Robotron - switches don't respond

Pac Manz

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Started my Robotron today. Plenty of credits but won't start. Went into test and RAM and ROM are okay, but switch test shows no response for joystick movement or start buttons. Simple fix?
 
I've had the same thing happen to me on my Joust. Turned out that it was a bad solder joint on the interface board header pin. Reflowed solder on the back of widget interface board, all was well.

I also replaced the molex connector and pins to create a better connection and clean the connector on the widget interface board with 3M Scotch Brite.

If the memory has become corrupted during all this, pull the battery for a minute or two on the main MPU board and that should clear it. Sometimes a shorted or bad widget board can cause other strange "won't start" issues like this.

Good luck..
 
No response on any of the buttons is usually caused by a loss of ground. Verify that all of your grounds are good. If you are using a switching power supply, verify that you even have a ground present.

If you only have certain buttons that do not respond, test them directly on the widget by individually grounding them. The ones that do not respond will usually be caused by a bad 4049 on the widget.
 
Check the start switches. They will gunk up over time. To clean them use a drop of rubbing alcohol on each side of a white business card (or index card), slide the card between the contacts and move it back and forth until it is clean.

Do not use sandpaper. Even the 1000 grit wet dry sandpaper. The contacts have a very thin gold coating and sandpaper will take it off. At that point, the switches will work for a while, but eventually they will pit from the arcing and then they will become unreliable and will need to be replaced.

ken
 
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