Alien Poker drop target resetting problem

My Alien Poker has received a lot of repair attention lately. It even has received a new Rottendog MPU/Driver board combo. Important to note, the drop targets, though previously a bit sticky and inconsistent, generally worked OK when this board was installed around a month ago.

To fix the sticky inconsistency of the drop targets, they have been rebuilt with new springs, horseshoes, individual PCBs, and a few other parts. They now mostly work great. So what’s the problem?

As you (experienced pinball player that you are) know, when you hit the targets from right to left (10, J, Q, K, A), the targets should stay down. They do. Further, when you hit a target out of order (e.g., Q before 10 and J are completed), it’s supposed to pop back up. It does, except…

I can consistently get the targets to screw up by hitting two targets at once. For example, if no targets are down and I hit the Q and K, the Q will go down and pop back up but the K has a really good chance of (incorrectly) staying down. No other condition other than hitting two targets at once seems to cause any problems. But, this 2-target thing is a relatively big and consistent problem.

Because the board is new and definitely allowed the drops to work correctly in the past, I’m ruling it out. The new PCBs ( are certainly suspect here, but I’m at a loss to dig in and fix this problem beyond this general idea.

Any suggestions you provide will be appreciated.


I’m assuming you followed the specific instructions for alien poker?

I’d ask siegecraft, he seems pretty helpful.

I have no experience with these games that use this tech.

Here’s the solution from my tech friend, in case anyone runs into the same problem.

Hans at Siegecraft drew the AP schematic for his replacement PCBs from the official Williams schematic. His original drawing had the boards using the “momentary” pads. This worked but was missing the second drop when two were hit at once. He suggested moving the wiring to the “full down” pads, which I did but, in hindsight, did incorrectly. I simply moved the wires from the outer connections to the inner ones, not noticing that the row and column labels were, in fact, swapped on the inner pads. This made the diodes appear to be in backwards. Eventually, I swapped the multimeter leads. Then, no connection became full connection so it was apparent the diodes were not conducting. That led me to spot the difference on the PCB labels and swapping the row and column wires got things going! Photos of my Alien Poker proved that it was also using the 'full down" pads so i knew that should be correct. I’m going to let Hans know that his AP schematic is wrong so he can put a corrected version on the web site.

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