Atari self-test switch secrets revealed

maxweb

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I need to replace the coin door self-test switch on my US Tempest upright, and was somewhat confused when it looked like the simple SPST switch indicated in the schematics didn't match the original factory-installed 3-position SPDT on-off-on switch. Furthermore, there seemed to be some conflicting descriptions about flipping the test switch either up or down to active test mode.

After a bit more inspection I see that Atari wired the two outside SPDT switch terminals on my game together. One circuit wire goes to these, and the other wire to the common center terminal. The result is effectively a switch that is normally open in the center "off" position, and closed in either up or down "on" positions. So the switch can be toggled either up or down for test mode, and the center position used for normal game play.

This was probably obvious to folks with working switches, but now I can find an equivalent on-off-on SPDT switch replacement with confidence in knowing it was wired this way to cleverly allow testing in either up or down positions... or maybe to use up existing inventory of on-off-on switches when a simple SPST on-off switch would have sufficed.
 
I noticed that as well. Would have been easier if I had a working switch to start with, haha. The designation for that switch seems to be ON-OFF-(ON). Why would you want a momentary switch downward option for test mode? Would you ever just toggle it on and off without leaving it at least for a while in the on position?
 
I noticed that as well. Would have been easier if I had a working switch to start with, haha. The designation for that switch seems to be ON-OFF-(ON). Why would you want a momentary switch downward option for test mode? Would you ever just toggle it on and off without leaving it at least for a while in the on position?

Probably just threw whatever on there for no particular reason. If they had extras of stuff, that's what would go on.
 
I noticed that as well. Would have been easier if I had a working switch to start with, haha. The designation for that switch seems to be ON-OFF-(ON). Why would you want a momentary switch downward option for test mode? Would you ever just toggle it on and off without leaving it at least for a while in the on position?

Quick way to reset the game.
 
Yeah, what Arcadenut said. It's a quick way to reset the game.

It actually comes in handy, I frequently use it when repairing boards and play testing them in my cabs.
 
The reason for the switch being "maintained" contact in one position and "momentary" in the other direction:

Some games had the software written for momentary pushbutton test switches while other games had software written for maintained contact test switches. This way, Atari only needed to inventory one test switch. Plus if you ever convert an Atari cabinet to JAMMA, you've got a ready to use momentary test switch already there.
 
Some games had the software written for momentary pushbutton test switches while other games had software written for maintained contact test switches. This way, Atari only needed to inventory one test switch. Plus if you ever convert an Atari cabinet to JAMMA, you've got a ready to use momentary test switch already there.


What Atari games use momentary?
 
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