I wonder if those schematics are correct of if the later MPU-2 boards were modified with a jumper on the back of the board to pin 9 on J4 as that pin doesn't seem to be connected on the board I have here. Maybe someone has a picture of the Cyclops board and can confirm the way it's wired. I'd like to support that if possible.

Hmm, to add to the confusion both MPU-I and MPU-II schematics (bottom right) show digit 6 (7th digit) is on MPU connector J3 pin 18.
The wiring diagram of the display cable is where it says MPU J4 pin 9
I don't see J4 pins 7 - 9 mentioned on the MPU board schematic.

I just looked at the Sharpshooter II schematic and it is similar to the Cyclops schematic for the displays. Found a picture of a Sharpshooter II with an extra wire going to J4. If so maybe the MPU has a jumper on the back from J3 18 to J4 9. Maybe someone with a Sharpshooter II can post reference photos of the back of the MPU to confirm.
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See here:
https://pinside.com/pinball/forum/topic/game-plan-mpu-repair-a-shotgun-guide-w-pix/page/5#post-4544412

Anyone have a new or clean working sharpshooter mpu board for sale? Thank you!

Perfect! All makes sense now.

I was able to revive the original MPU for my Sharpshooter but I’m still working on a new upgraded version. Once it’s done I’ll be making more.

I am working on a Super Nova I bought recently, and I think the space station mechanism is missing the components that stop the wheel in the proper orientation. Would anyone with a Super Nova be willing to take photo of theirs?

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I found a photo of the back side on ipdb. I found the rubber part in the coinbox, and the spring was serving as the playfield fuse!

Now what I need is list of rubber ring sizes. Anyone?

Does anyone do board repairs? I have a game plan old Coney Island all the lights come on but can’t get the game to start playing

Any pictures of the MPU to show how bad the damage is? I just rebuilt a couple for Sharpshooter which use the same board.

Robotworkshop sent message

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Looks repairable and similar to the last couple boards I fixed. All the green ceramic disc caps should be replaced as well as the DIP sockets in the corrosion area. Have some repairs in the queue to clear out but after that could look at it.

Not too bad at all! I’ll just have to reflow a couple of joints and I’ll be up and running in no time. B4F876C7-882D-49CE-9FBE-4B843636B34D.jpeg

What is everyone using to replace the flipper plungers and links? Or at least the links? The links on one of my games is totally worn out.

Has anyone noticed a flash of the lights on your game when you turn it on? I’ve got two Sharpshooter games side by side. One of them will more often than not have the lights turn on, all turn off for a fraction of a second, then come back on and it all plays normally. It doesn’t seem to be an MPU issue as I have swapped them between games. Just haven’t isolated it yet. Going to start unplugging the other boards to see if any of those may cause it.

Oof. Busy working on this the last few days and not done yet. 9647FBEF-536F-480C-8E7D-37770054CCA9 (resized).jpeg

Good to know. I feel like this one is going to work out, but I still have time to ruin it.

And this is fully assembled now. We are adrift in a sea of bodge. I'll repair the power supply tomorrow and see if this is able to boot up. E4DBA413-6F55-4325-867F-405BEB6185E4.jpeg

I've sent echo lake a couple messages as well and very eager to send funds for a proven product.

I wonder if leds would cause this if installed?

Yup, I sent him a few emails a year and last one was a few months ago. Doing it again now.

Echo lake is no longer Making boards, he sent a reply that a different guy was taking over with a board that’s going to be made in China to keep costs low

Both games still have regular lamps for all the controlled lamps and most of the GI. One has LEDs for the GI behind the back glass. Good suggestion but I don’t think that is it.

On the game exhibiting the issue I did notice a large AC ripple (.4 volts AC) on the main filter cap so I’m sure that is toast. Replacing that today to see if it clears up the issue. The other machine shows 0 volts AC ripple.

Both of the original MPU boards for my Sharpshooter machines are rebuilt and working well. Only issue left is one isn’t saving the scores after being powered off. Both have a 1N5817 blocking diode with an off board holder with 3 AA lithium Energizer batteries. I’d normally run NVRAM but these boards use odd chips so staying with batteries. Have a few parts on order to see if I can resolve that last issue.

Curious to see what the solution is for your board. I had a devil of a time trying to get my original MPU to save scores. It will work intermittently at best, never could seem to come up with a solution for that one.

I still have one more original MPU-2 to rebuild as my backup board. It needed to most traces rebuilt but it will get fixed. In parallel with that project I’ve been using one of my Gameplan Proto boards to build up a custom Arduino based MPU that should allow for emulated original rules as well as expanded rules with new sounds. Once I finalize that I’ll spin up a finalized board for that. Sharpshooter is such a great machine with lots of potential and I think it will be worth upgrading.

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That's a very interesting project! Will you be selling boards once the design is completed?

Yes. That is the plan. Both assembled and in kit form. The source code will be published so it can be used as a starting point for other machines. I’m just coding Sharpshooter but that should work for Sharpshooter II as well as Coney Island with out much change. I’m going to wire up the connector for the cocktail machines but since I sold my Star Trip will have to ask the person that bought it if I can get access for testing. Otherwise that may take mods to initial boards to get perfect.

I’m sticking with all through hole parts and trying to avoid odd chips on their way out. Was considering resistor packs but decided to stick with regular resistors since those made easier to source.

My project doesn’t use or run any Z-80 code or even have the CTC, etc so for anyone that wants to run the original ROMs and code then you’ll want to wait for an Echo Lake board or get your original rebuilt.

Yes, months ago. He has since come back and stated that if the other guy couldn't do it by October, he might make another run.

Just added my first Game Plan machine to my collection, this project Super Nova landed in my hands partially working and needing some TLC. After cleaning the corrosion from the back box to playfield interconnects, replacing defective SCRs and a defective decoder chip in the ball match display and filling in all the cracks in the black paint on the backglass among other things I got the machine back up and running. I’ve resolved the LED flicker issue by adding SCR holding resistors to most of the controlled lamp sockets and among repinning some of the connectors the last electronic issue to work out is the sound board and that is where some questions reside. My soundboard is triggering on all data channels but the sound board is playing mostly beeps and boops, background sound works as well as spinner spark sound but instead of the siren warble on game start along with the spark sound I only get a solid high pitch tone in place of the siren warble. I only get the thunder sound when special is lit and target hit and from what I can tell from some online videos when the pop bumpers light after making Super Nova rollovers the triggered sound should switch from simple beeps to synthesized sounds. My sound switches from a single tone beep on the unlit pop bumpers it then changes to different and separate tone beeps from the 1000 and 5000 point bumpers but no synthesized sounds. I’ve swapped around chips on the sound board with no change so my last thought is to shotgun the disc capacitors in hopes they may be the cause of the simple sound issue. There is very little documentation out there so I’m hoping somebody may have already experienced similar issues with these Game Plan sound boards and have some suggestions. TIA!

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Welcome to the club!
I too, recently brought a Super Nova back to life. Great looking game, and plays well if set up a little steep.
The sound board on this machine is a "dumb" board. All sounds are controlled by the mpu. The board can be easily bench tested. Check out this thread. https://pinside.com/pinball/forum/topic/game-plan-mpu-repair-a-shotgun-guide-w-pix
On these machines it is always a good idea to replace all the green disc capacitors. In particular, there is one on the mpu responsible for timing and if bad, can cause all kinds of strange behavior. It is also discussed in the shotgun guide thread. Good luck!

Do any of the Gameplan machines have caps across the EOS switch to prevent arcing? If not has anyone added them? Just rebuilt the flippers on Sharpshooter with new correct Gameplan flipper coils and new EOS switches. They work great now but did notice arcing on the EOS so was thinking of adding caps like some on others did.

Also some had installed Bally flipper coils and they were way too weak. Now the game can make all the shots.

I’m a buyer for an Mpu board. I left Jim a message but will email as well.

I added a 2.2uf 250v capacitor on each of the EOS switches and it seemed to almost completely eliminate the arcing. It’s much better now. Going to do the same update to my other Sharpshooter. I cable tied each capacitor to the coil to keep it from moving. May still add the .1uf caps for the cabinet flipper switches.

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Built some LED adaptors instead of soldering resistors directly to lamp sockets. Much easier this way. 2A8FDA7F-7758-4FC1-B262-119F6BF4FE3C.jpeg1CE9EF87-4A9C-4A82-A41C-76BC9F9760B9.jpeg

Further troubleshooting my SSU-4 board I recapped all the ceramic caps with no change. Once I determined how to test the sound triggers on the decoder I was able to determine that the simple chime IC was outputting the same note on 3 channels due to a shorted 3904 transistor, the issue with no siren or howl was due to bad tantalum caps and I was able to temporarily replace with electrolytic caps I had on hand and I am now able to hear sound changes between lit and unlit pop bumpers and getting the descending howl on game start. When pops light I get short siren and howl instead of quick warble ascending and descending but it’s a step in the right direction, I’m thinking there might be another transistor not switching sound select properly or a flip flop circuit is not working. Having messed with this board for the past few hours I’m getting very familiar with it.

I’m seeing a similar issue on an SSU-2 with the only issue left is that im getting the same note for multiple triggers. Will have to go back through and check all of them for the chimes then that board will be fixed. When I started with that most sounds we’re missing or wrong and a lot was do to components knocked loose from the board with leads no longer connected.

Ran into a really odd issue on a second SSU-2 when it was just making a odd annoying tone. Lifted on leg of the resistor for the chime section and confirmed it was in that section. All the notes checked out ok. The 74154 tested ok with a chip tester but ended up having some sort of leaking output pin that only partially enabled a tone but not fully. Popped in a new 74154 and that board is solid now.

So one of my two working Gameplan MPU-2 boards was having a couple issues and I finally tracked them down. Sometimes the board wouldn’t recall the saved settings and occasionally it wouldn’t boot. If I reseated the power cable it would come up. Re-pinned the power connector and would still see issues. This is a board that had a lot of poor prior work that I had to tear off and redo.

Isolated it where one it was running if I pushed on the PCB to flex it the board would reboot. Those are some of the worst to find as it’s intermittent. Went back over the area that I was flexing abd reflowed anything even remotely questionable. Then cleared out the solder in the in that area and resoldered using wire wrap wire in the via to ensure a solid connection. That helped and no longer would reboot when flexing the board up by the lamp connector but while better the board still wouldn’t boot every time. I could get it to boot and also reset by pressing around near the crystal. So more work. Did the same fix on the vias in that area as I’ve run into opens with those before. Also removed the crystal that had been reflowed by someone prior and noticed there was too much solder on each pin and one side was for sure making contact with the metal crystal body. Resoldered that with an appropriate amount of solder and added an insulator under the crystal as I’ve seen on some other boards to ensure no contact with the crystal case.

So far so good and the board has immediately booted every time and retains the settings. Both the boards are using and off board battery pack and have 1n5817 blocking diodes on the boards.

There was one pop bumper that was really really weak. Found that someone installed a Gameplan chime coil there instead. Bought the correct coil and now that works perfect too.

While going through it found a couple broken coil stops. I found that the classic Stern (copper colored) fits perfect and is a lot more robust. I just ordered extras so I’ll can replace the remaining broken one and keep spares on hand to replace the rest if needed later.

Have a couple switches to adjust, replace one large filter cap that had too much ripple, then a little more cleanup and these two games are done!

It is going to help having two working machines side by side as I continue work on my alternative MPU so I can compare updates side by side. Also just got in some 7 digit displays that I can use to ensure I can code for and support those for games like Sharpshooter II.

Hey guys, I'm having trouble with the sound on my buddy's sharpshooter--it's not working at all. No hum from the speaker, even with the volume cranked all the way up. I have +5 and +12 at the MSU-2, and I've re-pinned the connectors at the MSU-2 and the MPU, and at the connectors between the head and cabinet.

I'm thinking of trying another speaker, anyone know what the ohm rating is for the speaker?

Any suggestions where to start troubleshooting? Thanks!

A 4 ohm speaker should work fine. Here is a very helpful video regarding troubleshooting the SSU-2.

Many thanks!!! I didn't realize viperrwk put out videos for these repairs too--that video was sooooo helpful! Pretty neat the way these boards work. I'm guessing at this point either a bad volume pot or a problem with one of the amp chips. I replaced the amp chips a while back, but I'll have to double check my work on them.

Also--it appears we have an 8 ohm speaker installed in the game, should I plan on swapping it out for a 4 ohm? It's worked fine with the 8 ohm up till now, but I'll swap it out if it's possibly causing any trouble.

I'll post back when I get a chance to troubleshoot the board and share my results.

Thanks again--that video was extremely helpful!

I rebuilt a board for Lizard, both amp chips were dead.

There are three separate sound sections on the sound board. Each one goes through a resistor which helps mix the signal going to the amp. One sound card I fixed was making bad background noises an unsoldering one leg on each of those resistors one at a time can help isolate which section the noise came from.

With no sounds I’d look the board over for any broken or cracked solder connections. On another board I fixed some parts were knocked loose and a couple leads no longer mad a connection to the board. Look for the obvious stuff first and cracked joints at the headers.

Sounds like you tested for power at the MPU. Did you check for power at the sound board?

If you have access to a scope it should be easy to follow to audio signal to see where the issue is.

Yeah those boards are pretty straight forward, The SSU-4 (which I have worked on recently) has 4 sound generating chips and the resulting sounds depend on the external transistor switching network feeding back into the chip which means that even if one chip goes bad you will still have some sounds from the other. As far as running an 8 ohm speaker the amp chips will have to work a bit harder to drive it. If you have access to an analog amplifying probe used in telephone work you can probe the chip outputs and hear if they are outputting an analog signal to the amplifying section.

Great info everyone, thanks for the replies! I'll keep your suggestions in mind moving forward.

I checked for power at the connector that plugs into the sound board and found correct voltages. I'll get a closer look at the board and check for cracked solder etc. Luckily I have a 10k pot among my parts, so I'll probably replace the old volume pot for good measure whether or not it's the culprit. It appears I replaced and socketed the amp chips too, so I'll have to get another look at my work there. I also found a 4 ohm speaker, so I should have almost all the bases covered parts-wise. Hopefully I'll get the board into my shop soon so I can proceed to troubleshoot. Thanks again!

That's really cool! Wish I had one of those in my toolbox

Thanks again for the suggestions and info, everyone! I plan on getting to work on it in the next couple days hopefully--I'll check back in with my findings.

I use a higher end unit now for work but I used to have one like this and it is affordable and it served me well. https://www.amazon.com/Professional-Generator-Inductive-Amplifier-Adjustable/dp/B08GKR7PRM/ref=sr_1_16