I have been troubleshooting my NGG for over a month and can’t figure it out. Nonetheless, I have some form of hack on my wiring from j2 on the 8 driver aux board to the power driver board I want to unwind

Can someone take a pic of the connections between j2 and j139 and j137?

Thanks in advance

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Yeah I figured that but I have something completely different as my smaller board does not connect as listed in the schematics . When I trace things out by schematic it looks like there are 2 wires going to one spot on the connector on the main power board which i definitely don’t have. I’m not certain if it matters. I’ll just work and figure things out. Thanks for the suggestion.

I'll post a pic later. Thanks for your comments. i wrote my prior note after having a few drinks from my phone and away from my machine and was afraid it did not really show appreciation for your input as well as respect to the community. I am especially grateful that someone as knowledgeable as you has taken interest.
I have been working on a problem for so long that part of me wants to figure the rest out on my own but the other part of me wants to get to the problem finally. I am not certain the smaller driver board is the answer but with the alternative connections I figured I would take a look. I think those cables are really just grounds and power to the small board and I just started troubleshooting this board and i think I can do some simple things first before rebuilding the connector. Not that rebuilding the connectors would be difficult, but I am thinking maybe the reason the connector was rebuilt is that my games main driver board has issues and this was a workaround. At present, I have another main driver board in the game to eliminate that board as the source of my issue.

My issue has been that the right popper randomly goes off during play and the right upper flasher as well as the normal thumping sound indicating the ball will be released to the playfield goes along with it. If I unhook the solenoid, it still continues but without obvious activation of the solenoid, if I unplug the mechanism, it stops everything initially making me believe it might be an opto issue despite no flickering or any way to provoke the issue in the switch matrix nor any other problems with all the other switches , however after replacing all the optos, the connector, the 10 opto board and all connectors leading to the opto board the issue persists. also when jumpering the switches pins on the opto board it still persists. I swapped in a new RD cpu board, I have tried 2 different main driver boards from my other machines, and I replaced all the ribbon cables and the CPU Rom all to no avail. I also tested all diodes and replaced just in case about a third of them on all switches. I activated all switches while in switch test mode and was unable to create any issues with the opto in question.

It looks like the 8 driver board controls the right upper flasher so I might look at the schematic to see if it is possible that a faulty 8 driver board could cause this or more easily just disconnect the connectors to the flasher and see if the problems follow, which I have yet to do as simple as that is.

Attached pics. The 8 driver board is connected to connector j134 and j136

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Have you considered a problem with the +12VU (unregulated +12V circuit)? This is used by the 16-opto board as well as the Auxiliary 8-Driver board. Often, modifications (mods) to the system tap this as a power source and this causes an excessive draw on the circuit and results in the voltage level sagging. When this happens, it can interfere with opto functionality.

I have considered this as voltages at connector to right upper opto is approx 11.5 volts but figured swapping in 2 different functioning power driver boards and a new opto board might take care that. That is an assumption however and you know what they say about assumptions.

Oh yeah and I have no mods

I’ll look through that today if I get a chance but if I’m gonna work on a board it won’t be the one I have on machine now as that was entirely functioning in another game of mine. I wish I had a bench tester for boards as it would make things so much easier. Maybe in future I’ll build one or something

I wonder if I could hook up an old 12 volt power supply directly to the pins supplying power to the optos in question and see if problem goes away. I think I have one of those possibly lying around from my led light strips

Bench testing is good for logic functionality but doesn't place the load of the machine on the boards. I have tester boards available but there are also other manufacturers that provide this testing functionality. It really depends on what you want to test and how you want to test it. These testers are good to answer the question "is it on the board or is it in the playfield?".

Certainly tester boards come in handy for figuring where the issue is coming from, thus why I also swapped boards in from other machines (poor man’s tester board). Once you know where the problems lie you can narrow down the electronic issue

For me, Bench testing would just make it easier to test each component for things like AC ripple and might make it easier to rebuild the flawed components. so if I swap out a capacitor and the voltage is still low I can go to the voltage regulator etc. without having to pop it back in the machine which is a bit of a hassle and a harder work surface. If the voltage is low not under stress, it certainly will not perform under stress

I have not done the quantity nor quality of work that you have by any stretch so I may be wrong, but that was my thinking

Also, the aberrant behavior of my NGG occurs even at the start of the game even before I plunge the ball often so I don’t think my system needs to be placed under much stress to figure this one out. I’m gonna work on getting my voltage up at the optos and see if it changes things. Would be nice to eliminate that as a potential issue

I have about 140 millivolts of ripple which I think is reasonable. Voltage into the opto board is approx 12.5 volts but down to 11.5 at connector. It is a brand new opto board and I repinned all connectors from board to opto. Test point 3 voltage 12.6v.

I’m going to have to continue to ponder this one

Swapped in new c8 and voltage without connectors on tp3 was 13.5 but dropped to 12.5 with connectors plugged. Seems like a pretty fair drop but I guess it is unregulated. Has not fixed my problem though. I’m going to figure this out sometime somehow. I feel like maybe I am just missing something stupid

Are these what u wanted?

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This was posted 5 years ago without an answer. Mine does this occasionally, not certain if it is just after my playfield was up but anyone else have this happen?

I have continued to very sporadically try and fix a spontaneous firing of the right upper popper and white flasher which I have described previously and can link to later if desired. nonetheless in my research many years ago in rec games pinball site it was posted that the resistor R51 was different on NGG under playfield opto board. The author of this post suggested in a later post that this could potentially cause abnormal opto behavior. Below I have a pic of the post and my board. Anyone know anything about this potential difference. Anyone have any idea what their original resistor is. Also has anyone used an aftermarket under playfield opto board with success on their NGG?

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