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Hooking a car headunit to a computer psu for testing..........

S

stevens

Senior member
I would like to make sure my new headunit works before i install it into my car. I thought that it would be as simple as hooking up the 12v line to the 12v on the hu and then grounding it but when i do that nothing happens. I am thinking that is because the psu is atx and not at. Is there anyway to trick the psu into giving power to the 12v line? Do i need to hook anything else up to get it to work? thanks
 
Doesn't a headunit use AC power while PSUs give out DC? Or am I just wrong?

In any case it shouldn't be that hard to wire up, I see street performers do it all the time.
 
it's easy. Only a couple steps to do this:

1) twist red and yellow wires on HU together. Attach them to +12v on your PSU
2) Ground out black wire or connect to -12v.

that's it. You should have power. Be warned, however, that this is unfused...so in the event that you happen to get struck by lightning, you may blow the fuse on the back of your HU.

-=bmacd=-
 
Originally posted by: bmacd
it's easy. Only a couple steps to do this:

1) twist red and yellow wires on HU together. Attach them to +12v on your PSU
2) Ground out black wire or connect to -12v.

that's it. You should have power. Be warned, however, that this is unfused...so in the event that you happen to get struck by lightning, you may blow the fuse on the back of your HU.

-=bmacd=-
Click to expand...

You need to short the green wire to GND to get the PS to power up. Then it may not work as it won't "sense" a load, but that depends on the PS.
 
Originally posted by: amnesiac 2.0
Doesn't a headunit use AC power while PSUs give out DC? Or am I just wrong?

In any case it shouldn't be that hard to wire up, I see street performers do it all the time.
Click to expand...

You're just wrong 🙂
 
Originally posted by: SuperSix
Originally posted by: bmacd
it's easy. Only a couple steps to do this:

1) twist red and yellow wires on HU together. Attach them to +12v on your PSU
2) Ground out black wire or connect to -12v.

that's it. You should have power. Be warned, however, that this is unfused...so in the event that you happen to get struck by lightning, you may blow the fuse on the back of your HU.

-=bmacd=-
Click to expand...

You need to short the green wire to GND to get the PS to power up. Then it may not work as it won't "sense" a load, but that depends on the PS.
Click to expand...

the last thing i want to do is disagree with a leet, but from my three years installing car stereo equipment, i think you're wrong. The only required wires to power a HU are the two power wires (+12v and +12v ignition) and ground (generally black, seldomly green). Speaker wires aren't necessary to power the unit.

-=bmacd=-
 
Originally posted by: Colt45
Got a car battery charger? you'd be better off using that if you have one..
Click to expand...

WORST mistake of your life. Don't do this.

-=bmacd=-

edit: if you really feel the need to do this and for whatever reason can't get the right power load from your computer PSU, goto Radioshack and get a regulated power supply some pics

 
Originally posted by: bmacd
Originally posted by: SuperSix
Originally posted by: bmacd
it's easy. Only a couple steps to do this:

1) twist red and yellow wires on HU together. Attach them to +12v on your PSU
2) Ground out black wire or connect to -12v.

that's it. You should have power. Be warned, however, that this is unfused...so in the event that you happen to get struck by lightning, you may blow the fuse on the back of your HU.

-=bmacd=-
Click to expand...

You need to short the green wire to GND to get the PS to power up. Then it may not work as it won't "sense" a load, but that depends on the PS.
Click to expand...

the last thing i want to do is disagree with a leet, but from my three years installing car stereo equipment, i think you're wrong. The only required wires to power a HU are the two power wires (+12v and +12v ignition) and ground (generally black, seldomly green). Speaker wires aren't necessary to power the unit.

-=bmacd=-
Click to expand...

Where did he mention speaker wires? the green wire and ground he is talking about is on the computer PSU.
 
Originally posted by: bmacd
Originally posted by: Colt45
Got a car battery charger? you'd be better off using that if you have one..
Click to expand...

WORST mistake of your life. Don't do this.

-=bmacd=-
Click to expand...

I do it all the time.. no problems ever. i usually put a car battery in paralell with it though, if im running an amp..

12VDC = 12VDC.. wheres the problem?
 
bmacd...the power supply won't give any juice unless the green is shorted. That's just the way computer PSU's are.
 
edit: bunker cleared things up. sorry for the confusion folks

-=bmacd=-

AND: you didn't tell him to use a battery in parallel with the charger. If he were to run the charger straight to the HU, he'd run too many amps to the HU and surely blow a fuse.
 
Ok well i have done everything right and got the psu to supply power but my head unit wont turn on. I have the red and yellow wires connected and hooked to 12v line in the psu. The ground wires are connectted and the psu is giving power. Is my head unit dead?????? I really hope it isnt but it is one that i got on ebay that was advertised as used but then when it came it was a refurb. Is there anything i have to get the hu to power up the first time?
 
don't assume that the HU is dead. Go to RadioShack and pick up a Regulated Power Supply. There are only three wires to hook up there (and no semi-complicated grounding out of PSU's).

Otherwise, you can get a multi-meter and make sure that there is positive current flowing through the PSU by hooking the red lead (+) of the multi-meter to the +12v connection of your PSU and the black lead (-) of the mult-meter to the ground that you were using.

For the sake of ease, get the regulated power supply. You can get away with the lowest amperage model seeing as you won't be running a heavy load on the RPS.

-=bmacd=-
 
Why are you testing a "new headunit"?
You will need the car harness adapter no matter what, so just use that b4 bolting everything in if you *have* to test it first.
 
he bought the HU off ebay. Before he goes full force installing it into his car, he wants to verify that it works before he puts the time into installing it.

Correct me if i'm wrong stevens

-=bmacd=-
 
i'm not sure if this will help.
but i believe there's another line.

you need

+ 12v
ground
power trigger.

i think the last one is the key.

it's been a while since i last did audio install for a car.
but if i recall correctly... you need those three things in order to power up.
 
he bought the HU off ebay. Before he goes full force installing it into his car, he wants to verify that it works before he puts the time into installing it.
Click to expand...


You are exactley right. And i wanted to test out the stereo because i am finding it very dificult to install. Not because i dont know how just because it is really hard taking the panel out of of my volvo 740 station wagon and then finding the factory amp to uninstall that. I was bored tonight and thought that i would try and see i fmy hu actually worked before i installed it. GOOD NEWS!!!!!! I tryed a different psu that was more powerfull and i was able to get the hu to turn on. So it works and the display looks really cool. Now i kinda have a different qustion. Could anyone that if familiar with the volvo 740 tell me what the easiest way to locate and get the factory amp out is? Thanks
 
Originally posted by: hoihtah
i'm not sure if this will help.
but i believe there's another line.

you need

+ 12v
ground
power trigger.

i think the last one is the key.

it's been a while since i last did audio install for a car.
but if i recall correctly... you need those three things in order to power up.
Click to expand...

Originally posted by: bmacd
The only required wires to power a HU are the two power wires (+12v and +12v ignition) and ground (generally black, seldomly green)
Click to expand...

key=ignition

-=bmacd=-
 
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