Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: james elder on September 05, 2013, 05:47:54 PM
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Hi guys, snazzy website now...
Not exactly Mach 3 related, as I have had many years of trouble free use, but you guys have helped me before, so here goes:
Jogging along the x axis, unusually some stuttering, then a 'POP' from the region of the electronics, and no x axis movement.
So i have a look. No light on one Gecko 201. Ah, must be the Gecko? Put a spare Gecko on the connections, still no light. Check the spare Gecko on the same connections as the lit Gecko on Y axis. Lights up. Must be the connections therefore to the x axis Gecko. Put the X Axis connections on the Y axis Gecko 'POP' and no light on the Y axis Gecko either now, although I don't suspect the Gecko's, as they worked on different connections after the POP.
Is this enough info for you guys to tell me what I need at least two new ones of? :-\
James E
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I'd guess the x-axis stepper wiring or stepper motor itself has a problem.
If the motor output from the Gecko goes open circuit while powered up, then chances are the drive will go pop. I'm not sure if a short ciruit would do the same, or if the current limiting would cut in before any problems occur.
It could be that when you've tried the spare gecko, the wiring/stepper fault has been present causing the drive to stay in fault, then when you've swapped the Y-axis drive across, the wiring/stepper has gone from good to bad and it's gone pop.
I'd check over the stepper wiring very carefully for any obvious faults, and if no obvious faults can be found, replace the wiring and possibly the stepper motor (consider how the cost of a new stepper stacks up against the cost of another trashed 201...)
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Thanks for reply
I am not sure I understand, the gecko on the 'pop' x axis still worked (or at least lit up) when put on the non faulty y axis wiring, it was putting the presumably faulty x axis wiring on the y axis gecko that caused the second pop.
However, it has got to be right that should check all the wiring, and I will, although looking at one of my x axis rails, clogged with sawdust, could the machine stalling the motor cause this?
Is one way to go get some readings off the wiring into the Gecko that still works and compare with the other two sets of connections that now don't?
jim
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A long time ago when I got some G202's(?) I had a similar issue, a loud pop or whatever, turned out it was the blue plug that was the problem, I know of someone else who also got that problem. I thought with the noise that the drive had to be dead but it wasnt and I think it must have just been the big cap discharging/shorting.
Maybe not related to your problem but .... well you never know.
Hood
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Yes, I have had a problem with the blue caps before, which is why I have a spare drive now. Thanks for the suggestion, I will investigate that.
Jim
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I have to say I could not find a problem with the connector at all and neither could the other guy but it would happen every so often but after replacing with a different plug it never happened again.
Hood
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Noted
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Well, I have refreshed the connections, but i have found that, whereas I can get continuity from the capacitor to the z axis power in on the Gecko, I can't get it to the x or y axis Gecko, even though it appears to be just a straight cable. I am reluctant to just change the cable in case it is a symptom of the problem, not the cause.
Any ideas?
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Probably best to ask advice from Gecko, they will know what to check :)
Hood
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Well, they have offered to check the Gecko, although they have instructions for testing on the website under FAQ's
I have now dissasembled the machine, and found three fuses in the power supply to the geckos. whoopee. 10 amp.
So, would a tight machine stalling a motor cause this fuse to pop?
jim
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Sorry dont know enough about stepper to say :(
Hood
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Jim,
So, would a tight machine stalling a motor cause this fuse to pop?
The G201's are limited to 7 amps, the drive amp setting is determnined by the size of the resistor on the drive connections.
I use a switch array which allows selection of different drive resistor values such that different stepper motors can be used.
I use quick blow fuses to limit the amperage available to the drive and they are not above the rating of the drive.
Let me also add that you should have a cap on each the the axis connections for the G201's. The newer drives have the cap built in.
So read your drive instructions.
The info on Gecko site is a simple test for testing the drive and if it dosen't pass the test then the drive is blown and not repairable.
In general, when a motor is stalled the current goes to infinity and would burn it up as all the energy is going to heat.
So when a stepper stalls max available current is delivered, in your case 10 amps +- ........... depends on the fuse on when it will actual blow.
You provide a desired voltage and protect / limit the available current to the drive to protect motor. READ THE MANUAL!
Blow a drive and you are forgiven. Blow another drive and you deserve to pay the price! ;)
RICH
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In general, when a motor is stalled the current goes to infinity and would burn it up as all the energy is going to heat.
So when a stepper stalls max available current is delivered, in your case 10 amps +- ........... depends on the fuse on when it will actual blow.
That is not true at all. If the motor stalls, current will, eventually, reach the maximum value allowed by the current limit resistors on the Gecko. The Gecko will never allow the current to exceed this value, unless the Gecko is a;ready damaged and no longer working correctly. Even in that case, the current NEVER "goes to inifinity'". The motor windings have resistance, which also limits the maximum current the motor can draw. You can lock the rotor on the motor for as long as you like, and there will be no damage whatsoever to the motor or the Gecko. The fuses only protect the motor, and wiring, from over-heating in the case of a Gecko failure, a wiring short, or other failure.
Regards,
Ray L.
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Ray,
Thanks for the clarifications. I'll try better wording next time. ;)
RICH
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Well, thanks for the input guys, I did find three hidden 10 amp fuses, two blown, and one by one replaced them. Now I have three lights on the three Geckos.
jogging on two axes, great. jogging on the third, the x, grumbling movement, even with nothing on the motor. Swapping the Gecko's, and the problem goes with it.
So there is a fault on the Gecko 201, and maybe the stiff axis stressed it to failure.
I have never looked at the manual till recently Rich, the Gecko's were on the machine when I got it, and apart from a similar incident in 2007, no problems.
Jim
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Jim,
What is the amp setting on the drive for the X axis?
Is the X motor the same as the other two?
Can you better describe other than "grumbling?
RICH
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Well Rich thanks for the interest,
all three steppers are the same, and it's all been running well for a few years now.
The grumbling noise, well the others wizz along nice constant high pitched wheeeee. The one with the faulty driver, that's what I am assuming, as the problem moves with it, goes err. errerr eererr. wheeee errerr. errerrerr wheeee err. err. err. Random roughness, stuttering, stopping and starting very quickly... swap the driver and wheeeeeee.
The drives were nicely heatsunk, and only ever got tepid to the touch, if that's any use.
Amp setting for the drive? don't know. :-[ Where would I find that?
Jim
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The grumbling noise, well the others wizz along nice constant high pitched wheeeee. The one with the faulty driver, that's what I am assuming, as the problem moves with it, goes err. errerr eererr. wheeee errerr. errerrerr wheeee err. err. err. Random roughness, stuttering, stopping and starting very quickly... swap the driver and wheeeeeee.
Tempted to suggest one axis may need cleaning, and one phase in the driver has been cooked. Simplest test is to drop a new driver in; even cheaper is to swap one of the other drivers in temporarily.
The X axis can often pick up dirt which then clags the balls in the ball nut. Cleaning all that out is an exercise for a masochist, but it can be done. (Been there, done that.)
Cheers
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Hi rcaffin, yes, I have swapped the drive and the problem migrated with it. Interestingly whoever made the machine seemed to want it to work as if by magic, all the threads are hidden inside aluminium box section, but at the time there was some build up on a rail on the x.
New Gecko is on it's way at the moment, fingers crossed. Thanks for the interesst.
Jim
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The G201 amp setting is accomplished by placing a resistor across two terminals of the drive.
READ THE MANUAL since it shows how to calculate the resistor size. Obviously you have not installed the capactor on the
drive as I noted before.
RICH
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In my investigation I tested those items, and since they all redid almost the same, I assume. They are all ok. I have glanced at the manual now, enough to realise why the fuses were hidden. Because there is a short recommended length between capacitor and gecko, there was a routing problem that lead to the fuses being hidden.
Bear in mind this is not a new build, no I haven't thoroughly examined the manual. At the time of the original post, I had no idea what the fault might be. You guys have helped me decide it is probably the driver, possibly failed to to binding shaft.
Jim
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redid almost the same, I assume. They are all ok.
that spellchecker! and me with no specs. Read almost the same so I assumed they are all OK.
Looking at my new 201x, there are option switches, which are related to the motor type the manual says.
3.) NEMA-34 and NEMA-42 Motor
Use this option if the drive is to be used with NEMA-34 and NEMA-42 size motors. This option adjusts the midband compensation circuit for optimum performance when using a NEMA-34 and NEMA-42 motors. SW10 enables this function when “OFF” and disables this function when “ON”. SW10 should be “ON” when used with NEMA-17 and NEMA-23 motors.
I simply don't know what type of motor I have, and whether they are NEMA-34 size or what.
Any info gladly received.
Jim
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I would say most likely you have Nema 34 or smaller. Here is a link to show the sizes.
http://www.tinycontrols.com/stepper-motor-sizing-tourque.html
Hood
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Thanks. Thought it was something like that but did,nt want to guess. The clue is in the name 4.2=42... I,ll go and measure. Thanks.jim
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34's then, and using a resistor, so 1-5 on 9 on 10 off.
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Sorted. Thanks guys