[billsnogo]

I have a 93 vmc40 with dc servos and every time I power down the machine I home it so I don't have to hand jog for the startup. Well last week I had a x axis fault, as it looks like it may had overtraved when I was running my warmup program for the axis and spindle..... never did that before.....hmmm. Powered it down and hand jogged it to the cs position and all was well. Next time I start up the machine I now notice that my x does not stay lined up when powering up the machine, it is off by 1/2" or so. I am nervous this is the beginning of a problem and want to squash it now. I do believe my power supply is going bad, but still can not find a wiring diagram allowing a person to use a pc power supply.

Anyone have a similar problem? Any help is appreciated.

[Tedger]

I have a 95 with DC servos and motors. It started doing the same thing about 4 years ago. I did swap out the motor with a spare I have but that didn't help. I was going to try swapping amplifiers to see if the problem followed the amp but I got lazy.
Now I just make sure to check that it cold starts at the proper position every time. If not, I just jog it back and hit "CS".
It seems to happen when I shut the power off after homing it. It's never given me any issues while I'm running so I quit worrying about it.
BTW, I did check the power supply and it's good.

[gaswiz69]

Check the X axis position after you power down and see if it moved. If so, pressing the e-stop before power off should take care of it. What could be occurring is
A)if moving at power off, X drive is not going into a power down state as the power supply is drained, ie brown out condition, estop should help
B)if moving at power on, drives are powering up before the CNC computer comes online, check solid state relays on amp chassis, again estop should before power down should help with this.