how can i bench test a deck to see if it works or not, without actually installing it in a car, hooking the pos and neg. wires to a 12v battery?

 

ok i hooked the yellow power wire and the red power wire to a 10amp 12v batttery charger, and conected the two black grounds together, hit power and nothing. what could it be?its a jensen cdh900

 

It could be trash.
A battery charger is NOT a power supply, with a charger you NEED a battery there, even if it's small bike/lawn mower batt. But then again you may have just killed the HU.

 

I use a power supply from an old computer. They have a 5v and 12v outputs. Works great.

 

i don't think so, i do it to test headlights all the time...

 

Headlights don't care about ripple or a variable voltage/constant current PS. Get a cheep 12V battery or 12Vdc power supply that will put out 5A at LEAST(only for testing the HU, NOT amps). Or just hook it up to the car battery under hood.

 

well thanks for that little tid bit, i will go do that.

 

Not saying that why it didn't power up, but you need a good clean source before you can say it isn't.
If you want to test big amps down the road a cheap way to do it is a cheap, mid-sides battery and a maintenance charger. A 5A supply isn't really sufficient for a big amps current needs. So if you are going to be doing this down the road you could get a mid-sides battery now and be set.
How do the buttons on that 900 feel. If I remember right they have problems with the button going bad. If one button is sticking closed the unit may never power up.

 

no the buttons are moving all the way, but maybe its stuck inside?

 

Usually you can "feel" a bad button, it just doesn't fell the same as the others. Usually you don't get a noticeable a "click" when you press it. But it is possible that it's shorted or has a low internal resistance when off and still "feel" like it's good. I've seen them (not on a Jenson) feel fine and be 12 ohms or so not pressed.