Hello - I am working on an older cincinnati falcon turning centre and trying to find out what is causing intermittent problems with a variety of things on the machine. Sometimes after running through a program, the chuck will not open to allow you to take the part out, no matter how many times you push on the pedal. The output relay for chuck open is operating according to the red light on the rack for it, but the hyd. solenoid doesn't operate to open the chuck. No alarms are generated at all for this. Then if you power cycle the machine and try again, the chuck will open no problem.

Also sometimes during cutting or in cycle the machine will give alarm 39-50 or alarm 39-11 or even 39-36. These are all associated with the main spindle and cause everything to stop. The machine has lots of power for taking heavy cuts, and the cooling blower for the main motor is functioning properly. It seems like the spindle drive enable signal might be dropping out or something like that? The siemens spindle drive unit doesn't display any error codes when this happens so I don't think it's being overloaded.

Lastly, the contactor that operates the chip conveyor motor will occasionally begin to bounce quite severely, making an awful buzzing noise - even though the coil voltage is correct and the amperage draw is within reason. The contactor is brand new as well so I don't think old age is the problem - it only does this sometimes - other times it closes and holds perfectly. Has anyone got any ideas what to look into on any of these problems?