Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: james elder on May 14, 2014, 03:57:23 PM
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Good to see you guys.
Briefly, after swapping some bearings, my x axis only made a quiet whine, and no movement. Checking I found about 4 wires had come loose from the choc block connector to the motor. Putting them back in, one touched the framework and I realised i had left it energised when there was a crack crack from the direction of the control box.
Checked the fuses, :( They were ok. Swapped the Gecko's about to see if one of them was the problem. Crack. Magic smoke from the good Gecko moved to the X axis. So now I am 2 Geckos down, call it £250 on the night, and don't know what the problem is or how to track it down. Suggestions please?
And it's always when there's a big rush on, and also, I can't seem to think straight, or I would have tested the suspect drive Gecko on another axis...I think it's panic.
suggestions welcome.
james
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Ohm out your motor windings to see if there is a short.
Hood
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Thanks Hood.
I did continuity, if that isn't enough I can ohm, but ;
8 separate wires,
Continuity between
ORange / orange and white
Black / black and white
Yellow/yellow and white/red/red and white.
couldn't compare with other axis, the 8 are wired in pairs on that.
any clues?
jim
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You would need to Ohm it as all continuity will tell you is that there is a connection. It could be a dead short and you would get continuity.
Hood
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Ok. :)
Y to Y/W =1ohm
Y to R =1
Y to R/W =1
Y to O/W = 1
B to B/W =1.3
R to R/W = 1.3
O to OW = 1.3
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Its been a long time since I looked at steppers but an 8 wire motor should have 4 separate coils I would think.
If the above readings are with the wires separate then I would say you have shorts, if you still have the wires connected (parallel or series) then you need to separate and test between coils and also you can test between one coil and another to make sure there is no continuity.
Hood
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They are all separate, so is is significant that there is continuity between the colour pairs, ie red/red and white, but then there is continuity between two of theses pairs...
thanks for the help by the way.
jim
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Looking at the Gecko guide to steppers, there is no layout that can give continuity over 2 pairs in an 8 wire setup, so it looks like the stepper is junk.
Can I just swap it for new, replace the Gecko's and I am good to go, or is there something else I should check? Very nervous about the magic smoke.
jim
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There should not be continuity between coils as they should be separate, so as said above I think your motor is fried.
It is most likely a new motor and drive will be all that you need to get but do check all connections and the voltage of your PSU before you hook things up.
Hood
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Will do, thanks again.
jim
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Anyone suggest a replacement for a HY - 200 -3437 - 460 A 8?
There are some used available, but not in the uk, so not readily available.
jim
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HY - 200 -3437 - 400 A 8 actually I think.
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You need to know the spec's for your stepper motor and then just look around for one that is as good or better.
These days you can buy a new stepper rather cheap so maybe skip the used stuff.
I would suggest that you go to the Geco site. They have info on how to properly test their drive to see if it's blown.
Never plug or unplug a stepper when it's powered, or take readings on the wires when powered.
Also have a look at the different wiring configurations. Don't assume that color coding is correct, thus check continuity to confirm . Cross sheck the leads to the coil windings to make sure there is no shorting.
If you don't know what your doing stop.....stop what your doing.
Stopping is way cheaper than blowing a drive or doing damage.
RICH
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Thanks, Rich, I think I'll print this out and staple it to myself.
I have taken advice from cnc4u, who have a motor just for the job of replacing these, and on is on it's way. There's also two gecko's and a rabbits foot on its way, but i confess to some anxiety. Thanks for the help.
jim
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Can I borrow the rabbits foot when you are through? We have all been there or a place like it. You are not alone. Is there an intermediate harness? Are you testing the steppers right at the stepper itself or at the end of a long wire/bundle? Any connectors inline?
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im not interested in what youre doing to these geckos...im interested in what your doing to afford all these replacement geckos!
erm. as mentioned, sounds like the motors junk. get a new one. im happy with my chinese rubbish still :)
real grey smoke? that smells funny?
you arent just popping the internal fuse that you wouldnt suspect of being a fuse until you do a thorough check on the manual and the smoke is just descriptive language?
i didnt note which gecko you actually have, but as far as im aware the multi axis jobs are modular.... i could be utterly wrong, so dont quote me... pretty sure i can pop out each axis from the main BOB when i pop the covers... which was a long time ago ;)
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Hi HeadSmess,
I can't afford these Gecko's, hence the anxiety I mention. Well, not as a method of testing the motor anyway!
A new motor is in my posession, smaller and lighter than the original, as Rich suggested. This opens up possibilities for when there isnt' a rush on; I could swap the big one from the Z for this lighter one. There isn't much triangulation on the Z, and the weight of the motor at the top makes it pendulum a bit.
I was fooled last time when I eventually found some hidden fuses. this time I saw half a cup of grey smoke and heard two cracks. The first I didn't see, but I heard it, and, I am testing right at the motor. 8 wires 100mm long, straight in. Two phases are connected that shouldn't be. 201's
Right at the stepper Fastest1. There isn't much hope for it I'm afraid. The replacement cost less than the Gecko so...
Thanks for the replys guys. There's something heartening about communications from other members.
Jim
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To know you werent the only one to screw up? That does help. Dont worry for years I was sure that the Youtube machining Gods used different vises and fixtures for their videos, just because they always looked new and unscathed. Who hasnt inadvertently drilled or milled a hole into a vise, clamp or the bed of the machine for that matter?
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Who hasnt inadvertently drilled or milled a hole into a vise, clamp or the bed of the machine for that matter?
Me, but i will admit that hopefully it will never happen, but I am assuming that i also have a lot of time to go and only time will tell. :D
RICH
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As with other things, one disturbance telegraphs down through through time magnifying as it goes. This all started with a Kress safety feature. When the brushes are halfway worn, there is a spring inside that pops out and that,s it. Stopped dead. 10mm in the wood. it saves the kress armature!
Jim
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Ok.
Z movement, hurray, with new gecko, the old one was foolishly sacrificed
X movement, hurray, new gecko, and new motor.
Y noise but no movement. a sweet whine, responds to the keys. This has had no parts but did bind at the end of the last session, when it made a noise like a toothed belt slipping, which is what it drives.
What could hve affected this axis, or what does the noise suggest?
Thanks for replys
Jim
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and the stepper is singing quietly when it is idle. very high whistle.
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There's only continuity in the phases, and none where there shouldn't be, and 3 phases settle at 1.3 Ohms one at 1.2.
Now I have taken the belts off, I can see the spindle is stuttering, doing maybe 1/4 turn, sticking, vibrating etc.
Does this point to any suspects?
Oh, the gecko tests ok, and remade all the contacts on it with new blocks.
Jim
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Blow a drive and you are forgiven. Blow another drive and you deserve to pay the price! Wink
RICH
How prophetic, that was you to me last september Rich.
Searching the forum it's the Gecko isn't it.
I'll swap them in the am and see if the fault migrates, since it isn't a Deadly fault
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is the y stepper working when not attempting to drive anything?
sounds like a step pulse issue. id start at the default 2 and fiddle from there. step direction and pulse possibly, but nah...one would make it go backwards, and one would make it spin UNTIL you tried jogging, which would stop it...
and try the x axis from the y driver, etc, etc :)
tis why i have a large box of various steppers lying around. nema 17s are cheap enough to sacrifice when required! ie, free from the scrapyard :)
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No, juddering and stuttering, not turning. I will swap the drives shortly.
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Try swapping round the pin assignment if Mach for the Step and Dir signals for that axis, or you could alternatively swap the physical wires.
Hood
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new lead from NON to PC.
non? i still type by sight and the white out on half my keys from some program that made it into a piano doesnt help...
BOB to PC...
BOB itself... i still couldnt be bothered backtracking and seeing if you mentioned what breed, what species of gecko you have...
intergral BOB or separate?
and finally, what happens if you hook the lot up to the other PC you have that also has mach3 installed? just incase its your motherboard?
just ideas...if swapping doesnt help, etc etc...
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Hi Guys, greatful for the follow up suggestions.
An update. I contacted a local guy who saw my cnc machine years ago and went away and built himself one, then another, and another, to see if he had any bits, because even if it is my gecko, I would have had to wait two days to get a new one, and then, who knows? and I have the customer waiting,,, Unbelievably the guy lent me his machine. Its in the workshop now wizzing away. My priority is getting the job done before I try repairing mine.
At which point I will swap the Geckos, which is ok this time because the fault isn't a gecko fatal one. In other words, if the Gecko blows, don't put another one on :-[ If the motor stutters, swap the geckos and track the fault.
jim