[sliptonic]

I have a YCM-30 milling machine with SDR 1525-12 amps and servo dynamics motors. It's been running well but recently developed a problem with the Y axis.

On long jogs at about 50 IPM, the amp will halt. The over temp/RMS LED is lit but the heatsink is cool. I guess this is a dual purpose LED indicating either of two conditions. Since the heatsink is cool, I assume it's telling me I have an RMS condition.

I can't feel any binding in the Y axis when I turn it by hand and the problem only shows up on long jogs. For example, if I home the axis where it's seeking the switch at 25IPM, there's no problem. If I rapid back to the middle at 200IPM, there's also no problem because it doesn't take very long. But if I rapid back at 50IPM, it will give the error almost every time.

The manual I have says the RMS condition exists if the amp has to deliver peak current for a period too long. It also says that the problem can be caused by a stalled or binding motor or a shorted armature.

Like I said, I don't feel any binding but I don't know how to test for a shorted armature.

Any other ideas or advice are appreciated.

[sliptonic]

After trying about thousand things, I convinced myself the issue wasn't mechanical and went through the amp tuning again. I adjusted the CMP up a little and the axis movement smoothed out considerably. The RMS doesn't trip anymore.