So what did I hose up on the Galaga switching power supply conversion?

jehuie

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So what did I hose up on the Galaga switching power supply conversion?

So the game was playing off the original power supply but I got no sound. I bought an ATX power supply and plugged in the +12 and got sound so all was good with the world.

Then tonight I decided I should go ahead and do it right and install the rest of the switcher lines to the +5 and ground leads. Well, now when I turn it on I can hear the game playing but I'm not getting video.

Also, when I measure the +5 at the board I'm only getting +4.5 or so. Could this account for it not being able to drive the video? If I read the voltage at one of the other connectors I get +5.1 or so.

One thing I did....I'm not sure if this makes a difference but you know how there's a BUNCH of yellow leads that need to be connected to ground? Well, I hooked two yellows to one black wire on the switcher, another two yellows to another black, etc. And I split up the reds to multiple +5 leads on the switcher also. Does that matter?
 
WTF?

ATX power supplies have a 3.3v, 5v, 12v, -5v and -12v outputs... You are not supposed to run them without a sufficient load on the +3.3 and +5v outputs. They could self destruct.

Use an arcade switcher.

Also, the ATX has standardized color codes... Orange = 3.3v, Red = 5v, Yellow = 12v, Black = ground, and I forget the -5 and -12v colors. These color codes won't match the wire colors on your old Galaga cab. Don't hook color to color.
 
I didn't try to match the colors. I hooked the +5 where the +5 should go and the +12 where it should go, etc. And there is a proper load on the +5 since the game is connected. But I wasn't aware of a need to have a load on the 3.3 lead. Is that really true? As long as you connect the green to ground it should be fine. Or at least it always has been when I've done this before.....
 
I don't think you need a load on the 3.3v line - I've run plenty of ATX supplies without it. I think your problem is more related to bad power connectors on the Galaga board itself. Check the 3 pin power connector at the board. Something tells me if you check the voltage at the power supply side of the connector, it'll be 5v, and if you check at the board, it's dropping...

Or, you could have done something silly like disconnect the video connector on the board or at the monitor. That would cause the same symptom :D

Arcade power supplies are adjustable and can be cranked up to compensate for bad connections. Computer supplies are not.

-Ian
 
Arcade power supplies are adjustable and can be cranked up to compensate for bad connections. Computer supplies are not.

Yeah, I thought this would have plenty of oomph and wouldn't need adjustment since they have always worked for me before. But dropping to 4.5v is pretty bad. Hopefully you are right and it's some sort of cable issue or something simple like that. Although it was working fine with the old power supplies +5 lines.
 
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