Credit where credit’s due
I had been meaning to take a look at it for some time and today I managed to solve the problem:
Between the coin mechanism and coin processing board in the pinball machine, there’s a mini PCB with an LED, a row of mini-switches an IC and a miniature potentiometer. I wanted to know what each of these parts did.
Originally the pinball machine came with three coin slots for three different coin denominations. These three had been reduced to just one coin slot able to take three different coins in my machine. The output from this coin mechanism was then taken to the mini PCB and the output of this board taken to the coin interface board of the pinball. So my assumption was, that this mini PCB took the data signal from the coin mechanism and converted it into coin pulses (the number of pulses being directly linked to the value of the coin inserted), which were then registered by the coin interface board on the pinball. But what was unclear to me was what each of the controlls, particularly the potentiometer and mini switches did.
So I carefully prised the PCB off of its mounting and discovered that it was a miniCredit V1.0 from a company in Germany called DoubleYou GmbH (an interseting name for a German company, especially in a country where the locals have a problem pronouncing the letter “W”). This information had been helpfully etched onto the PCB. The board was also copyright 1997, so there was a good chance I might find out more about this board on the internet.
Sure enough I found www.double-you.de. On this site was a product called the miniCredit, albeit in Version 1.1. A quick eMail to DoubleYou confirmed that the two boards were essentially identical and that the documentation for the miniCredit was on the company’s web page (and now available here).
Sure enough the bank of switches sets the number of credits per coin (of which there are only four variants) and the potentiometer varies the length of each “coin pulse”.
Another quick email to DoubleYou confirmed that for any other variants of the number of credits per coin, the PIC processor would need to be reprogrammed by them (at a cost of €15).