Dip Switches Not Working

MagicMarc-er

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I'm finally got my Bally/Midway Blue Print working this weekend. The game plays great but I can't seem to change the dip switches. When I go into test mode, it shows that all the dip switches are in position 1 (off), despite that many are actually on. When I flip one of them on the MPU, it doesn't change anything on the screen, still showing off.

Seems a bit weird that both SW1 and SW2 sets of switches are reacting that way. Makes me think the issue is not with the switches but rather somewhere upstream or downstream.

Any ideas?
 
All DIP-switches are connected to the IO/Sound-Chip AY3-8910 @L3.

You can swap it with the chip @N3 and see what happens. ;)
 
All DIP-switches are connected to the IO/Sound-Chip AY3-8910 @L3.

You can swap it with the chip @N3 and see what happens. ;)

There's a good chance you're on to something because I'm also not getting sound yet. I hadn't started working on that problem but, the fact that the dip switches go through the sound chip sounds very suspicious.

I'll swap them tonight and see what happens.
 
Well, I switched L3 and N3 and it didn't impact the dip switches or the lack of sound. I was really hoping that would work. I got some artifacts on the screen when I switched them but that is the only difference. I also cleaned the legs while I had them out but no luck.

Not sure where to go from here.
 
Seems the complete soundsection is dead.

Check the Z80, Clocksignals of Z80 and soundchips, EPROMs @U3 & V3, and RAMs @S3 & T3.

What about Reset of the Z80 (pin 26)? High or low?
 
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