I had an old, dead Sing Along revived to the point where it was playing well and scoring accurately, but the 100's score reel was a little sluggish, so I disassembled it several times, and adjusted it's switches, without any improvement. After the last attempt, the machine is dead. No lights, not even the beginning of the start up sequence. The hold relay isn't pulling in, the score motor isn't turning, and so on.

I've compared the switch states in the "0", "1", and "9" positions to the adjacent score reels, and they look to me to be correct. So I'm not sure how I could have killed the machine via score reel switch adjustments, but that's all I can imagine. The pictures below show the switch states in the 0, 1, and 9 positions respectively. Can anybody confirm these are correct?

Any suggestions for other potential causes of what now appears to be a totally dead machine? I'm having a hard time believing it's related to switch adjustments on any of the relays, either on the bottom panel or in the backbox, as I haven't touched those. Maybe I'm just missing something that should be obvious?

Thanks in advance for your feedback!

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Crap - because of the way pinside orders attachments, the pictures shown are in the following order: top pic is in 9 position, middle is in 1, bottom in 0. Sorry for the confusion.

Yep, good suggestions. I had already checked the following: checked the (3) fuses near the coin door, and both fuses on the bottom panel. There are credits on the game, and the credit unit switches had been closed to set on freeplay. Cleaned and checked the coin door connector. Checked the start button switch for continuity. Checked the coin door slam switch: it had been bypassed and the switch wires soldered together. Checked the plumb bob tilt and "rolling ball" tilt switches. Checked for any loose wires, both in the backbox and on the bottom panel relays and reset bank.

Thanks Mark! Assuming the problem was caused by something I did by accident, I haven't focused on the reset bank or SB relay because I literally haven't touched it. But I've just about gotten to the point where I can't think of anything else. And although I probably should have known, I didn't realize the SB relay actually had to activate in order to get power to the transformer. I'll check it out and post what I find.

Well, I've lifted the bottom panel and checked all the reset bank switches, and all the other relay switches. They all seem to be adjusted ok - when I depress the relays every switch changes it's state from open to closed or closed to open. I even tested outlet voltage (123V+) and input voltage at the transformer and at the "far" side of the fuse holder next to the transformer, also at 123V.

I know I'm missing something, and I bet it's something simple. So back to my theory that the problem relates to my repeated score reel adjustments. Can any of the score reel switches, if mis-adjusted, actually prevent a machine from even beginning the start up sequence? This machine is currently dead - and I mean dead - no lights, no relays clicking, no score motor turning, nothing.

Likewise, can a mis-adjusted tilt or slam switch actually prevent any sort of start up sequence beginning?

Ok, maybe some progress now! Now when I manually activate the hold relay, the machine powers up, the score motor runs and continually steps down the credit unit (and keeps going, I assume because the credit unit switches are bent for "free play"). The score reels do not reset.

(And yes, I pulled and checked all the fuses with a DMM).

What next?

Wow, success at last, I think. The machine now powers up, resets the score reels to zero, decrements the credit unit, and loads the ball into the trough. Game play is normal including ball count and game over. So keep your fingers crossed.

For the benefit of those that offered suggestions, and anybody else facing a similar problem, here are the other steps I went thru to ultimately fix the problem:

1. I removed the playfield hoping to help isolate the problem, but also so that I could pull out the bottom panel. For me, trying to inspect and adjust reset bank switches is about impossible without pulling the bottom panel out. I just rested it across the side rails.
2. The only switches I cleaned were on the SB start relay. I did not attempt to mess around with the large switch "under" the SB relay.
3. At "jrpinball's" suggestion, manually activating the R hold relay actually got the machine to begin the start up sequence, although the score reels weren't resetting.
4. On the schematic, relay DS controls the score reel run outs. That relay is mounted under the playfield. So I went ahead and reinstalled the playfield. Then the score reels reset properly to zero, but the ball wasn't being loaded from the outhole to the ball trough.
5. On the schematic it looked like relay O controls the outhole ball kicker. It should have 5 normally open switches. They looked good but I did adjust one switch slightly. The machine still would not load a ball.
6. From the schematic it looks like score motor switches 1C and 4C can affect relay O, so I checked and cleaned those switches. Still no ball loaded.
7. I thought maybe a tilt switch being closed would prevent a ball from being loaded, but maybe not prevent the rest of the start up sequence. So looking at the schematic, all four tilt switches are shown as having or-wh-red wires. Checking the tilt switch in the backbox (it has the correct wire color), it was bent closed. I probably did this myself while trying to track down the problem. Sure enough, opening that switch allowed the game to finish the start up sequence, including loading a ball to the trough.
8. So oddly enough, the problem was not related to the adjustments I made to the score reel switches; I haven't touched them since the machine "went dead". My best guess is that the SB relay had a dirty or slightly mis-adjusted switch. I compounded the problem when I closed the tilt switch in the backbox, although it only prevented the ball from being loaded, not the start up sequence from beginning.

Man, that's a lot of crap to go thru for a game that was working great yesterday. I hope this gives the group some feedback on all the excellent suggestions, and that it might help somebody else that has a similar issue with the same generation Gottliebs. Thanks for all the help!!