Row of 0's in Centipede

mchay

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I'm experiencing some problems with my Centipede machine, after booting it up today. By the Score there is a vertical row of 0's when playing, and random numbers when on the screen showed in the attached picture.

I tried removing the socketed IC's and reinserting them and checking the voltages om the board, which checked out nicely.

Any ideas as of what to try next? The Centipede reacts on the 0's by not going through them when playing, and is quite irritating.
 

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Put the machine in test mode and see if it gives any ROM errors.

I'll try that. Don't know why I didn't think of that. Maybe because last time i used the test mode, it just made a continous beeping noise, without showing anything on the monitor - but played fine.
 
Count the beeps and that will tell you which ROM or RAM is bad.

RJ
 
i had the same problem and it kept triggering the coin counter. i reseated and cleaned the edge connector and it fixed it.
 
Well, cleaning the edge connectors didn't have any effect. Just ordered an eprom reader, to check out the roms on the PCB. Does anyone know which ROM the test mode part of the game is stored on?
 
Hmm, what is the best way to resolve this problem - if it's a faulty RAM?

In test mode, it just beeps continously and displays H's on half the screen and then the vertical line of 0's. Don't think I mentioned that before.
 
Okay, I'll let it beep on and see if it ends later today.

I'm just curious. The manual states up to 10 beeps, to determine where the faulty RAM is located. This beeps a lot more times, haven't really heard the end of it the times I had test mode enabled.
 
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Have you tried replacing the 6502 cpu with a known-good one? Also try swapping out the Pokey - probably not the problem but you never know. The cpu might think it's a PF RAM problem, but it might be more than that.

Also if you're getting more than 10 beeps then don't bother counting them. :)
 
Haven't tried replacing anything yet - will have to buy anything that needs replacing - so I'm just searching for the possible causes, before ordering parts.
 
But what do I do from here? :)

If you've covered all the usual suspects, ie. checked all voltages, clean / replace connectors, re-seat chips, try known-working chips, inspect board for obvious defects, etc, etc and you're still having problems, then I can take a look at it. Bench-testing is free. For repairs I charge a flat fee and it includes fixing everything that's wrong with the board. I have a device that scans through the memory and finds anything wrong with the program and playfield RAMs, and program ROMs. You're board will be 100% when I'm done. PM me offline if interested.
 
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