Pacman switcher, 5 volts or higher?

Neverendz

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Hey all,

I'm putting a switcher kit from Arcadeshop in a Pac. Should I keep the 5 volts at 5.2 or run it as close as I can get to 7 volts?

Thanks in advance!

, Bill
 
The 7v is AC. It then goes through 2 diodes on the PCB to rectify it to DC. Some people jumper across the diodes and make them non-existent and set their power supply to about 5v. Others leave the diodes alone and jack up the voltage on their switcher. Either way, you want 5v at the chips. Best to use a meter on the +5v and ground of a chip on the board and adjust your supply accordingly to have 5v-5.1 at the chips.
 
Someone let me know if I'm wrong here, but if you crank your switcher right up, does that not also increase the 12V as well? There is a link somewhere how to do it with 5V, I did it with mine. I will post it if I I can find it.
 
Someone let me know if I'm wrong here, but if you crank your switcher right up, does that not also increase the 12V as well? There is a link somewhere how to do it with 5V, I did it with mine. I will post it if I I can find it.

Yes, you are correct. If you turn the adjustment pot it will increase the voltage on the +5v and +12v. But, in the case of Ms. Pac it doesn't matter. The original Ms. Pac power setup uses the 7v AC from the transformer to generate the +5v for all the chips. The schematic shows it also uses part of the 12v AC. More importantly, the 12v AC from the transformer is used to generate +16v DC to power the LM1877 sound amp. But, if your using a switcher, the +12v DC is used instead of the +12v AC and even if you increase the voltage, the LM1877 has a voltage range of +6v - +24v, so you'll never get to a point where the increased +12v will do any harm. As long as the chips are being supplied with +5v the game is happy.
 
Thanks so much! That information was very insightful.

Exactly what I needed to know.

Thanks again!

, Bill
 
I know, but if you don't want to hack up the wiring harness...

No need, simply tie it all in at the fuse blocks. Just be sure to remove the fuses if the transformer is left in the game. Trust me man, done it and it works. The best part is nothing is modified that cant be switched back in a couple minutes.
 
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