I want to call your attention to a daughterboard I developed to reduce or eliminate system resets related to the 5 Volt power supply in WPC era machines. I designed this new solution out of frustration with recurring resets in my Party Zone machine. In designing the daughterboard I took a holistic view of the WPC power supply designs, the loading of the supplies, the many possible weaknesses that become triggers of resets, and my knowledge of modern semiconductor products. From this analysis and through experimentation with several prototypes I determined I could safely move the power load of the MPU from the 5 volt supply to the 12 volt supply via a daughterboard that genterates and delivers a separate, stable, 5 volt supply to the MPU.
I like my daughterboard design because:
(1) It is a plug-and-play installation and the installation is completely reversible. No soldering and no wire or trace cutting is required to install the daughterboard so it can be removed from your machine as quickly as it can be installed.
(2) The watchdog circuit remains fully functional monitoring the power on the MPU board where the most sensitive chips (processor, ASIC, game roms) are located. But off-MPU hiccups no longer cascade into the MPU to trigger watchdog resets.
(3) The resultant redistribution of power loads is an improved balance across the available supplies compared to the factory design.
You can find detailed technical descriptions of my daughterboard on my KAHR.US Circuits website at http://www.kahr.us . You can buy one through my website or through eBay (note - purchases outside the United States can only use eBay).
This new solution is not intended to substitute for maintaining the power supply circuitry in WPC systems, but it does eliminate the need to fret over every hundredth of a volt.
Thanks for taking the time to take a look.