mystifying 320 problems

[senor J.]

Hello all. I have three gecko 320s hooked up on a router I finished about 2 months ago. They all worked well for about a week no problems at all. It got cold here and I havent done anything with them since then. It was finally warm today so I went to start it up and the -5v that comes from the computer and is hooked to the common ground of the power supply burned up. The + 5v that goes into the gecko for the step and direction signal didnt get warm at all. Its blowing my mind because the wiring for the + 5v from the computer is so simple and nothing has changed from the last time I used it. It worked fine then and now all of the sudden the common -5v burns itself up. when I take the +5v out of the gecko I can turn the fault light off and the servos will just sit there holding there position great. The problem arises when I hook that +5v back up to the gecko and the -5v up to the common ground. It just burns that -5v right up and the +5v doesnt even get warm.
So anyway I decided to trouble shoot and do away with the 5 volt from the computer and instead I used a wallwart with +5v 1amp just to see what would happen. That way there would not be enough amperage to burn the -5v up. what happens then is when the +5v is applied to the gecko the servo goes from holding its position quietly to making jerky turns of about 1/10 revoltion per jerk all in the same direction of rotation, and the noisy jerks are periodic about ever 1 second
Ok you may be thinking possibly a short some where in the 5v from pc wire. Not a possibility. I inspected it with extreme care and there simply is no short. ITS BLOWING MY MIND. its as though 1+1=3 !!!!!
help will be appreciated. thanks
Senor J

[Mariss Freimanis]

Why would you connect the computer -5VDC to ground? That shorts-out the computer's negative 5V supply and burns it out.

Mariss

[senor J.]

the diagram I have says that the -5v should be connected to the common ground on the capacitor of my power supply so that everything is connected to a common ground. It is connected to the - terminal on my capacitor that provideds the 70 volts for the motors. are you saying that that does not work? It did a few months ago without a problem. thanks for the quick reply mariss

[senor J.]

My diagram is all screwed up either that or I'm screwed up. probably a little bit of both, any way It works now. Thanks for pointing out the obvious mariss. Whats really weird is it worked for a couple of weeks with the screwed up wiring.
let this be an encouragement to all you would be cnc dudes no matter how much you dont know there's always people like me running in circles wondering why Im not going anywhere.

[Mariss Freimanis]

You can pick up +5VDC from your PC on pin 1 of your game port (DB-17 connector). Take it to the G320 COMMON terminal. Do not connect your PC ground to anything on the drive. Only STEP, DIRECTION and COMMON (+5V) connects back to the PC.

Mariss

[eman5oh]

PC supplies have both positive and negative voltages when refeneced from ground. The -5 and the +5 will give you 10 volts, but the -5 lines usally are reated less than a amp and the +5 are usally rated around 28 amps or so.You can not connect both the +5 and -5 to something that is grounded. I belive that you sould have had a black wire (dc ground from the pc) and a red wire (+5 vols dc from pc).

[Mariss Freimanis]

It's amazing how keen 20-20 hindsight is. Don't feel bad; I've run in many circles while overlooking the obvious.

Mariss