Hi everybody,
I´m new to this forum and needing some advise as I´m trying to troubleshoot a problem with a cnc milling machine.
The milling machine has 2 pcbs, the control stage and the power stage; the power stage feeds the control stage, 3 steppers (X,Y,Z) and it also controls 3 relays (milling motor and auxiliary pump).
Basically, when I turn the machine on everything seems to be normal. It even has an autocheck to check the steppers and optoswitches. I tried the autocheck and everything is fine but when I start a job, as soon as the milling motor starts, the 2A "slow blow" fuse blows, turning everything off.
At first, I thought that the 1/4HP motor was the culprit but I checked the windings and the capacitor and they were fine. As I had another motor and cap I swapped them but the problem still exists. Motor is not the problem.
As I also have a spare control stage I swapped them, even though I thought that the former control stage was ok, and the problem continues.
So far, I narrowed the search to the power stage.
I then disconnected the motor and connected a 100W bulb instead.
When I turn on the machine it starts up normally, steppers move back and forth as usual and when I start a job the bulb lights. So...
The power stage seems to be working?!
The only bad thing I found was a value shifted resistor from a snubber (showing 133 ohms instead of 120). I have already replaced it.
I thought that maybe the main motor relay is failing to contact properly, maybe it can still handle a 100w bulb but not the current draw at motor startup? Any ideas before I start replacing components?
I would very much appreciate your input.
Regards.
I´m new to this forum and needing some advise as I´m trying to troubleshoot a problem with a cnc milling machine.
The milling machine has 2 pcbs, the control stage and the power stage; the power stage feeds the control stage, 3 steppers (X,Y,Z) and it also controls 3 relays (milling motor and auxiliary pump).
Basically, when I turn the machine on everything seems to be normal. It even has an autocheck to check the steppers and optoswitches. I tried the autocheck and everything is fine but when I start a job, as soon as the milling motor starts, the 2A "slow blow" fuse blows, turning everything off.
At first, I thought that the 1/4HP motor was the culprit but I checked the windings and the capacitor and they were fine. As I had another motor and cap I swapped them but the problem still exists. Motor is not the problem.
As I also have a spare control stage I swapped them, even though I thought that the former control stage was ok, and the problem continues.
So far, I narrowed the search to the power stage.
I then disconnected the motor and connected a 100W bulb instead.
When I turn on the machine it starts up normally, steppers move back and forth as usual and when I start a job the bulb lights. So...
The power stage seems to be working?!
The only bad thing I found was a value shifted resistor from a snubber (showing 133 ohms instead of 120). I have already replaced it.
I thought that maybe the main motor relay is failing to contact properly, maybe it can still handle a 100w bulb but not the current draw at motor startup? Any ideas before I start replacing components?
I would very much appreciate your input.
Regards.