Help I'm melting!-Stepper driver connections.

Hi,

I'm new to the forum, and fairly new to CNC!

I work for a furniture design company based in south east London, and have been working as a Designer and general CNC guy for the past year and a half.

During my monthly maintenance this morning I noticed that a few connections one of the stepper drivers out feed to the motors looked as if they were getting hot and melting the connector slightly.
The machine is running smoothly but I would like to understand why this is happening to prevent any future damage to the machine.
Could this simply caused by dust sitting on the connections?
The machine uses Leadshine MD2278 Microstep Driver's

Thanks!

Jack :D



http://www.cnczone.com/forums/attach...d=381816&stc=1

More likely caused by a poor connection. Those connectors simply unplug. I'd replace them, and clean everything thoroughly with contact cleaner.

We refer to this as a "hot" connection. Like Gerry said....plus it could either be that the connections done with the screws were loose or the connection between the plug and socket is bad. I would cut off the heat damaged section of cable, replace the plug and inspect the socket pins on the pcb if they are damaged:)

You can take out that connector and solder it directly on the board itself to have the best contact compared to a new one, or you can change the two connectors (male and female) changing only the male means the female is already deteriorated and that means the new male connector will still melt some other time, your call :)

Ah great!

I will probably change both plugs, my soldering skills are pretty basic!

Thanks!

Gerry,

Can you recommend a brand of contact cleaner?

Thanks!

Jack

Basically, as it is already been said. What I'd do is that I'd disconnect everything, would remove the driver, inspect the insides. Perhaps you have a badly soldered connector. Check, clean, cut or replace the burned wire/cable and NOT just strip off the plastic, but crimp the ends. Do NOT solder. You will regret it if you solder it to the PCB and you should NOT solder the ends because that provides bad connections. Crimping is the way to do it.

the connectors have a history of failing on various devices
some times because cheap copies have been used !!!

the problem is compounded by the damage to the PCB mounted plug being damaged by the heat from a faulty cable connector
usually you can not get away with just replacing or cleaning the cable connector

the heat damages spring contacts & pins , resulting in increased contact resistance resulting in more heat !!!!!

you will need to replace the drivers PCB connector with a new connector or solder the wires directly to the PCB to use inline connectors to connect to the original wiring loom !!!

John

PS
see this post
Beware Melting Connectors on RAMPS boards | Model Engineer

PPS
another post gives these part numbers
Phoenix P/N 1935349;
DigiKey no. 277-1595-ND,
Mouser no. 651-1935349

note - these are PCB mounting screw terminals


search digikey.com for example for the original parts

https://www.digikey.com/products/en/...=0&pageSize=25

or farnell.com

http://uk.farnell.com/w/c/connectors...nix++connector

Apologies to sound so / be so newbish here ... but I cannot picture a "crimped" connection here for these connections. Do you perhaps have a picture of such a crimped connection you are referring to?

Thank you

Quote:

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Originally Posted by A_Camera

Basically, as it is already been said. What I'd do is that I'd disconnect everything, would remove the driver, inspect the insides. Perhaps you have a badly soldered connector. Check, clean, cut or replace the burned wire/cable and NOT just strip off the plastic, but crimp the ends. Do NOT solder. You will regret it if you solder it to the PCB and you should NOT solder the ends because that provides bad connections. Crimping is the way to do it.

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Quote:

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Originally Posted by MiniSoCalCNC

Apologies to sound so / be so newbish here ... but I cannot picture a "crimped" connection here for these connections. Do you perhaps have a picture of such a crimped connection you are referring to?

Thank you

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https://youtu.be/TZ01mezCWuE

Not my video but I crimp every multi core wire because that is the only way to make sure you get good and reliable connections in screw terminals. Very common and I think (at least in Europe) it is compulsory to use those in industrial applications. There are different crimp tools, the one in this video is just one of the many types.

I use that type of crimper and what I like about them is that they crimp all the way around. Ferrules into screw terminals are also a good choice.

Quote:

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Originally Posted by A_Camera

https://youtu.be/TZ01mezCWuE

Not my video but I crimp every multi core wire because that is the only way to make sure you get good and reliable connections in screw terminals. Very common and I think (at least in Europe) it is compulsory to use those in industrial applications. There are different crimp tools, the one in this video is just one of the many types.

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This is REALLY good advice. I use a different type of crip connection (one intended for a screw) only because I have a ton of them, but then I cut off the end and just use the part crimped to the wire. Other options which are NOT as good, but can work:
- A VERY quick drop of solder on the end of the wire. This is usually a really BAD idea because the solder will "wick" up the wire and destroy it's ability to flex in the part outside the terminal block. But, if you do it really quick with a really hot iron, you can avoid the wicking and still have a solid joint at the end. The other reason this is bad is that the soldered end will deform in the terminal block clamp, and loosen over time. You can avoid that issue by repeatedly re-tightening the screw until the solder has completely filled the terminal block clamp area. In the end, if it's done right, it works very well and is very reliable. It's just difficult to do right, and so not recommended.

- Really good quality terminal blocks with very carefully stripped wire. Again, works fine if it's done exactly right. What happens here is that the terminal block clamp area is corroded, dirty, or just not good quality or the wire is corroded, dirty, or too small, and so the contact has a high resistance. The other thing that goes wrong is that when you strip the wire, you nick one or more of the outside strands, and then as the wire is flexed that nick slowly breaks, creating a sharp edge that digs into the next strand and eventually the entire wire cracks off.

So I mention those two possibilities just to point out why crimping something on works better. It avoids stiffening the rest of the wire like the solder does, and the ferrule won't compress like solder. If you put the ferrule on with a bit of the insulation in one end, you are crimping over the start of the strip, so any nicks in the wire are held together and wont work loose. You can still have issues with corroded or dirty terminal blocks, but because the ferrule won't deform, it actually has a higher pressure at the points where it makes contact. It makes contact over less area, but better contact in the 2 to 4 places where it does touch. And that is actually better. In those places, there is a better chance of it cutting through the corrosion or dirt.

And that turned into a book. Sorry. Hope it helps explain WHY crimping a ferrule on is best.

We even have this problem on our Bosch servo drives.....i usually repair a dozen or so each year. However we usually identify any issue before damage to cables occur.

http://www.cnczone.com/forums/attach...d=383268&stc=1http://www.cnczone.com/forums/attach...d=383270&stc=1