Servo help

Im trying to control a servo (JR NES-4721) with my arduino, and Im having trouble getting it to work. Ive checked the waveforms with an oscilloscope several times and they look like they should, but when I connect up the servo and turn on my power supply it just shuts off immediately.

I know this isnt really an arduino problem, but I thought maybe someone could help.

How do you have it wired? If it shuts off your power supply it sounds like it is going into an over current condition. How much current can it supply?

I have the +5 connected to the +5 output of the power supply, and the arduino, ps, and servo grounds are all connected together. Oh and the control wire is connected to one of the arduino output pins. I've used a few different power supplies and I couldnt tell you the specs on all of them, but the one I will be using for the final product is a computer power supply which says it should be able to supply 20A at 5V.

I guess shutting off isnt really the best description, it jumps up to 5V as I turn the ps on and drops down to around 1V right away.

It's probably a switching power supply and the servo is not providing enough of a load to switch it on. You can put a load resistor on it to get it to work, just make sure it can handle the heat.

silly question.. have you set the psu up to have a power good signal? by jumpering a couple of the pins on the mobo connector. cant remember wat ones

Digger,
I found by googling that other people have added a "power resistor" to their power supplies, is that the same as a load resistor? I think its just a big coil that generates a lot of heat.

and where can I get one of these, radioshack?

Yes, they are talking about the same thing. Radio Shack may have some sand cast resistors that would work. The nice ones have an aluminum body that acts as a heat sink. You should be able to find them at digikey or mouser.

well.... I went out and bought a power resistor (10 ohms 10 watt) at radioshack and hooked it up. I even added a fan to the power supply (yes, it didnt even have one).

A little while ago I fired it up. The servo moved a little bit, and then released its magic smoke. Is it just a bad servo, or did I screw up my power supply?