Denford Software & Machines

Hello

Bought a Novamill & spindle speed is stuck on a single RPM (around 4500).

RPM adjust pot on unit controls software on PC so I know that side of things is working.

0-10v to motor control is at constant voltage around 4.6v if I remember correctly regardless of RPM selection.

Looking at the Baldor board (F391 issue 1)
There's a pot trimmer on the 0-10v circuit, I'm assuming this calibrates RPM. Rotating this pot has no effect on 0-10v motor signal.
Interestingly, there is a 4.1 Ohm resistance across the pot which seems a little odd. This resistance can be metered across Vcc & Gnd pins of the opto-coupler & also across 0v & 5v output pins of 12v DC - DC converter.

My next plan is to scope the output of D71054L (U11) ic which provides the signal to the opto-coupler to determine if the issue is located on the isolated o/p section, or on the digital side.

In the meantime - does anyone have any advice on this issue? Could it be that this particular mill was programmed to run at a fixed RPM for some reason?

Thanks

Update on this issue

Ended up replacing 12v DC-DC converter, SMD capacitor & op-amp on control PCB isolated output which got the 0-10v control signal working again but the motor would still not spin correctly. Further investigation revealed the Sprint motor control board minimum speed setting was at fault & not providing the common connection required for the 0-10v control signal. I suspect the pot maybe faulty but I overcome the problem by connecting negative wire of 0-10v signal to sprint board common pin.
Replaced some capacitors & soldered dry joints along the way. Everything is up & running again

I have a similar issue but the root cause might be different. May I ask, does the 10V reference output on your Sprint board correctly outputs 10V?

The sprint drive will have a 0V 10V and analog in terminal.

If you connected a pot to this you would then be able to control the speed from the pot proving thet the drive is working.

Take care as the Sprint is not isolated but the analog out of the nextmove is iscolated and should change between 0-10V with speed request.