Dead G201

[itsme]

Hi,

While using my machine today, the y-axis suddenly stopped working. On further investigation, I found that the 5A fuse to the y-axis G201 driver had blown. I replaced the fuse, but it blew again as soon as I turned on the power. Having read the FAQ in this forum, I measured the resistance between terminal 1 and terminals 3, 4, 5 and 6. Sure enough, the resistance between terminal 1 and 6, and also between terminal 2 and 6, is 0 ohms. This points towards a blown MOSFET, according to the FAQ.

I measured the voltage going to the G201s (three in total) in my enclosure, and it is sitting at 66V. The y-axis stepper motor is not at fault, as this still works fine when connected to one of the other two G201s. The other two G201s are still working fine (all three are wired the same with the same motors).

I have had the whole system up and running for about 2 months now, and up until today, everything was working flawlessly. As is so often the case, this couldn't have happened at a worse time, as not only has it written off about 4 hours of work, but it looks like it's going to put the machine out of action for a week or two - just when I really need it.

Now for the questions:

1) What is the typical procedure to have one of these things repaired? Although I've only been using them for about 2 months, they sat in a cupboard for about 2 years before this, so I guess my 1 year warranty is up (a little irritating...).

2) What typically causes one of these drives to fail? I'm reasonably confident that it is not the power supply or wiring. I'm a little concerned that one of the others may also go - not something I would have expected from these products (at least not before my y-axis failed). This problem can't be that uncommon, given that it appears in the FAQ.

Thanks in advance for any help
Warren

[CoAMarcus]

Warren,

I have attached our Stepper Return Form to this post. If you send the drive back to us we will evaluate it and repair it free of charge provided it is fixable. Generally speaking, if two MOSFETs are destroyed there may be damage to the PCB of the drive making it impossible to repair. Once we get the drive back we will evaluate it and go over what we can do from there.

Those problems are caused by a short circuit on the power supply pins on the drive or an over voltage condition. I have several questions:

What is the size of your filter capacitor?

What is your machine cutting?

What is your current set resistor value?

What is your motor's voltage, current and inductance rating?

Let me know the answer to these questions and we can see what cause this to happen.

Marcus

[itsme]

Hi Marcus,

The answers to your questions:

The filter capacitor is 100V 15000uF. The power supply is supplying 3 motors. Each drive also has a 100V 470uF capacitor at the power terminals.

The machine is a milling machine used mainly on cast iron, steel and aluminium. At the time of failure the y-axis was in motion, but the machine was not cutting (I was setting up a tool).

The current set resistors are 26.7 kohm.

The motors are 8-wire nema 23 wired in bipolar parallel. Ratings are as follows: 7.5V, 2.5A/phase, 10mH/phase. The exact motors can be found at:

http://arceurotrade.co.uk/Catalogue/...Stepper-Motors

Mine are the 220Ncm motors.

Regards
Warren

[CoAMarcus]

Warren,

Everything looks good in the setup; are your motor controls in an enclosure of some sort to protect them from metal chips? Typically with a metal cutting machine you will get chips in the drives which will short things out. Can you take pictures of the drive and the enclosure and post them up here? If not, then they will definitely have to come back here to figure out what happened and we will try to repair them.

Marcus

[itsme]

Hi Marcus,

I'm pleased my component choices have got your approval. I've tried to take some photos of the enclosure. Unfortunately, it's all a bit messy at the moment, because I've already disassembled half of it to get the drive out (which is on its way back to you now). I think you should be able to get an idea of what is going on though.

The drives are in a steel/aluminium enclosure along with the power supply and breakout board (the lid of the enclosure is balanced on top in one of the photos). This enclosure then lives in the cupboard underneath the mill (the cupboard does have a door, but it is not visible in the photo). The mill stand is sealed for coolant (although I haven't used coolant yet), and there is little chance of swarf getting all the way to the drives. In addition to this, when I took the drive out there was no sign of swarf inside the cupboard, let alone the electronics enclosure.

Regards
Warren

[itsme]

Hi Marcus,

I've sent you a couple of emails in the last few days, but haven't had a response. I'll assume they didn't get through for some reason.

I'm trying to determine if you've received my dead drive yet, as it should have been with you around a week ago. If you haven't received it yet, please let me know so that I can find out where it may have ended up. This is starting to get urgent now.

Thanks
Warren

[itsme]

Hi,

Just to fill in the gaps for anyone other than Marcus who is reading this, my G201 is truly dead. Phases D+ and D- are destroyed, so it is not fixable. Apparently, this is normally caused by a short on the motor wires. I have ordered a G201x to replace it.

I'm obviously going to have to put the new drive into my setup, and seeing that I'm still not 100% certain what caused the last drive to fail, I'm a little nervous to do this. I'm therefore going to give everything a thorough check over before I proceed, but I have a few questions. Which areas of the setup should I pay close attention to? Given the damage that the last drive suffered, is it safe to assume that the problem is/was on the output side of the drive (i.e. something to do with the motor and its wires)? Could a faulty motor winding or defective motor wiring cause this damage?

Although the motor still seems to be working just fine, I'm going to replace it just to be sure. What else should I check?

Warren

[itsme]

Hello again,

I received my new drive this morning - very fast considering it had to go halfway around the world.

I have another question to add to the list before I attempt ot use it. The G201x manual doesn't appear to mention the 'adjust' trimpot. Should I be using this trimpot in the same way as the G201's trimpot (to find a 'low' in the motor hum)?

Thanks
Warren

[itsme]

Anyone? I feel like I'm talking to myself here...

[CoAMarcus]

Warren,

It is functionally identical to the G201 trimpot.

Marcus

[itsme]

Hi,

After a good check over and reassembly, everything is working properly. I have 3 axes again, which is always nice. Although the y-axis stepper motor was stilll working and didn't have a short, I replaced it for peace of mind. Everything else seemed to be fine.

I'm still not sure why the last drive gave up. Let's just hope this one (and the others) keep behaving.

Thanks for the help, Marcus.

Regards
Warren