LyonsArcade
Well-known member
Hello;
I'm working on a Defender for a guy, and i'm getting a rug pattern at boot up. He had somebody else work on it, and one of the decoder roms had a broken leg, and a cap had been broken next to the other decoder rom, so I repaired that stuff. I checked all my roms, everything seems good, sockets all meter out good, so I was looking around on here, lots of suggestions on checking the power supply.
This cabinet has a switching power supply installed, a pretty hefty one that isn't adjustable, it's the big silverbox kind, and looks like a kit somebody ordered from somewhere, because it has pinned connectors for the (three?) boards that get power from it.
Here's the strange part, when I check the voltages at the cpu's pins (which have been replaced) I get all the correct voltages.
Measuring at the RAM, though, I get craaaaaazy voltages. For example, using the battery holder as the "Negative" post, I get -1.4v at pin 1, 5.1v at pin 8, 5.1v at pin9, and nothing (shorted to ground I suppose?) at pin 16.
Uhh.... help?!
I'm working on a Defender for a guy, and i'm getting a rug pattern at boot up. He had somebody else work on it, and one of the decoder roms had a broken leg, and a cap had been broken next to the other decoder rom, so I repaired that stuff. I checked all my roms, everything seems good, sockets all meter out good, so I was looking around on here, lots of suggestions on checking the power supply.
This cabinet has a switching power supply installed, a pretty hefty one that isn't adjustable, it's the big silverbox kind, and looks like a kit somebody ordered from somewhere, because it has pinned connectors for the (three?) boards that get power from it.
Here's the strange part, when I check the voltages at the cpu's pins (which have been replaced) I get all the correct voltages.
Measuring at the RAM, though, I get craaaaaazy voltages. For example, using the battery holder as the "Negative" post, I get -1.4v at pin 1, 5.1v at pin 8, 5.1v at pin9, and nothing (shorted to ground I suppose?) at pin 16.
Uhh.... help?!
