Old Chicago
Bally, 1976One image has been uploaded to this topic. (View topic image gallery).
I picked up an Old Chicago a couple of years ago. I immediately put it in storage and then brought it out for a playfield and cabinet restoration process about a year ago. I just tried starting it up for the first time. When I flip the power switch the lock relay energizes, score motor runs continuously, the drop target bank resets continuously and the saucer kicker fires continuously.
I don't have a copy of the schematics. I'm trying to use a pdf version. Any suggestions?
Check p.3 of the manual for start sequence: https://www.ipdb.org/files/1704/Bally_1976_Old_Chicago_Manual_no_schematics.pdf
Schematic and other info available here: https://www.ipdb.org/machine.cgi?id=1704
Thanks, reading those and checking a number of potential items was the first thing I did before posting here. Looking for some more specific advice....
Are either the Bonus Hole Score relay or the Outhole relay stuck on too? Those two would explain most of what you're seeing. If they're not stuck on, do their switches open and close as expected? Any bent tabs, etc. that might close their switches?
/Mark
Quoted from MarkG:
Are either the Bonus Hole Score relay or the Outhole relay stuck on too? Those two would explain most of what you're seeing. If they're not stuck on, do their switches open and close as expected? Any bent tabs, etc. that might close their switches?
/Mark
Neither of those are stuck. They appear to open and close normally but tomorrow I plan to pull the bottom board out and look at everything carefully (again). Past experience tells me that just one subtle, slightly out of adjustment switch can foil an EM.
Quoted from pinheadpierre:
score motor runs continuously
Which one of these 13 switches is keeping it running?
Pinball (resized).pngQuoted from HowardR:
Which one of these 13 switches is keeping it running?[quoted image]
Thank you - I'll report back!
Which one of these 13 switches is keeping it running?[quoted image]
Getting closer. I went through all 13 switches checking for shorts and proper adjustment. A couple seemed slightly off so I cleaned, polished and adjusted the suspect ones. Now the game powers up, the start button resets the game, serves a ball and then promptly steps through all 5 balls and ends the game.
I checked the outhole switch with my multimeter and found that it was shorted closed somewhere in the circuit. Detaching the largest of the three jones plugs from the bottom board breaks the short, so I'm concluding that there is a short somewhere in the bottom board. Does this sound right?
I am thinking this could be traced with a jumper wire but am struggling to visualize where to attach the first probe from my multimeter. Any thoughts/suggestions?
Now the game powers up, the start button resets the game, serves a ball and then promptly steps through all 5 balls and ends the game.
Are either the Bonus Hole Score relay or the Outhole relay stuck on too? Those two would explain most of what you're seeing. If they're not stuck on, do their switches open and close as expected? Any bent tabs, etc. that might close their switches?
/Mark
Question: should each wire from a playfield switch terminate at a male jones plug location with the same color wire? The red/black outhole switch wire reads continuity to a green/yellow wire on the large male jones plug.
Question: should each wire from a playfield switch terminate at a male jones plug location with the same color wire? The red/black outhole switch wire reads continuity to a green/yellow wire on the large male jones plug.
....both of which appear together on the bonus unit under the playfield. Just chronicling my exploration/ thought process out loud here. Gotta put this aside for the afternoon to attend to the rest of my life. 
Question: should each wire from a playfield switch terminate at a male jones plug location with the same color wire? The red/black outhole switch wire reads continuity to a green/yellow wire on the large male jones plug.
Unlikely. There are often relays, steppers or other control logic under the playfield (e.g. the pop bumper relays) that playfield switches connect to instead of jones plugs. This was probably done to minimize wiring and reduce the number of wires going through the jones plugs.
Read up on continuity in this forum. Continuity doesn't necessarily indicate a direct connection. If you're measuring an ohm or less you probably have a direct connection between the two meter probes. Any more resistance and you may be seeing another path through a coil or something. The beep on your meter won't distinguish between the two. You need to double check the resistance value.
The different wire color indicates that the two wires aren't the same circuit. Wire colors on the same circuit usually only change when using short jumpers to connect a few points that are physically close together. In that case you might see one color leading in (e.g. red-white) and another color (usually a solid color) on a short piece of wire connecting nearby things together like an EOS switch to a flipper coil.
Unlikely. There are often relays, steppers or other control logic under the playfield (e.g. the pop bumper relays) that playfield switches connect to instead of jones plugs. This was probably done to minimize wiring and reduce the number of wires going through the jones plugs.
Read up on continuity in this forum. Continuity doesn't necessarily indicate a direct connection. If you're measuring an ohm or less you probably have a direct connection between the two meter probes. Any more resistance and you may be seeing another path through a coil or something. The beep on your meter won't distinguish between the two. You need to double check the resistance value.
The different wire color indicates that the two wires aren't the same circuit. Wire colors on the same circuit usually only change when using short jumpers to connect a few points that are physically close together. In that case you might see one color leading in (e.g. red-white) and another color (usually a solid color) on a short piece of wire connecting nearby things together like an EOS switch to a flipper coil.
Interesting. Just when I think I'm getting the hang of EM diagnostics, something fresh rears its head and teaches me otherwise. I appreciate the help. I do feel that I am slowly getting better at this. The thing about EMs is that once you get them cleaned up and dialed in they seem to go a really long time without trouble. In the meantime, while happily playing my games, my repair/diagnostic skill growth comes to a standstill.
With the help of folks here I have managed to get over the hump on this one. I've got it to the point where a game starts and stays on ball one. There is still some adjusting of various stitches to do to make it work correctly. I'll be taking a break from this for a couple of weeks. Hopefully when I return to it, my sailing is a little smoother.
Thanks everyone for your help. 
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Springfield, MA