Hi all, I've searched for anyone having a similar issue but no luck, so hoping someone can shed some light.
I've got an Eight Ball Deluxe Limited Edition that was working fine for months. Then had a display issue which led me to start checking voltages back through the Solenoid Driver Board and then back to the Power Rectifier Board. I sorted the display but had found that TP3 on the rectifier board was reading 15.9V when it should be 11.9V. The game was running, so although I had a bad feeling (TM), I played on.
Then fast forward to a few weeks ago and the game wouldn't boot. The MPU doesn't reset, so I get no flicker and no flashes. I've probably got another issue there now, but that's for another time. I checked the voltages again and found 48V at TP3! I've added the wiring schematic picture to this post for your reference. My immediate thought was that there must be something wrong with the diodes CR5, 6, 7, 8, but if you look, they're fed with the two blue wires from the transformer and get only 14.2V. So then I thought it must be a short and I went over the board time and time again, everything was as it should be. So I started taking components off like the BR2 Bridge Rectifier which feeds the TP5 which should be 43V, as the similar voltages seemed to point to that. Anyway, went down a rabbit hole there with pretty much everything off the board, fuses out and still getting weird voltages where they shouldn't be...
Fast forward a couple of weeks and I picked up a Centaur 2 - same cabinet and same power rectifier board (well the EBD has the rev B but they're basically the same?). So I checked all the test points in the Centaur and they're all perfect (so it's not my multi-meter) then I pull out the board and put it into the EBD, only connecting up the J5 and J6 from the transformer (nothing continuing out into the machine yet, until I know the voltages are right)...
I checked the test points... and got 45V at TP3 !?!?!?!? How is this possible, it's a different (and just tested as working) board?!
Now I know some of the voltages can be a bit different if you don't have the outputs connected, but back in the Centaur this board was reading fine with just J5 and J6 (the power in) connected. Now it's got the same issue as the other board when it's moved to the EBD?
I should point out that I checked the voltages out from the EBD transformer by sticking the DMM probes into the J5 and J6 plugs, they were all perfect. I also checked the voltages on the board at the points between CR5-CR6 and CR8-CR7 where there is 14.2 VAC as expected. I think this rules out an issue with the plugs (I checked the same for all the other points where the AC from the transformer comes into the board). I also compared that the wiring of the plugs from the transformers are identical between EBD and Centaur, and that the plugs aren't damaged and did continuity checks between them looking for a short circuit between pins in there.
So in summary everything looks fine, right up until TP3 where it suddenly gets 45V.
The only thing plugged into the board between the machines is J5 and J6 - nothing else. So if there's a problem in EBD it must be coming from the transformer? The transformer really isn't under any load, is that a thing that transformers can provide different voltages when at rest or under load and does it apply here?
I have tried just plugging in J5 or J6 on their own, here's the results, do they make any sense?
Just J5: TP1=0, TP2=195, TP3=2 (should be zero), TP4=7.5, TP5=47
Just J6: TP1=8, TP2=12 (should be zero), TP3=20 (great, not 45, but?), TP4=4.1 (should be zero), TP5=0
In writing this, I've had an idea to put something like a cloth or some wood down underneath the board just to make sure nothing is touching that metal plate the BR's are normally thermally pasted down on to and somehow conducting current from one place to another. I'll check that and update this tomorrow.
Thanks for reading and all suggestions very welcome.