NEED help - i think i have blown my CNC speed controller

Thread Starter

Noidea007

Joined Jul 21, 2021
1
Hello

Need some help - my CNC (dream maker EVO one) was working and got jammed in the material and stopped turning on after that. I thought it was the power unit however as it was not turning on. However as I messed around a little I realised that it was the speed controller as when it was connected it would turn off the power box (only when the red power cable is connected). I check the capacitor and saw it was burnt. the model number for the speed controller is long-20a-opto-v1.5, the capacitor is 25v 330uf. I changed the capacitor and still has not worked. I tried looking for another power controller, nothing matching online.

ANY ADVICE?
 

Attachments

Irving

Joined Jan 30, 2016
2,056
I'm guessing one or more of the MOSFETs on that board have fried from the high-stall current due to the jam. Is this the speed controller for the spindle? What's the spindle motor type and specification?
 

MisterBill2

Joined Jan 23, 2018
9,225
The pictures do not help with the diagnosis, but certainly the indication is that either the controller or the power supply has failed. A capacitor failure due to overload is a puzzle, though. The first thing to do will be to verify that the motor is not damaged from being stalled while the power stayed on. Then check the power supply to verify that it still is supplying the correct voltage. You may beed to replace that driver board, if you do, get a version that includes a motor overload protection function.
 

Irving

Joined Jan 30, 2016
2,056
A capacitor failure due to overload is a puzzle, though.
Its not uncommon, I've seen it before. The capacitor on the board input is a cheap one with poor (often undefined) ESR rating. The motor stalls, one MOSFET fails leadng to massive PWM-related ripple currents on PSU input to board together with inadequate motor wiring (500W spindle motor ideally needs thicker PSU wires than shown there, they look smaller than the phase wires to the motor) causes capacitor to overheat and pop in short measure...
 

MaxHeadRoom

Joined Jul 18, 2013
23,585
Any decent CNC system controller and drive will not allow a motor to exceed the motor peak rating zone for any length of time that would cause damage.
It will go into some kind of shut down mode.
None of the companies adds appear to show the controller?
Also when dealing with servo motors especially, it is far better to use linear P.S. rather than the SMPS version, costs a little more but worth it in the end.
 

Irving

Joined Jan 30, 2016
2,056
Its not a servo motor, its a 500W chinese sensorless bldc spindle motor (3k-11k rpm, ER11 chuck) with a proprietary PWM 24v controller. I've not been able to find that specific controller, though there are plenty of better engineered replacement options. The setup is unusual in that most CNC machines of this size have a seperate PSU with built-in PWM controller whereas here it appears they run it off a separate output of the main PSU.
 

LesJones

Joined Jan 8, 2017
3,472
It would be helpful if you could supply information on the output voltage and current rating of the power supply and any information printed on the motor. (If there is no information on the motor a picture with something included to give some idea of scale may help.) When I looked at you problem just after you posted it my first thought was the motor could be the type of motor used in models. but when I found a picture of one of the machines from the manufacturer of your machine it had a 500 watt motor that looks very like one that Banggood sell. (But the Banggood one is a PM DC motor that runs from a 0 to 100 volt DC supply.) At that point I gave up as I also failed to find any information on your speed controller board. The only thing I concluded about it was there was three output wired which suggested it may be similar to motors used in models. I tried to read the part number of the mosfets on the board but your pictures were not sharp enough.

Les.
 

MaxHeadRoom

Joined Jul 18, 2013
23,585
By the look of the state of the wiring, it appears to be an after market add on??
I can't see any reputable manuf. putting out a product like that, even for China!
It almost appears to be an RC controller ( long-20a-opto-v1.5) ?
If it is the spindle, then definitely a mistake to use one of those SMPS supplies.
 

Irving

Joined Jan 30, 2016
2,056
Guys, the TS probably has no more info than what's on the EVO website or listed on one of the many ads on Banggood/AliExpress. The spindle motor is a generic Chinese one copied by many and sold by many more...

1626899117618.png1626899196886.png
 

Irving

Joined Jan 30, 2016
2,056
Yes, that's one of several, but that implements the industry standard 0 - 10v input for speed control, rather than PWM input as in RC systems. I know PWM->Volts is relatively simple but that's no longer a plug & play change to the existing system.
 

LesJones

Joined Jan 8, 2017
3,472
Hi Irving, I agree that there are a number of versions of this spindle motor from Banggood. (I only knew about the version with the 100 volts PM DC motor as I have bought that version.) I suspect the speed controller from the TS's machine uses the same standard as used in RC models. This is the reason I asked the TS for the power supply rating and information on the motor. I think we are all just guessing that the motor looks like the Banggood one as one product from the manufacturer seems to use that motor. I am hoping the TS will eventually answer questions so we can help with his problem. Even then I don't think he will be able to tell us the communication standard used between the CNC controller and the speed controller. I think the best to hope for would be to find the part number of the MOSFETs on the original speed controller and replace them.

Les.
 

Irving

Joined Jan 30, 2016
2,056
Hi Les, I agree, but I suspect the TS is more an end-user than system engineer. I'm not entirely guessing as I have the 1000w/180V version of that spindle with an ER20 chuck.
 
Top