Millipede display and sound issues using the arcadeshop adapter

Waterborn

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Millipede display and sound issues using the arcadeshop adapter

I just picked up a millipede board on a warehouse run today. Came home and tried it in my centipede cab with the arcade shop millipede to centipede adapter. The millipede plays fine, but the colors are really blue and dim and there is no sound. The cab has ZERO issues with the centipede board installed. So the question is, is this an issue with the board or the adapter? Other than putting the millipede board in a millipede cab, any suggestions on trouble shooting?
 
I doubt it's the adapter.. As you pulled this pcb out of a warehouse today, which who knows how long it's been kicking around.. Reseat chips.. No sound usually is the pokey chip. Swap pokeys with your centipede.
 
OK, confirmed both pokey chips are good by putting them in my centipede board. Still dark screen and no sound with the millipede board and no issues as tall with either of my two working centipede boards. Any other suggestions?
 
No audio usually means a bad LM324.

Bad color could be a few things - check video ram, color prom, and associated parts.

Bill
 
Make sure you have +22v and -22v going to the board. If so, check the +15v and -15v regulators on the pcb. Millipede needs both of these voltages for sound and color output.

Brian
 
Make sure you have +22v and -22v going to the board. If so, check the +15v and -15v regulators on the pcb. Millipede needs both of these voltages for sound and color output.

Brian

Stupid question, where do I find and read these voltages? And if the game is running on a switching ps, how does one get the 22V & 15V to the board?
 
Last edited:
Stupid question, where do I find and read these voltages? And if the game is running on a switching ps, how does one get the 22V & 15V to the board?


There are labeled test points on the pcb for each voltage. If you are using a switcher, then that would be the issue. You can use a switcher on Centipede because the 22v doesn't need to be present. The 22v on Centipede runs the high score save circuit. However, on Millipede the 22v runs the audio and is for the color output. If you don't have any 22v or -22v you could try to hook up the +12v to the +15v test point and the -5v from the switcher to the -15v test point. The colors maybe a little dimmer than normal, but you should have sound.

Brian
 
OK, I am a complete moron. First, the game is NOT running on a switching ps. Not sure where that idea came from. I tested all the voltages, both on my working centipede and on the millipede board. All voltages were good on the centipede board, but the +15 on the millipede board was pretty much flatlined. So we are getting somewhere. So since I know that my ps is pushing the +15 as it should, what do I need to check to figure out why the +15 on the millipede board is coming out low?

Thanks for the help by the way. I am pretty new to board trouble shooting, so I am learning quite a bit here.
 
I would look more at the +15v than the -15V since you colors are dark. The +15v regulator is labeled as VR1 and it at the front of the pcb near the edge connectors. If you have 22v going in and no 15v, change that part first. It is a common part. You might be able to find it at Radio Shack.

Brian
 
OK, so I just grabbed the schematic and see where the 22/-22V feeds come into the board, but no 15/-15V. Is this a step down that happens on the pcb?

Basically, yes. The 22v goes in and the 15v comes out and goes to the proper chips. There are two separate regulators one for the +15 and one for the -15.

Brian
 
That would also explain why no audio.
 
Yes, there are labeled 7815 for the 15 and 7915 for the -15. The Centipede will have both of them.

Brian
 
Pulled the +15V regulator off a spare centipede board and now have a brighter screen and sound! Thanks for the help folks! Now the bottom 1/3 of the screen has a blue band on it. Remember seeing this issue somewhere, going to try to look that up.
 
Pulled the +15V regulator off a spare centipede board and now have a brighter screen and sound! Thanks for the help folks! Now the bottom 1/3 of the screen has a blue band on it. Remember seeing this issue somewhere, going to try to look that up.

That's great! Glad to see another Millipede brought back to life! As for the "band", Millipede does have a colored area for the shooter and Centipede does not. Here is how Millipede should look: (see pic).

1181242137379.png


Brian
 
Brian, thanks for the heads up on the band. On my game, the colors are a bit off. Never noticed issues with the Centipede board installed, but the monitor does have some pretty serious burn-in. Going hook up another monitor and play with the controls a bit. Thanks again for all of your help.
 
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