[parkerbender]

Hello everyone,

I'm having some trouble getting spindle drive faults on my 91 bmc40slv. It will run fine for 10-15 minutes, then when ending a cut, it won't slow down, the tach will go to zero, and the spindle will freewheel... Does anyone have any clues what the most common reason for this is? It's done this before a couple isolated times, but now it's doing it consistently every 15-something minutes... not on the same tool every time, and not the exact amount of time, actually the last one was in the middle of a cut as well... so, is this usually a connection problem, or can a person clean the encoder? I'm away from the machine for a little while so I don' have the letters on the readout, but i'll throw them up when i get back there... just got a rush order today, bad time for the hurco to quit... (mumble, mumble) anyway, thanks again for any ideas or insight!!!

-Parker Bender

[parkerbender]

The display has -OU on it, and the INP, IPF and LG led's are on, the rest are off... When it's mad, it says -OU right away, it doean't follow the spindle down.

Thanks,

-Parker

[bloke]

Parker, it sounds to me like you have a faulty braking transistor there. The OU error is overvoltage on the DC side of the drive. It's sometimes caused when the transistor that diverts the braking energy from the motor fails and doesn't dump the excess to the braking resistor.
It's found underneath the front cards on the spindle drive.

It could also be a phase missing on the input (unlikely as you'd see other things failing).

After having had a look in the Yaskawa book, it seems that it may also be the winding select contactor. Does it do it at say, 4000RPM as well as 500RPM?

[parkerbender]

It only did it three times this evening, I let it sit for a bit, then it worked for the rest of the run... It never was running as slow as 500, this is all 6061 stuff with .250 and .125 cutters, but, it did do it at say 10k and 6k... Also, I rearranged a couple of blocks so it wouldn't drop rpm from 8k to 4k for a finishing pass, which may be working the braking circuit less hard, and making it work... no clue. anyway, is there a forum that you prefer, I hate to chase you back and forth from here to PM...

Thanks again, you're always a lifesaver!

-Parker

[bloke]

I prefer the Zone. I've had a few nutters on PM.