Data East Simpsons power issue

shess

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My DE Simpsons had been working fine and I hadn't touched it in a couple months. When I powered it up, I noticed the PIA light was stuck on and it never booted up. I kept trying to power it up and even reseated the connections on the transformer but it never came up. One time after leaving it on for a while to see what would happen I noticed the sound had some distortion in it and then one of the coils heated up to the point of smoking. I disconnected the PPB board to continue testing. I eventually hooked up my multimeter to the +5V and GND tabs on the mainboard and watched as the voltage slowly rise from 2V and when it got to about 4.5V the machine booted up finally. Now that I've booted it up a few times it doesn't seem to have any issues except for that smoked coil.

I'm thinking it's on the power supply, but I'm not sure which parts need to get replaced. The electrolytic caps look recent except for the 18000uf filter cap. Also the 12 pin molex has a burned pin on it. Where should I look at or should I just replace all those standard parts (bridge rectifier, filter cap, molex conn, etc) ?
 
can't tell you from memory, but just take a look at the schematics that are involved on the powerboard with the +5v voltage and measure/replace them..
 
The problem is, I can't reproduce it now. I think it's a capacitor issue and maybe after staying on long enough the dried out caps are hobbling along again. All of them look like they've been replaced except for the 18000uf filter cap so I'm going to try that one and see how it holds up. Unfortunately I'd probably have to leave it off for another couple months to see if the problem comes back.
 
Chances of the filter cap being an issue are slim to none. You've got a slow crawl to near 5v? My first though would be to look for cold solder joints, and reflow the headers.
 
The problem now is that I don't have the slow crawl anymore, it works every time. Although I did remove the power board and put it back so I did have to reseat the power connectors. The filter cap is already on order so while I'm replacing it I'll reflow all the connectors. This will teach me to play my games more often.
 
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