Hello Guys,
The Williams HV replacement board project started life about five years ago when I bought a BSD at auction. It was in pretty poor shape with many bits broken and missing and the High Voltage circuit completely trashed - including the common problem of the actual printed circuit board being crisped to the point of crumbling. I had repaired many of these previously but this time the board had become conductive and no matter what I did it was realistically beyond repair.
After getting over the shock of the price of a replacement board I set about investigating the actual circuit and what was involved. It became obvious that the DMD voltage circuitry was actually separate from all of the signal processing circuits and was basically just 'tacked on' to the bottom of the DMD driver board. I made up a circuit at that time in my workshop and the machine has operated with my homemade board perfectly well for five years.
After reading Clays Pinball Repair Guides I became aware of a similar board available from the USA. Clay mentioned that it was a fantastic idea but pointed out that it used 205 sized fuses and also mentions that it could have LEDs to indicate voltages.
I updated my old design and included a test point for every voltage, LEDs for three of the voltages (technical reasons prevent using LEDs for the two very high voltages) and made sure I used 3AG fuses so that they are the same as all other fuses used in the machine.
I then made a new prototype and once satisfied all was OK I sent the files off to the printed circuit board factory and had the boards professionally made. I have only just this morning finished assembling the first production board. Parts have not yet arrived for the rest so they will be a few weeks away yet.
I fitted it to my machine this morning and it fired straight up. I have designed it using single sided PCB with very 'meaty' pads so that it will be easy for anyone to repair in the future should it ever need to be. The components are also spaced apart better than the factory board and are (in some cases) upgraded in specs so the whole circuit runs cooler. The orginal layout leaves a lot to be desired and frankly is a fire hazard!
Finished boards will be available as soon as the parts arrive. Some pics here showing the test points, assembled board and it operating in my game.
