NOTE: TO ANYONE HAVING TROUBLE VIEWING THE UPLOADED SCHEMATIC, HOVER OVER THE THUMBNAIL THEN CLICK THE DOUBLE HEADED ARROW IN THE BOTTOM LEFT CORNER. GIVE IT A FEW SECONDS TO RENDER CORRECTLY. IT MOVES SLOWLY. NOT SURE WHY BUT THIS SEEMS TO BE THE ONLY WAY IT WILL DISPLAY WITHOUT BEING TOO BLURRY TO READ.

Recently picked up a "Pinball by Stern" from 1977. Marked as a Stern but internally, it's a Chicago Coin. I'm having an issue where I turn it on, press credit button, score reels reset (most do, I have to reset 2 of them by hand), but the score motor keeps turning and the reset relays keep hammering away. I have cleaned and rebuilt all score reels. I have verified that every one has continuity on the zero position (even the two I have to reset by hand) as Chicago Coin's don't use an EOS switch. While everything is trying to reset I can manually activate the Reset Relay and everything stops and it kicks a ball out and plays like normal all the way through a game. Well, mostly normal. I do have another issue that I'm not sure is related to the reset issue. I'll list it here just in case. During gameplay the machine will end the game after 4 balls. It skips the 5th ball and goes right to Game Over. It does the same when set to 3 balls. It skips the 3rd ball and goes to Game Over. But if I manually activate the Ball Count Unit it goes through all 5 balls lighting the appropriate lights on the back box as it goes. There are one or two other small issues relating to bonus lights and things like that but I don't believe those are related to my reset issue.

So far I've cleaned and rebuilt all score reels and verified their continuity in zero position. I've cleaned and put light coat of super lube on all stepper units and verified that they all work by manually activating them and watching the appropriate lights change. I've cleaned switches on all of the relays relevant to the reset/start up process (at least those that I've been able to identify with the schematic.) Also cleaned several score motor switches relevant to this process. I would note that one of the related score motor switches produces a large blue spark when activated. This occured before and after cleaning. Not sure if that is indicative of a problem but it's the only motor switch that does this. I believe it was the A1-3 or A1-4 switch. Not sure at the moment and I'm not in front of the machine. Checked all fuses and verified continuity and appropriate amperage ratings.

So, any suggestions as to what I can try next or something I overlooked? I've attached the continuous schematic. I'm relatively new to this. I purchased my first EM a few months ago. I was able to learn the schematics and eventually got that one fixed and working 100%. This one is proving to be a little more difficult though. Lol
PinballEM2a.jpg

Howard, I noticed if you hover over the schematic thumbnail and click the double expanding arrow in the lower left corner it will display properly. No idea why but see if that works for you.

Thanks for the response Mark. Pretty sure I understand what you're suggesting. Basically bypass the score reels to see if one of them is causing the problem. Could you take a look at the schematic and show me where to place the jumpers? Not sure if I should be looking at how to jumper each reel individually one at a time or if the intent is to bypass a whole set (player 1 set, player 2 set, etc.) at once.

Made a little progress last night. As I mentioned in my 1st post some of my score reels weren't resetting and I had to reset them by hand. I figured out that some of them were not receiving the signal to reset. Traced the problem to an out of adjustment switch on the score motor. Because it wasn't making contact it wasn't pulsing the switches on the reset relays in the back box. Cleaned and adjusted that switch and now all of my score reels are resetting to zero upon start up. However, the game still isn't ending the reset cycle. I'm almost certain it has something to do with the score reels. Still going to try bypassing them. It's just a matter of figuring out which wires go where in the reset circuit so I can jumper it correctly. The schematic doesn't tell you some of the wire colors so that's making it more difficult.

One more post on this thread just to sort of wrap things up. I finally figured out which wires go where. I had to pull apart the tied together harnesses so I could trace the colors. As I mentioned, the schematic doesn't tell you all of the colors. Once I figured this out I placed a jumper from the last zero position connection on the player 1 set of score reels to the wire that feeds back to the reset relay. Effectively skipping players 2, 3, and 4. Now the game resets correctly and pops out a ball. So what this tells me is that there is a zero position connection problem somewhere on the score reels of players 2, 3, or 4. Which is exactly what was mentioned earlier in the thread.