Hello Peter,
Thanks, but I'm not sure on this one. We have been thinking on this and the motor is starting to sound ropey as it did with the original motor, which has set us thinking back to the motor itself.
Anyway, since last night the engineer has come back to me and said that the filter is nothing to do with the spindle driver board. The feed to the driver board is seperate - to check this, we took out the inline fuse to the filter and the only difference that it made was that the tacho readout on the front of the machine didn't work, which is not a problem as the speed is controlled from the computer. The motor ran up just the same. so the filter is nothing to do with the motor.
Now the motor only runs for around 15-20 secs before it pops and as I said, it sounds like a two stroke on misfire!.
I checked in the top of the motor whilst it was running and it's like a firework display in there - which points to possible brushes problem (as i2i suggested earlier) which I couldn't believe as the motor is a brand new unit - only 12-14 hours on the clock - that was why we were looking for other causes. I will check the brushes in the morning.
The only thing that is different on this machine from its original set up (in the spindle motor area), is that we are running it the opposite direction as we have a toothed belt drive to achieve 1 to 1 as opposed to 1.85: that was on original gearing to get the spindle speed up to higher revs for the small cutters we are using. As we've taken out the gears, consequently the motor runs "backwards".
As far as we knew, DC motors run in either direction - but maybe we're worng and it is this that's causing problems and taking out the brushes? Does anyone know?
Regards,
GeoffB