What have I done!

[artmin]

I have a Heiz High Z 1000T which I use daily and it has proved as solid as a rock for the last 6 years. I was getting fed up replacing the Kress spindle every year so I have started to convert over to a water cooled VFD. Wanted to add a no voltage contacts for switching the VFD (DCM+FOR) so I thought the neatest way would be to add a 12v relay with volt-free contacts inside the controller and piggy back the 12v relay that switches the existing 240VAC supply to the Kress, which would then be left redundant but still there if I needed it. Simples, I thought & now the trouble has started

I have now removed my additional relay to try and get the machine to work again, though I think something else must have been upset. Is was the PSU board that I had removed and took lots of photos to ensure that the leads were reconnected correctly. What is happening now is when the controller is connected to the steppers and powered up, everything seems normal and the steppers are holding. When I connect the 25pin PP cable to the PC port and powered up, the steppers all make a horrible noise and are creeping slightly. It does this only when connected to the port of the PC (any PC in fact as I tested it with my backup PC) but it is fine when the 25pin cable is just connected at the controller end. Does anyone have any ideas please as this is now way beyond me.



The rough rectifier mod at the top of the photo was made years ago, after the solder kept melting on the diodes of the rectifier OP, but that has been faultless since.

Many thanks in advance,

Gavin