Tempest firing issue

scottz29

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Donor 2024
Joined
Sep 1, 2006
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Location
Macomb, Michigan
I have a strange firing issue with my Tempest. If you hold the fire button down, the burst of 8 shots will fire, but if you tap the fire button, it won't fire a single shot.

Same goes for starting a game: if you tap the fire button to start, it won't register, but if you hold the fire button, the game will start.

Test screen, same thing. If you tap the fire button, the bit won't register the switch activation. Holding the button for a second or so will eventually trigger the switch, and it flips from 0 to 1.

This is not a dirty leaf switch issue, I have swapped leafs, and the same thing occurs. The button works fine, it only works after you hold it for a second -- this definitely seems like a logic issue on the board. Anyone seen this before, or have an idea what it might be?
 
Actually have to give props to another local Klover that was over helping out getting my Tempest finally running.

This was a weird issue though -- you immediately think it's a bad leaf switch, but you know the button is working in rapid-fire mode, so it's really a board logic issue. Tapping the button (single fire) wasn't working, but holding the button (rapid fire mode) was. We could have confirmed this with the logic probe, but we didn't really need to. We just traced the line back to the first chip it ran through, the LS157, which was a multiplexer. He said they go bad alot, and it was already socketed, so that was an indicator it was fixed before...

I had a similar problem with some buttons not working on my Gorf, but that ended up being a bad .01uf cap *before* it got to the multiplexer, but I remember thinking it was the multiplexer chip...
 
Will work for good coffee...and some classic 1980 Atari color vector goodness!

The impossible is now repaired. I will be waiting at the curb on Tuesday to take delivery...;)

Travelling Tempest Repair Assistant
 
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