Wildfyre driver boards repair/upgrades

[Mr Pinbologist]

Hi again

Just thought I’d post a few pics of a Stern Wildfyre solenoid driver/voltage regulator board that I just repaired… nothing out of the ordinary here… the usual blown high voltage section and ground mods needed but I just thought I’d show a couple of little mods that I like to do to these boards.

First pic shows the completed board. It still had the original 11’000uF cap fitted for the 5volt regulator section so it had to go of course, replaced with a 15’000uF cap.

Next I replaced all the parts as necessary in the high voltage section, all three transistors, both diodes and only one ceramic cap, (only one measured bad when tested, the blue cap is the new one).

Notice the 2nd pic, I used two zener diodes in series to replace the original140volt zener. 140 volt zener diodes are hard to come by so I used a 75volt and a 68 volt in series, giving me a 143 volt zener diode. I’ve used this arrangement many times without problems. Also I replaced R51, a 22k 1/2watt resistor which is usually burnt on these boards, with a 1watt type.

[Mr Pinbologist]

Another change I like to make to these Stern boards is to add a fuse holder for the high voltage for the displays on the output side of the regulator. I know the later Bally/Stern boards have them fitted, and that some later Stern games have a fuse fitted to the back of the hinged lamp/display panel of the backbox, but I wasn’t sure if Wildfyre had one fitted to the panel and added one anyway. And besides it will be useful to have a fuse on the regulator board for another mod I have planned for the future.. a protection circuit for the displays in the event that the regulator section shorts out, feeding 230volts into the displays!! The 2nd pic shows the back of the board, showing where I added the fuse into the circuit (red wires).

Blue wires are for the ground mods and the yellow wire (already fitted by someone else) linking TP1 to TP3 for the 5 volts.

I tested this board in my Stingray game.. all good except for one solenoid driver transistor that needed changing.

[Mr Pinbologist]

And here’s the Wildfyre lamp driver board running on my test jig.. just a couple of SCRs had to be replaced

[Strangeways]

Good work Mitch - I love your test fixture 

[shansta]

Ditto to that! 

This is all over my head at the moment - love that test rig - finding out what is wrong is what stuffs me usually!