Thursday, October 1, 2015

Central Park: getting it running!

Like a rat in a cage desperate for a food pellet but wary of the button that last shocked her, I stood pensively by Central Park.
I needed to play!!!!!!!!!!!

As oft with line voltage issues, I bring in external help to assist and verify.  I've been zapped a few times, and I want to limit it as much as possible.  We don't need any after school specials about how kids should avoid getting involved in pinball for fear of death by electrocution.

We put a lede on the door frame and started testing to find the short.  At first I thought the short was before the door connector, but it turns out it was the coin chute shorting to the metal frame.
Let that sink in:  metal coin chute, metal switches, metal door, and LINE VOLTAGE RUNNING THROUGH IT ALL.
I am going to be disconnecting the coin door wires altogether.  No point having extra line voltage running to the front.
As well, removing the slam tilt connection from the coin door.  Also line voltage.
I will just leave it at the start button.
This is a 1966 game.  No one cares for classic coin action startup behaviour and such, let's just get playing!

the jammed coin switch
In addition I took out the single piece of dried electrical tape buffering the metal button to the line voltage switch stack.  Replaced it with 5 layers of thick fresh electrical tape, and realigned the fish paper.
Once the jam was cleared the front was no longer electrifying!
I still want to do those mods to reduce the chance of future issues.  As it sits, it is one kid with a quarter away from fudging their way to an electric shock.

Oh hey, did I mention we got the game working?

The last barrier to getting the startup going was the "ball on" stack. 
A solenoid pulls down a lever that lets all of the balls queue up to the shooter lane.

here is how it was when I started:
how we found it, resting position

bent in to shape
At the bottom of the photos you can see the metal bit that pushes the stack outward.  That pulls out and closes the stack, and lets the balls in to play.
That solenoid is buzzy and stays active until any points are scored. (It's locked until the 10 or 1 point relays fire)

oh right the credit unit

One other thing required to get it running properly:  this buggy little credit unit.
Not only is the clock spring wound around the post on the cog, but there is a DELIBERATE short such that it will continually decriment the stepper past the zero position.
Let's look at one special detail in that photo:
well hello dancing wires

You can see the two wires at the front/top are BRAIDED TOGETHER.  When the switch hits zero position, the gap opens and thus the solenoid is not allowed to lower it any further.  Braiding the two wires together means it will ALWAYS be able to move past zero position, which is why we ended up with the overextension of the stepper, and a short amongst the switch plates.

Someone did this on purpose.  They are my nemesis.

With that all taken care of, the game played!

Some problems:
On the left (yellow) bank, numbers 1 and 2 were not going out when hit.  Under the playfield I closed those relays manually and they locked on.  (each number, 1-10, has their own relay.)
After that, those numbers work A-Ok.  They always say that the best maintenance for an EM is to play it regularly, and I think this is one of those situations.

After that, one big thing that immediately stood out was that when the green (right) number bank was completed, everything reset.  The left, when completed, would not reset.
I took a look at the bank of 1-5 relays and thought there might be a switch, like Surf Champ, where if all are on, it indicates that the bank is complete, triggering something else.

Here is the bank of 1-5, under the playfield.

these Gottlieb banks have these handy screws that allow you to readily rotate them to a more serviceable position.

I saw this odd switch poking at relay #2.  I had a very hard time seeing what it was up to though, even with the grace of pulling the relay bank outward.
well hello switch, you look like you do something!

from the other side, I added probes to make sure I could test the switch connection
So this switch had issues.  It was not closing when the #2 relay dropped, so with a bit of cleaning and bending I got it working.
Closed the machine, pressed start and...  BUZZZZZ the coil was locking on!  Easy fix though:  I had forgot to resecure the screws for that relay bank.  duhhh
That taken care of, game started properly.
And while this wasn't the fix I needed, it did help.

That odd switch I found was just used by the X relay reset sequence, so that game was no reseting certain cases a little bit better.

So there are still a few big issues:
The 1-3-5 rollovers just resets the yellow./left bank outright.
some of the rollovers lights all available, instead of just a single.
The left/yellow bank doesn't reset on completion, ubt the right/green resets all on completion.
the #7 light socket has issues, probably needs to be replaced

 so, plenty to look in to!

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