay. It wouldn't close - stayed stuck open. I put on a rubber glove and manually closed the relay with a piece of cardboard and the thumper bumpers and rollover lane lights alternated.

So the 00-90 unit works and the alternator relay does what it's supposed to do. It just won't energize. Any guess why?

FYI - i cleaned the switches in the relay and they all seem to be gapped properly.

Thanks!

Here's a photo of my alternator relay (it's the one in the center).

Old Chicago Alternator Relay (resized).jpg

What is that relay to the right? looks like what I think is the spring retainer is loose. perhaps the spring is missing as well.

Relay to the right of the alternator is labelled "Top Hole," which I believe would be the top kickout hole.

You are correct - the spring is missing, although that relay is functioning properly and kicking out the ball.

That wouldn't affect the alternator relay, would it?

I guess not according to the schematics ... what is the resistance of the alternator coil ? should be 78 Ohms , (can check with machine off) if infinite resistance see if tiny coil wire came off lug. I would guess a zero resistance would blow a fuse.

Just checked resistance of alternator coil as you directed. It shows 72 Ohms. Close enough?

If you suspect the Alternator unit coil, swap it for another G-32-2500, on the Ball Index or Tilt relay.

That value seem good.

There is a Jones plug between the match unit & the alternator relay. the schematic shows the wire color as "98-7" the color chart is on the bottom of the schematic and there is a map to where "98-7" lands on the jones plugs in the back box ("cabinet to insert plugs")

https://www.ipdb.org/files/1704/Bally_1976_Old_Chicago_Schematic_Diagram_paginated.pdf

Gotcha - I found the Jones plug and the wire from/to the alternator. It's plugged in, but I'm guessing it's not making the connection properly...?

What's the best way to clean the plug (I'm still a newbie)?

Find out if it's the Jones plug connection before cleaning it. Use Alligator clip jumper wires
http://www.planetimming.com/Pinball/troubleshooting/EM%20Troubleshooting.pdf
http://www.pinrepair.com/em/index3.htm#features

Thanks to both HowardR and chas10e! I jumpered the connection as you suggested and it worked - alternator now working as it should. When I removed the jumper wires, I tried it again and it's still working. I'm guessing that by reseating the Jones plug a couple of times, it "cleaned" the connection.

I'm curious: is this a common problem? Jones plug connections losing the connection for no reason (other than the fact the game is 43 years old)?

One postscript I wanted to add to this (for anyone who comes along later with the same problem):

I suspect the Jones Plug wasn't the problem after all, although I would not have found it without HowardR's suggestion to use alligator clip jumper wires (and chas10e's original help). When I attached the alligator clip to the alternator relay switch (to the grey/black wire on the right) I noticed that the screws holding the switch were very loose. Perhaps from the constant vibration that unit takes? So I tightened both of those screws, then connected the alligator clip to the switch, connected the other end to the alternator relay and viola, it worked. And then, when I disconnected the jumper wires, it still worked.

I initially attributed that to the jones plug connection being "cleaned" by reseating it a couple of times. But now I'm thinking it was the screws being loose on that switch which prevented that switch from closing. That seems a better explanation for why it was working one day, and then not working the next. (Better than the jones plug suddenly "loosing connection" for no apparent reason.

Anyway, that for all the help. And hope this helps someone else down the road...

Old Chicago 00-90 Unit (resized).jpg

Two corrections: The screws were loose on the 00-90 cam switch (pictured above), not the alternator relay. I noticed it when I attached the alligator clip to the grey/black wire (aka 98-7).

And I meant to say "Thanks for all the help!"