Dougbeast: Before you go much further, check the jumpers on the servo and the CNC power transformers. These jumpers are used to adjust for your shop's line voltage, and every time a machine gets moved to a new shop, you're line voltage is likely to be different.
Inside the CNC cabinet (near the power supply) there should be a single-phase transformer with a set of taps for line voltages of 190 to 550vac. This transformer has secondaries (outputs) of 100 and 200vac. Measure the outputs and see how close they are to 100 and 200 volts. If they're more than 5% low or high, you may want to change the taps so they are closer to their intended voltage. In Japan, the "standard" voltages are 100v and 200v, and the transformer is designed to give the CNCs power supply the right stuff.
Also, somewhere near the servo amplifiers, is a larger 3-phase transformer with multiple taps. These jumpers can also be adjusted to give the servos what they need as an input voltage. Chances are, the servo transformer will be jumpered for the same line voltage as the CNC power transformer, so if you have to adjust the small single-phase transformer, you'll probably have to adjust the servo transformer as well.
Making the servos run smoothy on a Fanuc 5 requires a bit of work (with a voltmeter and an oscilloscope), but the results are well worth it. If a servo makes any noises other than a nice "hum" as it moves, then you need to look into things. A lot of machines have ballscrew covers or way covers that make funny noises, but those are not worth worrying about unless they're binding somehow.
One common problem on these old SCR servos was having a blown fuse, which would cause the servo to run on a single phase (sounds rough, and does not have much torque). The 3 "indicator" fuses on the back of each servo amplifier have little "flags" that are suppose to pop up when the fuse blows, but if the flag sticks, the fuse can blow and the control wont' shut it down with an alarm. The result is a servo that runs on a single phase.
As with any used machine, DOUBLE CHECK to be sure the way lube is getting to the right places, and that the ballscrews and nuts are being properly lubed also. Clogged lube lines are a real problem in used machines.
For servo tuning on a 5T/5M, I'll be glad to write up the procedure, but it does take some skill and a few basic tools, including an oscilloscope.  |