Defender Arcade - ship reverses with joystick

fmetz374

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I have a strange intermittent issue with my Defender Arcade Control panel. When I pull down on the up/down joystick, the ship also reverses direction as it goes down. Consequently any time I want the ship to go down, it also reverses. The Reverse button also switches direction on the ship so I'm thinking the joystick is somehow wired into the reverse button? This happens intermittently and I can't figure out what triggers this. I'm looking for a wiring diagram on the switches/buttons for the control panel. Does anyone have any suggestions? Is this a possible known issue with Defender Arcade machines?
 
Well, the first thing to do is check the wiring to the reverse button. It should have an Orange/Violet wire (Reverse) and an Orange/Black wire (Ground). Down on the Joystick will have an Orange/Grey wire (Down) and an Orange/Black wire (Ground). Check both to make sure there are no exposed wire from someone hacking them up. If either has exposed wire contacting the other, that would do it.

Next, check the spacing on the Reverse button's leaf switch blades. If they are too close, perhaps the vibration from moving the joystick down could cause it to actuate.

Then verify that no wires are stretched too close to the Reverse leaf switch and possibly pushing them closed during gameplay.

The final step is to go to the interface board (widget) in the back where your two orange-wired connectors are plugged in. Make sure they are connected - and wired - like this:

DefenderInterfaceConnectors.png


Once you've done all that, then the next step is to troubleshoot your interface board. Perhaps you have a bad PIA or something there. But check the easy stuff first. If it all checks out, then we can get into more detail on what to do next...
 
Thanks for the detailed technical reply. I'm always impressed by the wealth of knowledge in this forum. I tried all of the simple/easy things to troubleshoot and none of those seemed to resolve the intermittent reverse issue.

I believe I have fixed the issue though. I pulled out the interface pcb and re-flowed the solder on the back side of each pin that connects to the gray ribbon cable. It may have been a cold solder joint on the pins. So far the issue has not resurfaced after hitting each solder point on the ribbon cable pins.

I'll keep my fingers crossed.

Thanks again for the support!
 
I was going to say, yes - pull the widget board. If you notice the wiring diagram, pins 8 & 7 are Down and Reverse. Something may have been bridging the two connectors causing a short between pins 8 & 7. Just removing the widget board could have cleared it up. Sometimes just a quick dusting of the boards is all it takes! Congrats on getting it up and running again!
 
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