I am not getting +5 volts to my gottlieb system 1 Mpu board.
My power supply is producing +5 -12 fine but when I plug my Mpu in I only get -12
My first thought was a bad C16 but I changed that out with a known good one but I still get no voltage
I put a jumper directly from +5 and ground to the Mpu and still no volts. The jumper has the +5 but when I attactch it to the boards edge connector I get nothing.so that rules out a bad pin or bad trace. Any help would be appreciated
A few things to check:
1) Repin the connector. Connector pins in system 1 games aren't great and are usually worn and tarnished.
2) Clean the edge connector pads with a pink rubber eraser. There is usually a layer of grime/tarnish on them. Some people will suggest sanding, but I always recommend against that since that just thins the material, which is already quite thin.
3) Do a continuity test with a multimeter from the pad to the 5v test point
4) It's possible that the header pins on the power supply have cracked solder joints. If you have to take apart the power supply anyway, it's usually best to replace the header pins.
3) Do a continuity test with a multimeter from the pad to the 5v test point
I’m not sure where the 5volt test point is.. but this is what I had dined:
I had jumpered from the 5volt pin on the power supply to the 5 volt pad.
The alagator jumper showed 5 volts but the pad didn’t. ( which makes no sense to me)
In other words I got 5volts on the jumper but when I attached it to the edge connector I got no voltage.
Then I tinned over the pad and I still got no volts FROM THE PAD!
Well sometimes you just have to sit back and look things over before you you do too much!
Turns out I had defeated the slam switch a while back and had this board on a shelf. The wire I soldered on the back of the board in a U shape had bent down and shorted to one of the registers next to it and I lost my +5volts.. the Board is now fully functioning.....
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