[shbach]

Hi,guys I have a 1992 bridgeport vmc 1000/20 with a heidenhain tnc 2500 control. The servos are fanuc a06b-6050-h402 for all three axis.The problem i am having is when i try to home the machine ,Iget an gross positioning error z-d . Ihad fanuc techs here to look at servo unit , They sent it out to be looked at and when it returned i still have same problem. When i do voltage checks from the drive transformer to the drive ,one of the legs is low with the drive disconnected the voltage is equal. I still think the drive has a problem but not getting anywhere with fanuc . Any other possibilty on what the problem could be. Iam at witts end with this problem machine down for a month now. thanks shbach

[gus]

have you checked to see if the other axis home? you can temporarily change the homing order in the parameters.

IF the techs did their job and the drive is good, check wiring to and from the drive and to and from the drive motor

[gridley51]

Why are you assuming the axis drives are the problem?
A "D" error on Heidenhain is usually to do with standstill supervision.I`m not too sure with the 2500 control but have a look at parameter 1110.
Try setting that parameter to the maximum allowed to see if it makes a difference.

Edit: As someone mentions,if safe to do so,change the reference sequence.You can even take the Z axis out altogether for proving purposes.