I've got a Miyano ANC-45, circa 1986, with two turrets, a subspindle and live tooling on the main turret (main spindle positioning only, not a full C-axis and not on the sub). The control is a Fanuc 11TT.
The sub spindle drive is currently giving me an alarm. The drive is a Fanuc A06B-6052-H002. The alarm LED's on the drive are indicating Alarm #2, which the drive manual describes as "Speed is deviated from the command value". The funny thing is, that alarm lights up the instant there is power to the drive, before the CNC control is even turned on. The LED lights up at the same moment the green power LED does. At that point I wouldn't have thought there would even be a "command value" for the speed to deviate from.
There is an encoder on the spindle, separate from the motor. With the CNC control on, turning the spindle by hand does change the speed readout on the CNC in an apparently accurate manner, so it looks like that encoder is working. The DC voltages at all the check terminals on the drive associated with the motor's speed sensors seem to be in the right ballpark; I just ordered an oscilloscope, so I can check that more properly this weekend.
The manual also mentions some fuses, the Transistor Module, and the regeneration circuit as possible causes for this alarm. The fuses are all good, and the regen resistor measures at 15 ohms, which is correct. I checked out the transistor module the best I could with a multimeter; all 6 transistors in there measured the same for voltage drop, and nothing seemed too far out of line.
Needless to say, I'm having trouble figuring this one out. Has anyone ever seen anything like this before?
I checked the terminals related to the speed sensor circuit with an oscilloscope. Everything looks exactly like the manual says it should look. So the pulse generator is working, the encoder is working, and I'm still getting alarm #2 on the spindle drive. The lathe won't do anything until I get this figured out. I'd really appreciate some help.
I figured out how to lie to the control and make it think everything's good with the subspindle drive missing (jump "ESP1" to ground and "ALM1" to "ALM2" on the 50-pin connector, if anyone's wondering), so obviously I don't have a subspindle at the moment, but at least I can use the machine with just the main spindle now. The current parts don't use the sub anyway.
I think we're actually going to replace the drive with a brand new Mitsubishi VFD. We figured out what all of the pins in the connectors are doing, and it doesn't look like there's really anything complicated going on. Fortunately this one uses a simple 0-10V signal for speed, not the goofy binary signal, and there's no orientation board.
In the 50-pin connector only 20 of the pins have wires attached to them, half of those have to do with the orientation board that this drive doesn't have, and the rest are simple ins and outs that the Mitsubishi drive should have no trouble working with. The new VFD will give us better diagnostic tools, better reliability and easier adjustments. It's also less than half the price of either of the two PCB's in the Fanuc drive.
I'll be sure to document the process and post it on here. Maybe I'll fix the old drive and sell it off then.
when I suspected optocoplers I just replaced them.
instead of Mitsubishi drive you can use KEB Combivert F5, it has got orientation option if you buy additional PCB
I just ordered the Mitsubishi VFD and the braking resistor module, new through a distributor, for under $400. I don't need orientation on the sub spindle, so the D series is adequate. Mitsubishi makes some of the best VFD's on the market. It looks like that KEB is quite a lot more expensive, and I'd bet it doesn't even perform as well as the Mitsubishi.
the main problem you will face to is 12-bit speed reference.
I know some Fuji drives understand it, but it can require optional card
hope you Mitsubishi drive is 220V three phase
This machine doesn't use the 12-bit speed reference. It uses a 0-10V signal instead. The pins on the 50-pin connector that would be used for the 12-bit code don't even have wires going to them. And don't worry, the voltages on the new drive are correct.
As you have checked the power side over on the drive and it checks out ok I would get another top board for it..a 10 minute install and you are back and running!!
Fanuc AC Spindle Drive Alarm #2 at Startup
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