Tuesday, October 24, 2017

Building a Seeburg Wall-O-Matic Interface (Part 2)

Procuring a Functional Wallbox

Providing Power

Before you can do very much with a project like this, you need a way of powering up the wallboxes. These things don't run off the mains, nor do they use DC. Rather, these devices run off 25VAC. While you likely don't have a power supply just laying around that can provide this, its pretty simple to assemble one. You really just need an appropriate transformer and a few (optional) support components. This then connects up to a terminal strip right inside the wallbox itself.

In my setup, I used the following components:
I just wired these together as shown in the above schematic, using some heat shrink tubing and electrical tape to cover up the exposed contacts. Specifics aren't all that important here. All that really matters is that you get approximately 25VAC on the output, and won't fry something if there is a short.

 (Note: I don't actually have the rocker switch in this version, as I just used a switchable power strip. I do plan to add one on the final version.)

Okay, now to get started...

Seeburg Wall-O-Matic 200

This journey began with the acquisition of a Seeburg Wall-O-Matic (V-3WA) 200 from a rather nice eBay listing. It appeared clean, in good condition, chrome intact, and with the key. On the surface, it seemed like everything I needed to get started:

Unfortunately this wallbox basically sat untouched for a few weeks, since I still had to buy the necessary components (shown above) to power it up and I was preoccupied with other things at the time.

When I finally powered it up, the first thing I discovered was that multiple light bulbs needed replacing. That much was no big deal, so I just ordered them off Amazon (#51 and #55 bayonet mount light bulbs). I then discovered that the electrical contacts were dirty, the mechanics needed a little fiddling, and it didn't seem to be working correctly.

Thankfully it wasn't too hard to find the repair manual online. Of course it was written in 50's speak, and it was sometimes hard to match the terms and illustrations to what I was seeing inside the actual device.

I spent the next week or so in a state of constant frustration. I replaced the bulbs, cleaned all the contacts, tried to adjust and/or understand what parts of the mechanism I could, kept cursing at the DCU ("dual credit unit") that I was afraid to disassemble, and eventually sorta got it half-working. I got it to the point where I could manually toggle the coin switches and punch in a selection. Of course it would get stuck part-way through the signaling cycle half the time, and I'm not sure if it worked consistently with actual coins. (It was also dirty enough that I felt the need to wash my hands every time I was done fussing with it.)

From all of this, at least I learned quite a bit about how these devices operate. These things were designed in an era that pre-dates "electronics" as we know them, and are electro-mechanical in nature. They use a complex assortment of gears, cams, metal strip contactor switches, motors, and solenoids to accomplish what you'd do today in a single $0.50 microcontroller. (Even if it was only the 1970's, chances are you'd do this with a small assortment of transistors and logic chips.)

Eventually, I decided it was in my best interest to give up for now. I didn't feel comfortable disassembling the parts that needed the most attention, and I really didn't want to focus all of my energy on this stage of the project. So I decided to just go ahead and actually order a known clean/functional unit, from a dealer that actually specializes in this sort of thing. I can always return to this unit later, and it'll make a nice display piece regardless.

Seeburg Wall-O-Matic 100

This journey continued with me ordering a Seeburg Wall-O-Matic (3W-1) 100 from an actual retro equipment dealer. This time at least I knew I was getting something that had been cleaned and lubricated on the inside, in addition to being in good condition on the outside.

Okay, the buttons could probably use some restoration or replacement, but the rest of it looked excellent. Especially on the inside...

When I powered this unit up, everything magically worked. Okay, I might have had to fiddle with the coin switches a little bit, but those are easy to knock out of place simply by removing the title strip and coin rejector assemblies. Regardless, I was quite happy. I now had a fully functional and reliable wallbox I could use as a foundation for the next stage of the project.

Besides simply being clean, lubricated, and functional, this model had another big advantage over the 200. Its mechanism is a lot simpler. It doesn't have an overly complex "credit unit" in the middle, and I don't think I'd be afraid to try disassembling any of its mechanism if I needed to.

I did later discover this unit had a few modifications done to its coin mechanism, however. It doesn't accept dimes (only nickels and quarters), two of the coin switches were tied together, and one of the coin solenoids was disconnected. I wish these modifications hadn't been done, but they're not a showstopper. I can easily live with them. They basically mean that the device now has only two credit states: A dime adds one song credit, and a quarter adds two song credits.


Repair manual for the 100
Repair manual for the 200

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