Help with Problem X axis Stepper Please

[howser37]

Thanks Graeme. Much apreciated. I read a few things about the mica washers not being as effective at getting the heat into the sink, hence the idea of just having the thermal compound. But you are right i will not start messing with things like the grounding in a system that i already dont trust lol. Thanks for the info on testing the wires, im pretty good with mechanical things but electronics baffles me at the moment.

Hi Robin, thanks for the input. You know now that you say it i dont know why this didnt occur to me that this looked like a previous repair. But it does look like a soldered over track and the solder gas blown, but again i guess its back to what caused the first failure.

Anyway i will report back what happens

[howser37]

Hi guys just a quick update and a query, i have cut away the broken track as suggested and eventually after a bit of trial and error have managed to solder a jumper nicely to the right terminals on the back of the pcb, quite a task as the pins are very close together :-o. replaced the IC chip and also upgraded the cooling by having a much beefier fan suspended from the top of the contol box onto the Driver chips and heatsink while i was at it.

I am now checking the wiring on the suspect X axis motor, i have attached a picture to show what i am dealing with, i want access to these termianals but they are burried inside these 3M terminal blocks, i popped one out and the brown driver wire literally just fell off whereas the other two needed a bit of removal force, so i guess even that brown wire could be a potential short. To be honest im not too impressed with these 3M terminals, they seem a bit fiddly and precarious, what kind of terminal are you guys using for this, wouldnt something i can get a tester on at a later date without having to rip the thing apart be more suitable ?. Id like to remove them all to test the cable and replace them with something a bit less permanent and more robust if possible

[GND]

Not sure the picture got attached. Interested to see what you're dealing with before offering suggestions.....

[howser37]

Hi Graeme i have attached it now, i believe they are grease filled scotchlock terminals, maybe they are good they just seem a bit awkward and open to failure to me and difficult to get apart without potentialy damaging the connections.

[GND]

They look like some kind of one-time crimped connections, which are highly protected against shorts and therefore also restricting access to the signals for testing. Probably a good choice for the job, but definitely not very serviceable! I'm sure someone else on the forum will have a proper name for them....

I use good old fashioned chocolate blocks for my connections. They have their flaws, but they are cheap and easy to use - and probe-able for testing! You could always start with them and see how t goes, at least to get back up and running?

Cheers
Graeme

[howser37]

Hi Graeme, i have some chock block connections here so i will give them a try for now and see how i get on. I can see how the current connections are highly protected against a short but im wondering about a break as i highly suspect that brown motor wire was not connected well, and i know that these drivers cannot be hot unplugged without blowing the drivers as there is no protection, and ive heard many stories of people unplugging the cables whils energised and blowing the drivers, i wonder if a poor or nearly broken connection here could intermittently simulate a similar event.

[GND]

Well, it's certainly one possibility! Crimped connections are great when they work, but can fail without it being obvious to look at. If that brown wire came out without much effort, then it suggests it wasn't right.

Looks to me like you have those motors wires in parallel, as there are four connections with two motor wires to each. Disconnecting one winding would have reduced the current on that phase, but would also imbalance the load on the chip. Quite what effect that would have is beyond my experience, but who knows. Certainly something to fix though!