Sunday, January 27, 2013

The Modern Firepower Pinball Project - Prep for Wiring

In prep for wiring the playfield, I'm test fitting all of the various circuit boards and components onto the underside of the playfield.  I have to find a place for three LED-Wiz output driver boards, one U-HID switch input board, one Pinball Solenoid Power Driver board (of my own design), and a USB hub to tie them all together.

From the original design concept, I intended to install the circuit boards directly to the playfield.

It is not a requirement that I install any of these components to the playfield.  Alternatively I could have installed the circuit boards in the backbox, like a normal pinball machine.  To install the boards in the backbox would require me to fashion up several wiring harness connectors, as there would be around 150 wires connecting to the playfield.

But since my circuit boards are so small and fit on the playfield, I will only have 3 wires connecting to the playfield:  The 50v power supply, the 5v/12v power supply, and a single USB cable.

Now that's the definition of Modern.


I finished my new Solenoid Power Driver circuit board design and submitted it for prototyping.  I used ExpressPCB.com, a company that provides you with free PCB design software, though the software is restricted to only work with their service.  I found the software very easy to use for the hobbyist.  I should receive the finished prototype boards later this week.  The nice thing about ExpressPCB is that it allows you to print out the design to full scale.  This is great if you want to etch your own boards, which I did for my first prototype.  Printing out your circuit also allows you to test fit the components, which was crucial in this design as I packed the components very densely on the circuit board.

While I'm not etching them this time, I did print out the board so I could find a place to install it on the playfield.

Test fitting the five circuit boards and the USB hub onto the underside of the playfield.

Most of the boards fit easily, but I did find it to be a tight fit for the LED-Wiz next to the slingshot.  Nothing I can do about that, so I'll just have to deal with the tight fit.

Not only will having the circuit boards on the playfield minimize wiring to the backbox, it also minimizes wiring on the playfield itself.  Wires connecting to the lights only have to go to the nearest LED-Wiz, not over the entire board.

After figuring out where the circuit boards would live, I sketched out the wiring plan.  With a few exceptions (50v solenoid connections and 12v flasher bulbs), it's not important which wires connect to which LED-Wiz ports, so sketching out the wires is only about keeping the wiring neat and tidy.

Prior to wirinig, I sketched out the lighting wiring paths to the closest LED-Wiz.

The playfield image showing the light positions is actually from my pinball program.  While some of the lights are not shown in their actual location (the six arrow lights for the middle stand up targets), this image gives me a decent representation of the light locations.  I reversed the image before printing it so that it matches the underside of the playfield.

On the LED-Wiz in the middle I divided the board into 4 segments, these are the 4 separate banks for the Bank Select Voltage feature: each bank of 8 outputs much share the same voltage.  Two banks connect to the Solenoid Power Driver and operate at 50v, one bank goes to the flasher bulbs and operates at 12v, and the last bank will run at the standard voltage for the rest of the lights.

This image is my second wiring draft, and I will probably do a couple more sketches before I'm happy with the layout.  I see a few small wiring path changes I can make to keep the wiring extra tight and neat.

I'll also sketch out the switch wiring paths and the solenoid wiring paths.  Once I've got my gameplan together, I'll start wiring:  Switches first, then lights, then solenoids.

Wiring will start today, and my goal is to finish the wiring this week, though I've probably grossly underestimated the time it will take to run 300 wires (including ground wires).

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