stepper motors glitching

[routercnc]

Hi Irving2008,

I was beginning to think that this was a heat issue, but went back in the garage after work today and the reading direct from the parallel port was full of glitches again. I'm getting very confused by what seems to be perhaps multiple contributing factors.

Started disabling every other port and piece of hardware I could, and disabling AVG at startup, removed printer driver, and still got glitches on the port.

Only encouraging thing from this is that I've managed to ''hold" scope readings on the screen to work out the pulse spacing. Sorry I'm struggling to get these as a good photo (there is no output on the scope either), but I think the following will give you the numbers you need. These are the Mach3 settings, and theoretical pulse spacing:
INPUT
320 steps / min (calibration: stepper per rev, 1/8 microsteps, 5mm pitch)
1500 mm / minute traverse rate (my jog speed)

THEORETICAL OUTPUT
= 480,000 steps / min
= 8000 steps / second
= 8000 Hz
= 125 microseconds between pulses

Comparing this to a typical scope reading shows several pulses spaced at 125 microseconds, then a spacing of about 187 microseconds, followed by more at 125 microseconds. This 187 microseconds is probably:
125 + (125/2) which is 187.5

This means there are several normal pulses, followed by a gap of 1.5 times the correct pulse rate. This is odd, I was expecting missing pulses rather than a mis-timed output. It is more of a jump than a missing pulse. Does this give anyone any more ideas?

Thanks for your continued support and ideas . . .
Barry

Re-read your post, and thought I'd add a bit about the system 3 board and the heat. There are transistors with metal plates which I think are the regulators (see photo in post above). These do get quite hot to the touch within perhaps a minute or two, hotter than the allegro chips. I had considered heat sinks on these, but with the glitches on the parallel port that area of investigation will have to wait. Good suggestions about the cooling spray etc, thanks.