Problem- Fanuc 6T - Nakamura Tome TMC-3

[mcoulson]

We are having multiple issues with this machine, but I am currently looking for the meaning of the led alarm on the spindle drive. The spindle at times seems to have trouble maintaining RPM, and when the machine goes down it illuminates the "2" red LED on the spindle drive (there are 4 LED's for alarms). Can anyone tell me what the 2 represents?

Thanks!

[cncdiag]

Alarm 2: Speed has deviated from command value.
Cause
Overload
Open transistor module
Blown out fuse on regen circuit check fuse F5 F6
Check fuses on main board
Speed feedback signal is not set correctly

[mcoulson]

Thanks for the reply. We replaced the spindle drive last year and everything worked fine for quite a while, but we recently started having RPM issues and the machine would shut down. We sent the motor to a repair facility to have it checked and they said that a magnet had come loose and damaged a sensor. They repaired the motor and returned it to us, but after installing it we did not even complete one part cycle and the machine went down with a blown fuse in the spindle drive unit (F5 fuse). We replaced the fuse, but it would blow immediately at power-up. We ended up disconnecting what we believe to be a fan circuit to the spindle motor. This allowed us to power the machine without blowing the fuse, but we still have the RPM issue and it shuts down with the "Alarm 2" lit on the spindle unit.

My question now is: In regards to the post above about the "speed feedback signal is not set correctly", is there a POT or something that needs to be adjusted due to the new sensor being installed in the motor (or due to the replacement spindle drive)? If so, what diagnostic would it be and what should it be set at?

[Dan Fritz]

First thing I would do is inspect the tach-generator. I'm assuming that this is a DC motor with a tach-generator mounted under a small end-cap on the motor. If you have one, be sure that the commutator is clean and dry, and that the little brushes are not worn out. I like to have someone turn the motor by hand while I hold a pencil eraser against the commutator.

Next, measure the voltage that the tach outputs as the motor runs (slowly). It should be a steady voltage that is proportional to the motor RPM. A bad tach can cause all kinds of trouble with the motor holding a constant speed.

[jdeere4250]

What is the part num. of the drive unit. like A06B-6044-xxxx, ?
The sensor in the spindle motor is out of adj.
You need an O'scope to do this correctly.
If you need further assist. I can describe it.

[arpimachineco]

Hi, I noticed you have the same lathe as I do. my spindle drive is bad but the tag on it is erased. don't know the spindle drive number a06b? could you please look up on yours and tell me the part number. this will help me locate another spindle drive for my lathe. thanks. myemail is arpimachineco@yahoo.com 818 890 7625