Installing switching power in ms pac

Seifer13

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Hey was wondering if anyone could tell me the best way to install a switching power supply in a Ms Pac cab. Right now it is rigged up with all the original wiring but is giving off too much voltage. I am going to wire it up Jamma if I can get it installed
 
Ms Pac normally converts the AC voltage from +7 down to +5 on the PCB itself. I'd recommend turning the knob on your switching power supply up so the output voltage is closer to 6 volts DC. Someone correct me if I'm wrong, but I have read that if your input voltage from the switcher is set to exact or near 5, it can cause reset problems if the +5 ever drops below 5 since the PCB expects 7v input.

Bob Roberts sells an adapter kit for $17 that simplifies the connection to your switching power supply if you aren't comfortable going directly into the input lines on your harness:
http://arcadecontrols.com/BBBB/pacpower.html
 
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The reason the voltage drops is because its running through rectifier diodes and causes a slight drop. Simply adjust the +5 up measuring on the board after the diodes. C3 is a good place to check it.
 
Right now it does not have a a switching power supply hooked up. It is just running straight from the transformer but its giving to much power and burning up my boards. I need to know how to install the power supply
 
Right now it does not have a a switching power supply hooked up. It is just running straight from the transformer but its giving to much power and burning up my boards. I need to know how to install the power supply

It's pretty straight forward. There are two methods to do it...
The first:
You splice your wiring harness and run the 5v output from the switcher to the 7 volt lines on your harness....do the same for the 12v on your harness from the switcher.

this site shows pinouts and if you scroll down to the "DC Power" section, it will tell you where to attach the power from your switching power supply:
http://www.mikesarcade.com/cgi-bin/spies.cgi?action=url&type=pinout&page=Pac.html

If this seems too overwhelming for you, I have an adapter kit from Bob Roberts that is already assembled. It plugs into your current PCB and the harness plugs into it. There are leads that come off of it that plug into your switching power supply without having to hack into your harness. I'll let it go for $20 shipped if you are interested, but again...I'd recommend the easy route and just cut the wires on your harness, plug it into your switcher according to the pinouts on the site I referenced and you should be good.
 
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The transformer used for your monitor should have taps for 120....connect from 0 and 120 on the transformer to your switcher.

You can also splice into the lines running to your light ballast and run those to your switcher.
 
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