Dimmed Coin Slot Lights After Disconnecting PCB?

[porkins]

In my cabinet, when I disconnect the PCB (Golden Axe) and connect my J-Pac, the coin door lights are very dim, to the point where they seem off from the outside. Inside you can see that they are getting partial power. I still get full power headed to my marquee light. If I reconnect the PCB, they come back up to full power. The coin slot lights are wired directly into the arcade's power supply at -5V and ground. How can I fix this so that I get full power to the lights when I have the J-Pac installed? The only logical explanation of this behaviour is that if the power supply is not pumping power out to the PCB actively, it shuts down power to the -5V. But that seems strange. Help?

[MonMotha]

This is common on switch mode supplies.  They can't run without some minimal load.  Some will run "out of control" and fry themselves, but most will just shut down.  A load on the -5V rail doesn't count towards the minimum limit with most designs.  So yes, this is "normal".

Now, my question is why are you running your coin door lamps off the -5V rail?

[porkins]

I found a post where somebody says that the power supply needs to be removed if there will be no load from the PCB, otherwise it could break. So this opens up a new can of worms. I didn't know I had to do that. So exactly what steps do I need to take? Just pull the plug from the PSU? How do I then power the monitor, marquee light and coin door lights?

[porkins]

Now, my question is why are you running your coin door lamps off the -5V rail?

That's just how it was wired up when I got it. I'll double check it when I get home, but I'm pretty positive they are hooked up to that.

[porkins]

Yes, the coin slot lights are wired up to the PSU's -5V AC and Ground. I also checked the wiring. The 2 main power inputs on the PSU have the power line (from the wall), the monitor power, and the flourescent light power all connected to it. So I am guessing I can just keep the power, flourescent light, and monitor all connected together, but remove these from the PSU so that it doesn't try to run without a load. But then I will get NO light to the coin slots. I have read I can run power from the computer's PSU. But I have heard conflicting things. Would I power off of a hard drive connector (12V is it?) or the floppy connector (5V?) I am guessing I wire the black to the grounding wire of the lights, but then the 5V wire is which? Red? How can I test with my multimeter?