Wildfyre MPU board repair

[Mr Pinbologist]

G’day all

Been heaps busy lately doing repairs on other peoples games, as well as doing some upgrades to my homemade VORTEX.. including a new sound board with speech! (maybe i'll do a thread about that little project later on!!) just need to find time to start on my Zac Universe that has been sitting there untouched for the last four months!! 

I got asked to check over and repair the boards out of a Stern Wildfyre by a mate of mine, and after seeing the work of others on here doing their own board repairs I thought id show some of the results of the Wildfyre MPU I just finished repairing.

As can be seen in the 1st few pics it had some pretty nasty corrosion damage!! Amazingly though the board still was able to boot up!!.. well almost, the seventh LED flash wasn’t happening due to an open circuit resistor (R113). Also note the two wires on the back of the board someone else had put there to get the board running due to corroded feed thru holes in the board.

Notice too, that the game ROMS are not in sockets, but soldered in has anyone reading this ever come across this before?? these look as though they were soldered in from the factory.

[Mr Pinbologist]

First thing I had to do was to remove all of the corroded components.. no easy feat as with this amount of corrosion as anyone who has ever done this will know! However some careful sanding with a Dremel with a small sanding disc attached made easier work of it. I sanded back some of the solder, then heated the joint while adding some new solder to help melt the old solder, most of the parts I just cut the leads to remove the part in question then heated the solder and removed the cut leg with tweezers. With all of the parts removed I  desoldered all of the component holes using an ordinary desoldering pump, then cleaned the traces with the Dremel.. being VERY careful not to sand thru the traces!!

 Also I had to remove the socket for U8, I simply put a series of cuts into it with the Dremel and a cutting disc, trying not to cut too deep. Then I simply heated each pin and removed them individually.
As luck would have it, I DID manage to damage a couple of traces which I had to repair later. I used strands of fine wire for this.

Sorry but I didn’t get any pics of the board with the components removed! But once I had the copper cleaned I sprayed on a couple of fine coats of printed circuit board lacquer to prevent the tracks from tarnishing up.

[Mr Pinbologist]

Soon as the lacquer had dried I started to replace the components, using new parts except for inductors L1 and L2, which were still ok so I cleaned the leads up and reused them. I used machined pin socket strips for the socket for U8. As mentioned before R113 (a 2k resistor) was open, and I didn’t have any 2k resistors I used a 2.2k instead. Note that if you change R113 to 2.2k you also must change R16 to 2.2k as well. As long as this is done the board will function normally.

Also with R140, a 20k resistor I just used two 10k resistors in series, as I wasn’t sure if I could change the value of this one. Another small change I made was for the transistor to drive the LED.. I used a BC548 instead of a 2N3904 as I didn’t have a second one of them to use. Notice the orientation of the transistor in the 2nd pic. A BC548 needs to be turned around opposite as the pinouts are different to the original.

Next I replaced the bottom two connectors J3 and J4. after that I was ready to test the board. initially when I tried it on the bench I wasn’t getting the third flash, meaning a bad U8 or its socket. After having a read thru Clays repair guide and finding the table for checking U8s connections I discovered I had no continuity between U8 pins 9/10 to U7 pin 6, which I quickly traced to a tiny crack in the print near U8 pins 9/10 that I repaired by soldering some fine wire (last pic). Fixing this had the board booting up correctly! (six flashes, no seventh without any 21volts on TP3 of course). All that is left to do now is to fit leads to remote mount that memory battery.

[Mr Pinbologist]

Next I decided to plug the board into a game just to see if it would boot up ok and light displays etc, (only plugging in J1 and J4) so I plugged it into my Dracula and switched on.. worked no problems!! Next I decided to plug in the sound board and switch matrix so I could run the self test and check and reset everything, again no probs.

 On an impulse I decided to clock up a credit and hit the credit button and launch the ball… fully expecting NOTHING to work/score the same… and… bugger me dead the gameplay/ rules were practically IDENTICAL to Dracula!! WTF??? I mean every single switch/target did the SAME function as the Dracula MPU!!

At first I thought that this Wildfyre board must’ve had Drac ROMS in it, so.. to prove a point… I plugged in a spare Alltek MPU that I have and tried it.. first I set it for Dracula and tried it, all good. Then I did a memory clear and set it for Wildfyre and tried again… once again EXACTLY the same.

 Incredible or what??!!

Oh well in any case the repairs to the original Wildfyre board were a success so I guess that’s all that matters hey??

Hope that this thread was of interest!!

Cheers.. Mitch

[63wizz]

Very interesting thanks for sharing your experiences with this board repair, I find these threads most interesting, as i like to have a go at repairing these things my self first, and it helps a lot to read of other peoples repairs.

Ian

[Strangeways]

I've only ever seen a CPU soldered on to a -35 Bally Board. I'd say it is a repair, but those do look like original masked ROMs.

Great work ! It is a fantastic achievement repairing one of these boards.

[Skybeaux]

You've done a nice job of repairing the board

I've seen game chips soldered directly to the board before ,but it wasn't factory ,just bodgy.
I wouldn't think that Stern would have done it from factory either ,but you just never know.

Several early Stern machines used the same game chips ,must have saved them money on programming costs.
Wild Fyre and Dracula...interchangeable
Cosmic princess and Magic....interchangeable
Stingray and pinball.....interchangeable

That's all i can think of off the top of my head

[Mr Pinbologist]

Thanks guys

Skybeaux, thanks for the info re Stern using the same game chips in more than one game.. makes sense now. I thought i was going mad when Drac played as normal with this board hooked up

Its the first time i've ever come across game ROMs being soldered directly into the board.. glad i didnt have to remove them!! sometimes its bad enough removing them when they're in sockets!! And i was glad to see it fire up and work pretty quickly. I started on this board yesterday mid afternoon, worked on it for a few hours then and finished it this morning about 10.30ish!!

[Skybeaux]

I know what you mean about removing original roms , a lot of the time the legs break off and stay in the sockets  .....i hate em!
I almost forgot this one , Lectranamo and Nugent use the same roms as well.