Hello All,

I'm hoping those with more experience than me can mentor me a little bit and check my thinking with a problem I am working through. This is on a Eight Ball Deluxe LE pinball with the -54 rectifier board. I picked this up recently and for some reason, many wires in the game were cut and then twisted back together (usually with electrical tape covering the twist). I repaired as many of these hacks as I could find and traced down any wires that seemed out of place. I then rebuilt every single component on the rectifier board because I found voltages out of spec. Just yesterday I was going through the test menu for the first time trying to find why I wasn't getting sound effects and I stopped on the solenoid test.

The game started doing the solenoid tests and the displays all went out when it reached #3. I did some digging today and discovered that solenoid #3 is for the knocker. So I traced the knocker wires and discovered that the previous owner had removed all traces of the knocker assembly and hacked together the power lead in to another circuit (coin door lockout solenoid). I guess he was thinking that that solenoid wasn't really needed, so firing that off when the knocker went off would be fine. It turns out it wasn't fine. I had missed it while fixing up their hacks. Because of the diode on that coil, the current was forced to flow back in to the rectifier board.

The green wire that the knocker wire was soldered in to went to connector J2 on the rectifier board. So here is where I begin to be unsure and would appreciate input. The current wanted to get to ground and complete the circuit, but it blew a few things along the way. It looks like it tried to cross the varistor and the fuse after going through the bridge rectifier. I'm not sure if the fuse blew because of that current, but regardless the varistor must have shorted and quickly wiped out the fuse. I'm also not sure why it blew this varistor at all, why not just go straight to the ground after going through the rectifier.

So that should cover the damage that was done by their hack (right?). I was thinking of removing that varistor to check if everything is functioning, but I don't fully understand what that varistor is doing, so I figured I should replace it instead of just remove it until the new one comes. I attempted to check the rectifier on that circuit, but I was getting weird readings and don't have a diode test function on my DMM. Based on my understanding of rectifiers, I figured I could check continuity between the negative and two adjacent legs. I wasn't getting any continuity even though I figured I should measuring in that direction. Same thing on both rectifiers, so I wasn't sure how to interpret that.

So thanks for reading. I am attaching an image from the schematic so you don't have to search. If you can, please let me know if I seem to be on the right track. Anything else you can think of would be appreciated also. Thanks!

Yeah, I'll have to look in to getting one. I ordered new bridge rectifiers because they were cheap and I needed to get the varistor anyway. I don't know why my picture didn't attach, I'll try again. But to answer your question, it was the 5A F4 fuse that is on that same circuit as the varistor that shorted.

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Well, studied the wiring diagram some more and I think I understand better now. What the previous owner had done was connect the power and ground for the solenoid together. The positive wire was run in series to the coin door lockout solenoid, which had me confused at first.

Does anyone know why a direct short like that would blow the fuse and varistor? Is it because there is to much current flowing to ground and pops the fuse? In that case why the varistor also? In any case, I thought those were the only two issues so I replaced the varistor and fuse only to turn it on and blow both of them again. I'm in a little over my head on this one, can someone give me some pointers? Could the bridge, resistor, or transformer on that circuit have an issue also?

Thanks in advance

The transistor may be blown, yes. I've had blown transistors before though and didn't pop a fuse or transistor. It must be something else that was brought on by this short. I only have one more varistor on hand, so I would like to troubleshoot or have good confidence before replacing it and trying again. Thanks for your input

Bump

So if the varistor shorted, most likely it got to much voltage. I checked the green/orange feed from the transformer for the +43 vdc line and got about 53 volts AC. The varistor that blew is rated to 60 vAC, so I'm still at a loss for what is happening. Can someone give me some things to check? Should I replace the bridge rectifier? If so, can someone explain why one of those being bad would give me my symptoms?

Thanks for the response. Yes, I put a new fuse and varistor in and it immediately blew both of them. The varistor didn't visually appear bad, but when I test resistance it's a dead short. I verified this isn't normal with a new varistor. Keep in mind that the voltages all checked out after I rebuilt the board and didn't have an issue until I activated the knocker hack in the solenoid test.

I checked voltages while troubleshooting this issue initially when it shorted, I was getting 0 volts for the 43 vdc feed as expected due to the blown fuse. I'm assuming that when you said f5, you actually meant the fuse for the 43 volt feed, which is f4. I'll remove that fuse and varistor and check those voltages tonight along with taking pictures of the front and back of the boards. I'll also check out the resistor in the circuit.

One thing I noted before that I still find strange is that when I do the diode test on both bridges, I get very strange readings. I want to try a different multimeter because mine is difficult to understand. I checked a diode on the bench and those readings made sense, but not the bridge readings. I think I'll check one of my other games and compare. Both bridges had the same strange readings though and the 5 volt feed seems ok.

The part number for the varistor I'm using is

V100ZA15P

It's from gpe which maybe explains why he is sticking up for it, haha. As he said, it's rated for 60vac or 81 vdc.

Sorry I haven't responded until now. One of the comments mentioned checking the wiring because of the weird issues I am having. I didn't do that at first because I believed the seller and the voltages seemed to check out when I tested it. Well...i should have known with how shoddy the hacks on this game are to check closer.

I'm attaching a picture of what I found when I investigated j1 for the transformer. I don't fully understand what exactly this setup would do to my voltages, but at the very least it needs corrected. They have the jumpers way wrong and are feeding voltage to the 100 volt, 115 volt, and 120 volt inputs to the transformer. There was also no common jumper for the transformer.

I'm also attaching the pictures of both sides of the rectifier board. Nothing jumped out at me and everything looks to be soldered properly. I did find that the positive and negative for the knocker were still connected and perhaps the mpu was still stuck in the test mode for the knocker, causing the fuse to blow again. Not sure on why the varistor went also.

I checked for voltage on the other side of the f4 fuse and found none when the fuse was pulled. So I'm going to fix the jumpers for the transformer and isolate the knocker wires before replacing the varistor and fuse. While replacing the fuse I'll also check the resistor in that circuit and investigate the bridge rectifier farther.

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Interesting. So the common jumper isn't necessary then? The way I pictured the transformer input side was a bunch of tabs at varying number of turns and you fees the power to the right location. It looked to me like the current setup has the line voltage going to several of those tabs instead if just the 115v one. I haven't verified this with continuity though.

Thank you very much. I was actually numbering the connector differently which is why I drew my picture the way I did. I was going left to right from top down. That makes more sense now

The game is working again. I replaced the varistor and fuse again after removing that short. Thanks everyone!