Computer PSU (AC) to Power Opus

**Jcarere** · 11-17-2005, 06:48 PM

I have an old 400 watt power supply that has a 15amp 12volt rail. I cut the power wires off the molex connector and used the computer powersupply to power the opus by shorting the green and ground wire on the psu to turn it on without a motherboard.

My question is the opus runs all my accessories and screen running off the computer psu, but the ac power supply has small gauge wires. I was wondering why the wire gauge is so small. 18gauge i believe. Would connecting the two 12volt line is parallell be safer for powering the opus. This is for testing purposes in the house rather than the car.

**Wiredwrx** · 11-17-2005, 07:12 PM

Originally Posted by Jcarere

I have an old 400 watt power supply that has a 15amp 12volt rail. I cut the power wires off the molex connector and used the computer powersupply to power the opus by shorting the green and ground wire on the psu to turn it on without a motherboard.

My question is the opus runs all my accessories and screen running off the computer psu, but the ac power supply has small gauge wires. I was wondering why the wire gauge is so small. 18gauge i believe. Would connecting the two 12volt line is parallell be safer for powering the opus. This is for testing purposes in the house rather than the car.

Using several of the 12 volts wires is perfectly acceptable. The reason the wire can be so "thin" is because of the length of the run, it is just several inches.

Hopefully this won't turn into a voltage/amperage/wire length discussion.

Michael

**Jcarere** · 11-17-2005, 07:15 PM

k thanks for the reply.
To test the amperage draw of the opus do u just connect the positive from the computer power supply to the postive on a multimeter then the ground to the positive on the opus?

**Wiredwrx** · 11-17-2005, 07:27 PM

Originally Posted by Jcarere

k thanks for the reply.
To test the amperage draw of the opus do u just connect the positive from the computer power supply to the postive on a multimeter then the ground to the positive on the opus?

Yes, but make sure that the meter can handle about 20 amps of current. Many/Most meters can not handle that amperage.

Michael

**kbyrd** · 11-17-2005, 07:38 PM

Originally Posted by Jcarere

I have an old 400 watt power supply that has a 15amp 12volt rail. I cut the power wires off the molex connector and used the computer powersupply to power the opus by shorting the green and ground wire on the psu to turn it on without a motherboard.

So you're 400W can provide 15*12 = 180W to the opus. Which opus is it? If it's the 150W version, then it'll provide 150W max, it's probably 90% efficient in which case it'll need about 165-170W input to provide 150W output. I don't see a problem.

**Wiredwrx** · 11-17-2005, 07:44 PM

Originally Posted by kbyrd

So you're 400W can provide 15*12 = 180W to the opus. Which opus is it? If it's the 150W version, then it'll provide 150W max, it's probably 90% efficient in which case it'll need about 165-170W input to provide 150W output. I don't see a problem.

Or to make it simpler, the Opus probably needs about 165watts (for efficiency reason)/12 volts=13.75 amps. Since the PS can supply 15 (hopefully constant) he should be fine.

Michael