[bbrreid]

Hi, can anyone help me with my yaMAZAKi cnc lathe.
2 weeks ago my hyd. chuck burst the 3 small cap screws that attach the drawbar

to the chuck, so I switched off the machine and took the chuck off for repair. today

I powered up the lathe and have an LED telling me Field Loss reset with contactor

s2 which I did with no result. I must point out that the chuck is still off the machine ,

could this be the cause of the fault, should I repair the chuck to drawbar. the

spindle will not work even in manual mode.
thanks
Brian

[HuFlungDung]

Is this a DC motor? Field loss is potentially a deadly condition for your spindle motor, because it could runaway and never come back....er...overrev and explode

I suppose, first get a competent electrician to help you troubleshoot the connections. You may have an open on the field circuit, or, perhaps a failed power supply on the field circuit.

Whatever you do, don't try to work-around the alarm. It needs proper fixing. It should have nothing to do with chuck or drawtube removal.

[Al_The_Man]

As HU says, it could be potentially dangerous, fortunately most DC drives have built in field loss protection, You should have two field terminals on the drive to check for voltage, typically 100~140 DC.
Al.

[bbrreid]

Thanks guys I will have a look Sunday

cheers
Brian

[bbrreid]

Hi,
in work looking at spindle drive Mitsubishi DL SCZ - 11 K TD 830A
Field circuit 65v 10 amp max motor alarm light still on chuck back on and working fine. when powered up the 15 amp fuse blows. after 3 attempts the overload light came on and smoke came from under the machine near the spindle motor and the spindle "Load meter" shot away up near the red I think the spindle motor needs looked at as the comutator is a bit grooved.the machine dates from about 1980 but it has been a good machine. we are only turning light work aluminium parts

[Al_The_Man]

Sounds like the brushes and brush holder needs a good inspection, if not checked, over several years the carbon dust accumulates and can, in some cases cause a flash over to ground of the brush gear.
You should do a number on the motor if it has not seen any work since 1980, and also check the DC servo brushes while you are at it, don't forget the spindle tach brushes.
If you have field voltage, check the field winding resistance.
Al.

[bbrreid]

Thanks for the reply Al, I am going to attack this job today. I do some work for a company called Scottish Electric in Dundee who repair large motors so as soon as I get the motor out of the machine I will have them check it over. I also meant to mention there is some swarf in that area around the motor as the top cover must have been removed when lifting the machine for shipping to my place. I checked the large brushes on motor and the Tacho and they appear ok
so lets just hope its not the spindle drive.
cheers
brian

[bbrreid]

just an update.
motor now away for a clean and inspection , hope I dont have to buy a new one
Brian

[bbrreid]

Just an update
motor repaired and working like new
repaired by local company Wardhu electrics
thank you to every one who replied

Brian