how change 3 phase spindle speed

Thread Starter

steevens

Joined Feb 14, 2021
7
my cnc 3 phase spindle have a fixed speed 21000 rpm and i need to reduce the speed, can i add a potentiometer in the integrate pwm circuit or change some components to reduce the fixed speed
tanks you
20210214_131504.jpg
 

strantor

Joined Oct 3, 2010
5,543
On the right side of your pic is a yellow and red wire. Can you move the yellow wire and take a pic of what it says under?
 

MaxHeadRoom

Joined Jul 18, 2013
23,092
3ph?
The board has BLDC on it ?
Is this a PM field motor?
What is the application for the fixed speed?
What is the motor data plate show?
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
23,092
Almost seems like it has options and the drive was set up for one particular task or function, particularly the area Strantor pointed to.
Max.
 

strantor

Joined Oct 3, 2010
5,543
These motor appear to have also been used in the low end CNC market, How come the spindle has been set at a fixed speed?
Max.
I suspect the 3 pads on the PCB at right are either for connection of a speed pot or hi/med/lo digital inputs, which are bypassed by the red and yellow wires for constant hi speed. There is also a spot for what I suspect to be a trim pot beside these pads ("ADJ2") which has a fixed resistor soldered in place.
 

strantor

Joined Oct 3, 2010
5,543
I think this is a dumbed down version of a more fully featured board. You may be able to add the missing components to attain the intended features but it will be a guessing game, and a hard one at that. I doubt you will be able to find schematics for it considering how they sanded the part #s off the chips. They don't want you to figure this out. They went out of their way to stop you having any idea how it works. I would throw it away but not before stomping it into pieces. Then I would buy a proper BLDC driver with common sense features and documentation.
 

MaxHeadRoom

Joined Jul 18, 2013
23,092
According to the manual the spindle is 21,000 rpm.
I see the ability to enter the M3 command but no Sxxxx command?
Was the speed variable before?
Being a CNC table I would expect the S command would be in effect, at least for a minimum value.?
Max.
 

strantor

Joined Oct 3, 2010
5,543
no the s command dont work its just 21000 rpm probably because its a wood router but i want cut aluminium and for that i need to reduce rpm and i dont think the support show me how hack this board :)
If you're on board with the idea of stomping the board to pieces (which you absolutely should be, in my humble opinion) then you have nothing to lose. Why not try desoldering the red wire from the "H" pad and resoldering it to the "L" pad? It might fry your board or it might do exactly what you want. I make no guarantees.
 

Thread Starter

steevens

Joined Feb 14, 2021
7
I suspect the 3 pads on the PCB at right are either for connection of a speed pot or hi/med/lo digital inputs, which are bypassed by the red and yellow wires for constant hi speed. There is also a spot for what I suspect to be a trim pot beside these pads ("ADJ2") which has a fixed resistor soldered in place.
i am not good in electronic, but i like test lol
do you mean replace (adj2) resistor with trim pot
 
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