Sorry it took so long to post a response for this question. Please provide some additional information to help narrow down where the problem might be.

This is happening on a Gottlieb Big Shot two-player game, is that correct?

Assuming this a Gottlieb Big Shot, is there an entire bank of drop targets that are not resetting at the start of each new ball in play? Is it just the drop target bank on one side, or is it both sides? If it's just the drop targets on one side, which side is failing to reset?

Thanks - TimMe

On each drop target bank, each drop target has two switch stacks that it actuates.

On the back side of the drop target frame, there is a switch that is momentarily closed as the target falls, to give you score for hitting the target. This switch should be open when the target is fully up or fully down.

On the front side of the frame, there is a switch for each target that detects when that specific target is down. We can call these the "target is down" switch. Each of these switches should be open when the target is fully up, and closed when the target is fully down.

If all the targets are up, and you are getting bonus score when the ball drains, the first thing I would do is check the "target is down" switch for each drop target, to see if some of them are out of adjustment and making contact even when the corresponding drop target is up. That would give you fake bonus scoring.

- TimMe

Sounds good. Just to be sure I understand 100%, did you confirm that every target down switch was open when the target is up? They all need to be open when all drop targets are up, otherwise you'll get bonus scoring when you are not supposed to.

When all the drop targets are up, are any of the pool ball lights in the rack on the playfield lit? They should all be out. There is a direct circuit correlation in your game between each lit pool ball and 1000 points of bonus being scored. If any of the pool balls in the rack on the playfield are lit, even when all drop targets are up, it very likely means that the target down switch on the corresponding drop target is somehow making contact. If so, that needs to be fixed.

If everything mentioned above checks out OK, another test you can try is to knock down all the drop targets and then see if you get exactly 15,000 bonus. If you get some other amount of bonus with all the drop targets down, that might be a clue as to where the problem is.

- TimMe

One other thing I should mention. I think all of this discussion has been assuming you are on the first ball in play when you are testing the bonus. On this game, the bonus increases from 1000, to 2000, to 3000 as you move to a later ball-in-play. So you need to be on the first ball-in-play to ensure that the machine is set to score only 1000 bonus per pool ball.

At the bottom of the playfield, between the flippers, there are three lights to indicate what bonus score you will get for each lit pool ball. When you do the test to see if you get 15,000 bonus for having all of the drop targets down, please confirm that only the 1000 point light between the flippers is lit.

Thanks! - TimMe

OK, very good info, thanks. When you did the test with all drop targets down and the 8-ball triggered, you saw that all 15 pool ball lights were lit, right? I'm just checking to confirm that you don't have any burned out lamps on your playfield pool ball lights.

This is a fairly unusual problem, so some additional details about exactly how your game is malfunctioning would be helpful.

When all the drop targets are up, but you still get the 8000 bonus points, do each 1000 points get added onto the score quickly, or are you getting only 1,000 added every score motor cycle? The reason I'm asking is because on your game, the bonus unit should scan quickly (5 steps per score motor cycle) when no pool balls are lit. But, when the bonus unit scanner finds a lit pool ball, it should stop stepping, and the score itself should be added slowly, only 1000 per score motor cycle.

In trying to find the root cause of the problem, it would be helpful to know whether your 8000 bonus points are being added quickly (for example, 5000 in one score motor cycle) or if each 1000 is being added once per score motor cycle. It would also be helpful to know whether your bonus unit is stepping quickly (5 times per score motor cycle) or slowly (1 time per score motor cycle). I hope that all makes sense.

If you have the means to post a short video of the 8000 bonus being added, that would be helpful. If not, no worries.

Thanks - TimMe

Your description makes complete sense, thanks very much. The details you provided are very helpful.

Based on what you are seeing, the first thing I would check is the bonus score relay (I relay). On this relay, there are five switches. Two are NO (normally open), two are NC (normally closed), and one is make-break. I suspect that the NO switch that is the lock-in for the I relay is out of adjustment and is always making contact. One side of this switch has a yellow+black wire. The other side of this switch (with a slate+black wire) is connected to one side of the I relay coil.

According to the schematic, if the above switch is always closed, then the I relay will pull in as soon as the bonus scanning operation starts (that is, as soon as the ball enters the outhole).

The score motor on your game always provides a series of 5 pulses for scoring during each score motor cycle. For example, to score 500 points, this 5-pulse train would cause the 100 point score unit to step 5 times. The circuitry of the score motor can be wired so that a component will only receive specific pulses, rather than all 5.

The I relay being pulled in will cause you to get 1000 score during the 1st pulse of each score motor cycle, even though there are no pool balls down. Also, when the I relay is pulled in, the 4th score motor pulse will step up the bonus unit one time.

The I relay is forced to drop out just prior to the 5th score motor pulse, due to a motor 3C switch. That will allow the 5th score motor pulse to also step the bonus unit one time, which would explain why you are seeing two bonus unit steps per score motor cycle.

Note that when real bonus score is happening, the 5th pulse to the bonus stepper is disabled by a switch on the bonus score control relay (J relay). The J relay pulls in when the bonus unit scanner finds a lit pool ball. This would explain why the bonus scoring is working as expected when all the pool balls are lit, because in that case, the J relay is pulling for in every score motor cycle of the bonus count, which makes the I relay seem like it's behaving correctly.

Of course, the above is just an educated guess. The bonus counting logic on this game is fairly complicated. But, as far as I can tell, a stuck lock-in switch on the I relay would be a good fit for the specific symptoms you are seeing.

- TimMe

Great, glad you found it! For me, this kind of unusual fault is always the most fun to figure out.

The J relay is a six-volt relay that is energized by the same circuit that lights the pool balls in the rack on the playfield. In other words, the J relay uses each lit pool ball to detect that a given drop target is down (or in the case of the 8-ball, that the G relay is pulled in). The bonus stepper is what selects each pool ball lamp to energize the J relay, one at a time.

So, on this game, the bonus unit is used as lamp-scanning device rather than a counting device. The designer of this game, the brilliant Ed Krynski, used this same type of circuit on other games where downed drop targets scored bonus, such as High Hand. The six-volt relay was a cost-saving measure that allowed him to put just one single "target is down" switch on each drop target, instead of the usual stack of two switches (one for the lamp circuit, another for the coil circuit).

The description of bonus operation by ArgosySK is correct, although there are some additional things happening with the bonus scoring logic on this game, which is really rather complicated. I'll try to do an end-to-end write-up of how it all works and will post it on this thread.

Thanks - TimMe