I recently bought a space invaders in ok condition. Needed to replace the J3 connector (in the backbox) as there were issues starting a game (after transport), but I knew about this before, when I bought it. It seems the gentleman I bought it from had a friend get it running. His friend was , how do I say politely, a butcher, haha. In my excitement to buy this machine and get it home, I neglected to give it a huge look over. In any case, the issue that I am having now is that the knocker is not functioning (coil tests good), it won't register a free game credit, special not working, extra ball wont register and it appears dip switches are not working. I notice that the MPU is a Stern as well. The transformer assembly board in the cabinet looks kinda rough as well. My question to you is should I start with replacing all the connectors on the transformer assembly board and go from there or start with the MPU? Im leaning toward a connector issue but its still early on. I added some pics of both boards for your consideration. Thanks!

mpu (resized).jpg

rectifier (resized).jpg

Thanks for the sound advice. Do you figure that would solve all the issues? I hear this machine has a major issue with connectors and I can see evidence of quick connector repairs all over the place, including liberal usage of hot glue to permanently affix the connectors..

Yes. It appears that the dip switches wont release from some sort of default setting.

The battery pack, yes, with really long leads so it sits on the ledge.

Dip switches wont respond at all, regardless of settings. For example, to change it from 3 balls to 5 balls, score for replay, match settings, sounds, etc. It is like they are permanently locked. Game plays , but you cant get an extra ball or free game or match.

Thank you, I appreciate it. Im going to try right now and get back to you, haha

I kind of feel like an idiot....Mistook off position for on. Your solution worked and I have all functions now. Thank you very much, I owe you one!