Desktop Mill - VFD - Replacement

Last updated: 05/30/2025

Desktop Mill - Variable Frequency Drive - Replacement

AD0561

Revision A - 5/2025

Introduction

This procedure will tell you how to replace the Variable Frequency Drive on a Desktop Mill.

This Procedure Applies to the Following Parts:

93-3321 110V VFD REPLACEMENT KIT DESKTOP MILL
93-3323 VFD REPLACEMENT KIT 220V DESKTOP MILL
93-3237 SERVICE KIT 120VAC VFD DESKTOP MILL
93-3238 SERVICE KIT 220VAC VFD DESKTOP MILL
93-3950 PROGRAMMED VFD 2HP 1PH 120V DTL
93-3949 PROGRAMMED VFD 2HP 1PH 240V DTL

If VFD replacement is needed and the customer has:

69-2120 they will need 93-3321
69-2220 they will need 93-3323
69-2120A they will need 93-3237
69-2220A they will need 93-3238

Replacement

1

Push [POWER OFF].

Unplug the Desktop Mill.

NOTE: Be sure to unplug BOTH the control pendant and the Desktop Mill power cords, as current runs from the pendant to the mill.

2

Remove (x9) BCHS 6-32" from the rear panel and remove the panel.

3

Open the VFD's front cover, and use a screwdriver to carefully disconnect the power cables, ground cables, and remaining input/output wires.

The left image is a Schneider VFD, and the right image is a Delta VFD.

4

If your machine currently has a Schneider VFD, unscrew the two Philips head screws to remove the VFD.

Delta VFDs are held in place with four screws, one at each corner.

5

For machines initially built with a Delta VFD:

Some desktop mills built with a Delta VFD do not have a bracket. If this is the case, no bracket is needed.

If your machine currently has a Delta 110V VFD, unscrew the four Philips head screws from the bracket to remove the VFD [2].
If your machine currently has a Delta 220V VFD, unscrew the two Philips head screws from the bracket to remove [3].

For machines initially built with a Schneider VFD:

Note: If installing a Delta VFD on a machine built initially with a Schneider VFD, a mounting bracket [1] P/N 25-15216 will need to be installed. Before proceeding, this is done with two PPHS 6-32 X 3/8 and washers included in the kit. It is possible that your machine may have the necessary holes to mount the Delta VFD, and the bracket will not be needed.

To install a Delta 110V VFD, install four PPHS 6-32 X 3/8 and washers into the mounting holes shown in BLUE [2].
To install a Delta 220V VFD, install two PPHS 6-32 X 3/8 and washers into the mounting holes shown in RED [3].

6

Carefully reinstall the power, ground, and input/output wires according to the reference table.

*Important: For Delta VFDs, the Wht/Brn wire should be put into RB even if the wire is labeled RA. This will reduce the chance of erroneous alarms.

Note: The blue wire may be installed into either DCM port on a Delta VFD.

Note: Each wire has a label indicating which port it should be connected to on the VFD. The three-letter code in brackets indicates the port on a Schneider VFD, and the three-letter code without brackets indicates the port for a Delta VFD.

Reference Table
Color	Function	Schneider	Delta
Red/Wht	Enable	LI1	MI1
Red	Speed	AI1	AV1
Wht/Brn	Fault	R1A	RB*
Brn	Common	R1C	RC
Wht/Blu	Common	COM	ACM
Blu	Common	COM	DCM

7

Reinstall the rear panel with (9) BCHS 6-32".

Plug in the machine and control the pendant.

Push [POWER ON] and test machine operation.

NOTE: If the spindle does not start up properly upon first power up, cycle power and try again. If the problem continues, stop and call Haas Customer Service.