TL;DR; Always check fuses first!

We love to play our Data East TMNT Pinball, but unfortunately the ball got lost more and more often, due to weak flippers. The flippers did hold up, but one could easily push the down, and so did the ball. What’s the problem a big mystery! First, we thought it’s something mechanical and did rebuild the flippers - both side. For that we used the DA Flipper Rebuild kid from Pinball Center(?). The flippers got more precise, but kept on being weak. It had to be something electronic.

So we started to learn about Solid State Flippers, were the control unit is located and Diodes. We followed this great guide from Flipperwinkel, a lots of insights, but couldn’t spot any problem. So we started measuring volts and current. It turned out that one of the fuses was broken. Important part about this is, that the flipper controller has four fuses. One for each flipper to activate, and two to hold any flipper. Which means, even when one hold fuse is broken, the other still holds up. But only half the current, so the flippers results in being weak. We replaced the broken fuse, and the flipper work as strong as never before… check!

While doing the research, we found a good resource for Pinball hacks/repairs: http://pinballrehab.com/articles/solid-state-repair/tutorials/menu/page:2/