[wildwhl]

Series 3 1100.

During second operation of the day (simple peck drill cycle) Z axis went caput. Note the burned leads at the driver from the stepper (2 of 3 leads). Driver continues to have red fault LED, even after stepper is disconnected. Likely just as toasty inside as it is at the connector.

So, my question for you folks because I had to leave and play dad. When I get back here in the morning, can I verify the stepper is okay too, without risking blowing another driver? Between the 3 leads resistance measures between .8 and 1.0 ohms.

Thanks for all help, and advice in advance.

WW

[SCzEngrgGroup]

It is extremely unlikely the motor itself is damaged. The burned connector is an indication of bad connections AT the connector. This causes heat, which causes the melted plastic. The motor is unlikely to die, other than from over-heating due to an extended period of running at continuous high current. As the connector was almost certainly the cause of the failure, even the driver is, more likely than not, still ok.

Regards,
Ray L.

[wildwhl]

Thank you Ray. Actually had just a few minutes before I have to go, so popped the driver out to have a look. Got brave and tested motor on the X driver and it is fine, as you suspected.

Here's pics inside the (failed?) driver...definitely smokey. I see evidence of a very tiny shard of aluminum at the connectors - as in a short caused by debris. I even have a thought as to how this may have made it's way inside the cabinet but will have to investigate further to be sure.

WW

[SCzEngrgGroup]

I don't see any obvious damage there, other than the damaged connector. All the residue appears to me to be the common flux residue from modern "no-clean" soldering fluxes. I would not be surprised to find the solder around the cooked connector pins has flowed. Of course, if the connector on the PCB is damaged, that pretty much scraps the whole drive, since you'd have a hard time finding a replacement connector in qty. 1.

Regards,
Ray L.

[eltejano]

Intermittent or a loose connection with a current is a recipe for failure. If the connector is loose and only making contact on a little spot, the resistance goes up significantly. Like using a tiny hair width wire where a large cable is needed. But, unlike the small wire or like a low voltage fuse where the connection melts away, the large connectors simply heat up because they have a lot of mass. Eventually this will happen. Same happened on the Tormach I was using at the card on the controller. It was loose and it fried the connector.

[wildwhl]

Looking back at my notes - the symptoms I had today before failure had occurred at least once before. While I have checked those connections recently (where the screws clamp the wire) I have no real way of checking/correcting the friction fit of the pins, short of kinking each pin (a trick I've used in other instances like this). What I had thought was an aluminum fragment that possibly caused a short is in fact a mis-diagnosis. This is why I have glasses, and should where them when troubleshooting.

I have another driver inbound and will attempt to make this one function again as well.

Thanks for the feedback.

WW

[CitizenOfDreams]

Of course, if the connector on the PCB is damaged, that pretty much scraps the whole drive, since you'd have a hard time finding a replacement connector in qty. 1.

Actually, those are common-as-dirt Phoenix plug-in terminal strips. Retail prices start at less than $1 for a quantity of one at DigiKey. Of course you would still have to pay for the shipping, but it's still worth it.

But first I would check the output transistors and other components. They could be fried as well, even if they look OK.

[adamvs]

CoD, that's good to know. I've had this happen twice and found a close enuf part on Mouser. The cause? Putting bare wires into the terminal block. I believe current flow causes oxidation over time, which leads to higher resistance, which spirals into melt down. In both cases I took these to a local electronics guy, who happens to repair Fender tube amplifiers. What's important is to use high temperature solder to install the new terminal block. The repair worked 100%, there was no damage to the circuitry. Motor wires now have a crimp sleeve over the ends, and haven't had a problem since.

[wildwhl]

Actually, those are common-as-dirt Phoenix plug-in terminal strips. Retail prices start at less than $1 for a quantity of one at DigiKey. Of course you would still have to pay for the shipping, but it's still worth it.

But first I would check the output transistors and other components. They could be fried as well, even if they look OK.

Didn't have to look long to find damaged components. Board is toast and a replacement is on the way (I should say ordered, no idea when Tormach will actually ship). Good time to catch up on some other projects and maintenance.

Thanks for all the feedback.

WW