The scan bonus unit of CANADA DRY / TARGET ALPHA / SOLAR CITY
Sorry for the translation by Google...
This article is the compilation of several posts from Flipjuke, Retroflip and Pinside, as well as from my personal experience.
I would like to thank Jean-Luc Therville, a French collector, who, a few years ago, gave me a better understanding of this damn bonus unit.
1 / How the bonus unit works
This tutorial is intended for a programmed 3-ball game.
On the 3 games concerned by this tutorial, Gottlieb installed a scan bonus unit and added a 6th pulse per sequence (4D motor switch), just after the 5th pulse of 4A.
On the motor sequences chart of these 3 games, there is an error regarding 4D stacking.
It is not at the start of the sequence but at the end of it, between the last action on 4A and the end of the engine sequence.
There is also an error in the motor switches list.
4A inside switch is well assigned to the operation of the Add Bonus Unit.
For the 1st and 2nd ball, the bonus unit receives 6 pulses (5 pulses of 4A + 1 pulse of 4D), the 1000 points relay L receives as many pulses of 4A + 4D as there are fallen targets.
So during the motor sequence, the bonus advanced 6 notches and the 1000 point relay L counted from 0 to 6000 points depending on the number of fallen targets.
So, for a perfectly adjusted machine, the unit bonus counts completely in 2 sequences (6 notches X 2) + a ½ sequence (3 notches) = 15 notches = 5/6 engine revolution.
In 3rd ball, the opening of the Normally Closed contact of K shows the 2D and 3B contacts which are in series with 4A.
This has the effect of giving only 3 pulses per sequence (4A + 2D, 4A + 3B, 4D) on the bonus unit while the 1000 points relay L still receives 6.
And so 2 impulses for the 1000 points relay L (and 1 on the bonus) give 2000 points per target.
Clearly, per motor sequence, the bonus only receives 3 pulses while the 1000 points relay L still receives 6, the bonus unit counts completely in 1 motor revolution (3 notches x 3 sequences) + 2 sequences (6 notches ) = 15 notches.
The bonuses are counted through the operation of "Bonus score control relay" relay G via 2 essential switches, the G relay lock-in switch and the Normally Closed switch of the 15th position.
Finally, the bonus unit is reset to zero with each new ball, via a switch of relay P.
2 / Cleaning of the various elements constituting the bonus unit
The counting of bonuses on the Canada Dry is very precise !
On the one hand, a perfectly functional unit is needed mechanically, no downtime or skating, and on the other hand an efficient counting of 1000 points (L relay perfectly adjusted).
If the 1000-point relay L has a tendency to remain stuck after an impulse or if its motor contacts feeding it are clogged (especially the 4A which is close to the motor cam, and which has the potential to pick up a lot of dirt and fat), there will be anarchy in the count.
If the bonus unit jumps or stalls at times, there will also be anarchy in the scoring.
All this to say that it is necessary:
• Perfect cleaning and adjustment of the 10 + 5 switches of the drop targets (the switch must be closed when the target is shot)
• A 1000-point L relay, properly adjusted and perfectly cleaned switches, especially those with large pads,
• The 6 motor switches perfectly adjusted and cleaned: 4A (inside), 4A (2nd switch), 4D (inside), 4D (2nd switch), 2D (2nd switch), 3B (2nd switch),
If the transformer is set to High, the motor runs faster, which confuses the last 2 pulses (the 5th of 4A and the only of 4D) if the 4D contact is incorrectly set.
This 4D contact must be correctly adjusted, it must close AFTER the 5th impulse of the 4A sequence and BEFORE the start of the 1st impulse of the NEXT 4A sequence.
• Unbroken motor contact blades (particularly the 2D which is often broken and which makes the count disturbed in 3rd ball),
• The perfectly effective set of rivet / pad contacts:
That is to say, well curved pads and not flat when worn, pads sliding perfectly in the guides, clean rivets not hollowed out by wear, a very flexible connecting wire (bridge between the two pads) (not rigid) so as not to influence the sliding of one shoe in relation to the other,
• Perfect adjustment of the three 15th position switches, located behind the bonus unit, in particular the one involving relay G, this contact having to remain closed throughout the bonus count cycle,
• Perfect operation of relay G "Bonus score control relay" which must remain closed throughout the bonus count cycle (in particular the G relay lock-in switch and the 15th position switch mentioned above),
• Perfect functioning of relay K "Double bonus relay", for the counting of bonuses in 3rd ball.
3 / Adjusting the rotating cam
The ZERO position of the unit bonus is indicated by the intersection of the yellow wire and the yellow + blue wire.
Wedge the rotating cam in ZERO position, on the 2nd outside rivet (see pic below), the cam can however be shifted one notch to the right, on the 1st outside rivet; without any impact for the bonus count, since the system is scanning.
4 / Adjusting the 15th position switches
These 3 switches must be particularly cleaned and adjusted when restarting the pinball machine, because they are not easily accessible, once the playfield is vertical.
When scanning the rotating cam, it is imperative that the 2 outer contacts remain perfectly bonded throughout the scanning (beware of vibrations), otherwise the count will malfunction.
From the ZERO position and during the ENTIRE scan :
In the LAST position :
5 / Typical issues
• Slow countdown
The classic case of many Canada Dry and Target Alpha which are never properly repaired, due to lack of knowledge ...
15th position switch and G relay lock-in switch go the green path when fully functional.
If the 15th position switch and/or the G relay lock-in switch come off during the bonus count, the electrical path will be irretrievably taken by 2 additional motor switches (red dotted path), making the count very slow.
• Generous or miserly count as a bonus in 3rd ball (if game set in 3 balls)
This failure is recurring, you have to have a careful eye to find it !
Indeed, everything is based mainly on 2 motor switches, 2D and 3B, and particularly on the formed switch blades.
The recurrent failure is located at the level of the 2D formed switch blade, which suffers particularly during the many cycles of rotation of the motor.
It often happens that it's broken and then replaced by budding bad repairmans !
Below are 2 pics with the GOOD 2D formed switch blades :
This is what we can find !
I actually had some scoring issues recently when restarting a Canada DRY.
Indeed, the 2D formed switch blades seemed to correspond visually to a normal formed switch blades (ref A-9349).
But it had been manufactured without respecting the correct spacing, which caused a bad counting.
We can clearly see the differences between the 2 formed switches blades.
Please feel free to liven up this post if you have any anecdotes to back it up !