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Craftex CX601 Spindle Control

Goodday to all ... hoping to validate my next move before destroying my control board, lol!

OK, so the CX601 comes with a variable speed DC motor controlled by a potentiometer. The control board is a KBIC IC-AAC, here's a picture:
I'm in the process of wiring this up to my converted CNC machine with the Centroid Acorn controller and I want to replace the potentiometer with voltage coming from the Acorn board.
From what I've read, the P1, P2 and P3 lines coming from the potentiometer need to be replaced by voltage to the P2+ and F- connectors on the KBIC board.
It is recommended to install a signal isolator KBSI-240D from Acorn to the KBIC for signal isolation.

I've tested output voltage from the Acorn and it's in line with maximum spindle speed setup in parameters (0-10V). The KBIC documentation states that the voltage must be set between 0 - 7V, which is easily accomplished with the KBSI-240D isolator board.

So here's the question:
The P3 line (blue) is only between the control board and the potentiometer, so just need to disconnect.
The P2 line (brown) is connected to the potentiometer and also to the magnetic switch, do I disconnect from both and connect the (+) voltage from the KBSI-240D?
The P1 line (black) is connect to the potentiometer and to the filter, do I just disconnect both these lines?
Any help would be appreciated :)


I Tried, It Broke
Premium Member
Disconnect P1, P2 and P3 so removing wires going to filter and magnetic switch?
Regarding the warning - if care is taken for the wires between the KBSI unit and the P2 and F- connections, how can grounds get mixed up?
1-2: 110V Neutral
3-4: 110V Line
5: Analog Ground from Acorn
6: Analog Out from Acorn
7-8: not used
9: ground to F- (min pot adjusted to 0V)
10: 7V to P2+ (max pot adjusted to 7V)

Thanks for the response!


I Tried, It Broke
Premium Member
Yes, remove wiring to filter and mag switch, They are irrelevant once the pot is removed.

I advise not using the word ground in regard to the F- connection. It’s not grounded, and if you’re like me, you won’t remember this years after you do the mod and need to do some repairs. My original hand-sketch wiring diagram said GND for the isolator to F- connection, and that’s what I did when I put it back together after the repairs. POOF! and $120 for a new controller board.
Follow up: have wired the KBSI unit to Acorn and to the F- P2 connections on the spindle control board. When trying to start the motor, I hear the contactor kicking in but there is no display on the readout and nothing happens when commanding a spindle rotation. Have removed the pot completely with connectors going to the magnetic switch and the filter.

I'm kinda stuck ... any ideas?


I Tried, It Broke
Premium Member
Can you post a photo of the filter and mag switch part number & connections? There’s something funky with the pot connectors that’s different than my older version. Thanks
By removing the pot the magnetic switch no longer connects the filter B connexion to the 7V power source, could this be the problem? Don't have the model number of the filter board. 1676827702977.png
Was trying to get it up and running before returning to the original state ... I'm mesuring the correct voltage from the KBSI-240D, ie, 0-7VDC between spindle speeds of 0 and 3200 coming from Acorn. Could I simply plug the motor into the KBSI unit without passing by the speed control board and the filter? Would make the front controls and speed display inoperable but, heah, I would have direct speed control from Acorn.I could also hookup the motors to the relays from Acorn and configure the M03/M04 spindle direction output.


Premium Member
Speed control only from Acorn would be fine. I don't think you'd miss the manual controls - and if so perhaps a pendant is in your future? I did not buy a pendant as it is a bit pricey from centroid - instead I bought this weird USB puck thing. I'm using it for manually moving the axis around.



I Tried, It Broke
Premium Member
Stuff to check:

Replace all the original wiring as per the factory schematic.

Does the KBIC motor controller work properly without the Acorn and signal isolator? If so,
> leave the original speed control pot connected, but remove the centre pot connector wire from P2.
> connect your signal isolator and Acorn as per instructions, to P2 terminal and F-. If everything is good, you should be able to control motor speed with your Acorn device.

And now I’ll yell:

Power connected to a KBIC controller without a motor armature in circuit will immediately destroy the controller. A reversing relay is an open circuit while moving from FWD to REV. Poof! Another $120 controller mistake I did.

See page 9

OK, @whydontu, as per schematic, P2 is also connected to the magnetic switch on terminal 12 which in turns transfer the voltage to terminal B thru terminal 11 when in Forward or Reverse: 1676940087682.png
Should I maintain this connection to terminal 12 (I would beleive so)?


I Tried, It Broke
Premium Member
OK, @whydontu, as per schematic, P2 is also connected to the magnetic switch on terminal 12 which in turns transfer the voltage to terminal B thru terminal 11 when in Forward or Reverse: View attachment 31013
Should I maintain this connection to terminal 12 (I would beleive so)?
yes, leave P2 to 12. My thinking is this connection configuration will establish that all other functions work, the only thing you’re removing is the 0-7 volt signal from the pot. Leaving the outer two terminals from the pot connected just provide a fixed high-value resistor from P1 to P3 that won’t affect speed control.
Final update - line from L2 to filter was disconnected somehow during my manipulations. Going thru each wire's continuity I found the faulty one. Luckily nothing blew up :). Removed the pot completely including lines to magnetic switch and filter. Now have spindle control from Acorn using the F- and P2 connections to the KBSI-240D. Thanks for all your help.