Hello from Burnsville, MN

dennyfmn

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I have a 1981 Atari arcade Centipede that I'm trying to put back in service. I bought it from an arcade in the late '80s and played it for quite a few years. It finally died and it has been mothballed for about 25 years. I'm working on the +5V supply now. I have a full set of manuals and schematics. If anyone nearby has an EPROM reader/burner or an Atari CAT box, I'd be very pleased to contact them. The game partially plays if I substitute an external +5V supply, but several entities like the mushrooms and the bullets don't show on the screen. The background color is not black. The self-test mode doesn't work right either. I'll post a more complete message in the Centipede forum. I'll appreciate any help! Thanks!!!
 
Start with the power supply.

That means the AR board and the power brick in the bottom. You also need to check your AC Ripple on the 5 vdc line - it has to be less than 0.5 vac.

Check all your fuses - ohm between the fuse barrel and the connector, look for high resistance. Those fuse blocks have a reputation.

Check the 3055 on the AR board - if you have low 5VDC, that's probably your culprit.

Clean your edge connector with a fiberglass pen and give it a light coat of DeOxit.

Let's get your power stabilized before we go off going into the boards. Low voltage will cause many problems which can be corrected just by fixing the voltage.

I have a Centipede Cabaret, so if you need a check of something, let me know.
 
Thanks for the info! I have LM305s on order; they should be showing up tomorrow. The 2N3055 seems ok on the bench, but if the LM205 doesn't fix the supply, that's next. I have cleaned the edge connectors (carefully) with a fiberglass pen. With the external +5V in place, all the other voltages on the game board look good; I guess this implies all the fuses are OK, but I will check them with an ohmmeter. The AC ripple on the +10.3V Unregulated seems OK, implying the Big Blue cap is OK. I'll check this further when I get the +5V fixed.

I totally concur. Get all the voltages right before tackling logic problems. Thanks!
 
Ok, the +5V is now fixed, the 2N3055 did the trick. I first changed the LM305 but that was not it. I'll start up a thread on the main forum topic to continue with troubleshooting. The game plays, but several things are missing from the display. I did find fuse F2 was open and replaced it with no changes to the symptoms. Thanks for your help...
 
Great! Thanks!

I'm working on a post for the main forum...
 
Centipede is one of my many favorite games. I have one in my collection and it plays so so nice.

Welcome to the forum look forward to seeing your posts.
 
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