Powering stero with Computer PSU

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December 30, 2009 at 12:12:17
Specs: Windows XP
I have a 250 watt car stereo amp to power my home stereo. I am powering the amp with an 800 watt computer PSU. I have it connected correctly (I believe). When I plug in the PSU the amp comes on, but when I turn on the stereo the PSU shuts off. What could be causing this?

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#1
December 30, 2009 at 14:14:10
Where does the stereo get it's power?

Goin' Fishin' (Some day)


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#2
December 30, 2009 at 14:46:25
My guess the 12v rail is overloaded. The amp uses only 12 volts while the ps supplies substantial wattage at 3.3 and 5 volts. Check your labels.

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#3
December 30, 2009 at 15:13:44
Stereo gets its power from the wall...
What labels would tell me? And what should I be looking for? Please keep in mind, I am an idiot in this arena.

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#4
December 30, 2009 at 15:36:48
A 250Watt amplifier @ 12V draws 21amps.

If your powersupply has multiple +12V rails they are commonly limited to 20amps each. Your car amp would overload the powersupply as soon as a load is applied . eg: when the Stereo is turned on and calls up the amplifier. It would not matter if you had a 600W or 1000W computer PSU if the +12V rail connected to the stereo amp can only deliver 20amps or less

Check the label on the side of the powersupply. It will list the amp ratings for each voltage rail..

Goin' Fishin' (Some day)


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#5
December 30, 2009 at 18:32:39
My guess is it's a grounding problem because the amp is powered by the PSU and the stereo by the wall socket. The psu acts as an isolation transformer so when the audio signal is connected to the amp it sees no ground. The stereo and amp need a common ground after the PSU and not before (in the circuit).

Of course I could be completely wrong so I wouldn't make any suggestions because I don't want to be blamed if you blow something up.

Ubuntu Cheeta, Ubuntu !


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#6
December 31, 2009 at 08:31:11
Looks like you are right. There seem to be 4-12 volt rails which put out 20 amps each. How do I fix this?? Can 2 rails be combined? If that were done would the resulting 40 amps blow the amplifier? Should I just set fire to the whole thing and start over?

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#7
December 31, 2009 at 09:04:21
Try a single +12v rail psu

No

No

Yes

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#8
December 31, 2009 at 09:37:01
HA!!!! Thanks man.

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