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Greg J Tue 28 August 2007 11:37


I'm going to swap out the drivers one more time to make sure. I believe Gecko when they say the driver is good (maybe a fault on my part). I will exhaust all causes ( and document) on my end before I resend the driver to Gecko.


My Mach3 Config is the same. I will check resistance. Thanks for the offer of help. Gerald and yourself have been a great help and its my responsibility to use all my troubleshooting abilities before I waste your time. If I run into a brick wall by ... oh ... Thurs/Fri, I'll call for help.

Thanks again guys,

Gerald D Tue 28 August 2007 12:35

Greg, with 4 positions on the BOB, 4 drives, 4 sets of drive connectors, 4 sets of wires, 4 motors loose on a bench, and 3 of everything works okay, then you swap, swap, swap till you find the culprit. Just remember to switch off till the Gecko LED's die completely before doing any swopping.

Art Sun 18 November 2007 20:27

Gecko warning
With my indexer I was having problems with the A (rotation) axis moving. Fix was to disable automatic voltage reduction. Automatic voltage reduction occurs 1 second after the last motor movement and reduces the power to the stepper by 30% to 50%. Problem was apparently fixed with the automatic voltage reduction disabled on the Gecko 202. However about 30 days later another problem emerged. After few minutes or a few hours the Gecko dropped ALL power to the motor. I will skip all the trials and tribulations and give you the short story. In 3 days on the Gecko news group there were 4 others who reported the same problem and all were with larger steppers and Gecko refuses to even discuss the problem. The 203 is not a solution because the automatic voltage reduction cannot be disabled. I have installed a Chinese drive and I will update when I am sure of the results. The thing about this whole epasode is Gecko's apparent refusal to acknowledge/resolve the problem with one of it's products. Doesen't give me a comfortable feeling using their other products.

Gerald D Sun 18 November 2007 23:36

Art, I have been watching those reports, and with all due respects, they are poor reports being light on facts regarding the cooling of the Geckodrives. Can you give us a photo of how your drives are mounted, details of the heatsink, thermal grease, the control box volume, the fan and the filter (if applicable)?

Gerald D Sun 18 November 2007 23:41

Mariss did reply this morning:

The biggest drawback of a G202 is the lack of a short-circuit
indicator LED. What you call "a well known problem" is actually the
drive tripping its short-circuit protection latch. This happens with
old, partially demagnetized motors whose inductance has dropped and
some Chinese motors whose windings arc internally at elevated
temperatures when driven at high supply voltages.

Since you are dissatisfied with the G202s, you are kindly encouraged
to return them for a full refund. I'm not trying to change your mind
and I wish you the best with your new drives but I'd like to correct a
few things:

1) The G202 doesn't have temperature protection, only short-circuit
protection. Drives and motors warm up at the same time. As motors warm
up, they expand. If the motor wire insulation is compromised, internal
arcing happens while it's warm, not cold.

2) No drive has "voltage reduction". Some drives have "current
reduction". The G202 and G203 have current reduction.

hflwaterski Mon 19 November 2007 11:55

What does this mean for G203V?
I haven't gotten into the details of wiring the panel yet. I just ordered 4 Gecko G203V drives :eek: and I guess I'm trying to get my head around what exactly your saying about these drives. Both the enclosure and the drives should arrive today or tomorrow. Does this all mean that I shouldn't have bought these drives :confused: or am I OK:D. I'm planning on finishing the kitchen table project this winter and the metal fabrication and paint this spring. I expect to be done by late spring or in the summer with the MechMate Mamba project.


Gerald D Mon 19 November 2007 11:59

Herb, what motors are you planning to drive? If you stick with the Oriental Motors suggested here, you will be 100%.

hflwaterski Mon 19 November 2007 12:59

Oriental Motors

Yes, I plan to stick with the Oriental Motors. Thanks for the info. I'm going to get nervous about all my purchases until I see this thing start throwing chips.


Richards Mon 19 November 2007 13:26

I've logged thousands of hours with Gecko G202 stepper drivers and Oriental Motor stepper motors. I've also logged well over 1,000 hours with Gecko G203v stepper drivers and Oriental Motor stepper motors. So far, there has been NO problem of any kind. And, may I also add, my test bench time with the motors and drivers would have to be considered harsh time. Usually, I'm on a quest to see just how fast I can spin the motors, or how high I can run the Voltage of how long I can slowly toggle steps back and forth to get maximum heat out of a motor and driver.

Recently, I bought back four Oriental Motor PK268-02AA drives that I installed years and years ago when that model motor first came to the market. Those motoors were in use five days a week, eight hours a day, cycling once every second for well over a decade. During their service life none of the drives failed (or even failed to perform as expected). On the test bench, they perform exactly like four brand-new, just out-of-the-box motors. They have the same torque and the same speed.

As far as Gecko products go, I've never had any kind of problem or concern with anything. Mariss and I have talked on the telephone twice. Both times I called to get some very simple assistance. Both times Mariss personally answered the telephone and spent as much time as I needed to teach me how to better use his product (and while doing that, to teach me more about stepper motors than I thought any one person could know).

One last point: I have never been a fan of using stepper drives or stepper motors of unknown or unproven quality. The stepper motors and stepper drives are the very heart of a CNC machine. Does it make any sense to carefully follow Gerald's plans to build a robust and elegant machine - and then slap on bargain basement stepper motors? You only pay for quality once. Junk is a continual drain on the wallet.

Edited: Mariss has continually cautioned us against using extra large motors. In some of his literature, he recommends that the size 34 motor as being the best size partly because it has enough mass to radiate heat away from the motor. (Smaller motors like the size 23 PK268 motors get hot and stay hot because of their small size.) I've found that the PK29x size motor from Oriental Motor works very well. Models are available handling torque ranges from 300 oz*in to 880 oz*in. The PK299-F4.5 motor, at 880 oz*in Bipolar Parallel, is the largest motor that I will use. Other, larger motors are available, but I just can't see the need of using larger and slower motors on a CNC machine when a smaller motor can be geared to outperform the larger motors.

J.R. Hatcher Fri 04 January 2008 05:55

Quote by Mike; "You only pay for quality once. Junk is a continual drain on the wallet".

Quote by unknown; "The bitterness of poor quality lingers long after the sweetness of cheap price has gone"

Oh... while we are on the subject if anyone would like to buy some cheap drivers I have a rather large collections (26):o I obtained before I decided to go with Geckos. Ditto the motors too before I bought the PK296 & PK299 series.

Where were you Mike Richards 2 years ago when I needed your expert advice???;)

All joking aside thanks for your willingness to share that knowledge base now!!!!!!!

sailfl Fri 04 January 2008 05:58


EBay and CNCZone. There are plenty of people on CNCZone looking for drives and motors. Many use motors out of Photocopy machines. I think you will find lots of buyers there.

J.R. Hatcher Fri 04 January 2008 06:11

Thanks Nils, however I was joking about selling them to you guys. But now that you mention it maybe I should sell them on ebay, trust me I got plenty of other stuff that will catch the dust.:D:D

J.R. Hatcher Fri 18 January 2008 06:39

Mike my motors PK299-01AA are pulling 2 amps. You said the resistor for the gecko 203 drives needed to be 18k to 20k. I have a bunch of 22k I think this would give 2.2 amps, will this be ok?

Richards Fri 18 January 2008 09:02

22K should work okay. That allows about 11% more current to be pulled through the motors, which should not be a problem. If the motors run hotter than you would like, then try a lower value resistor. (The resistors only cost about 15 cents each.)

Excessive heat can also be caused by high voltage, but that should not be a problem with PK299-01AA motors because even at 80VDC (Gecko maximum voltage) with the motors connected half-coil, you would only be using 70% of the voltage that the motors could handle.

Gerald D Fri 18 January 2008 09:03

JR, if you put 100k to 220k in parallel over 22k, you end up with 18k to 20k. Food for thought. (Personally I would use the 22k's, check for heat, find none, and forget to get the "correct" one :))

Gerald D Fri 18 January 2008 09:04


domino11 Fri 18 January 2008 09:51

If you need an assortment of resistors let me know and I will mail you a kit of what you need. I have tons of them. :) And I send mail to the US all the time. No trouble.

Doug_Ford Wed 23 January 2008 12:42

When I cut air (the router is turned off), the motors sound like they are playing a musical tune. It isn't loud and doesn't bother me but I'm wondering if that's normal. Do you think I need to tune them? The instructions for tuning the motors are somewhat imprecise so I thought I would ask the question.

Gerald D Wed 23 January 2008 13:14

Playing tunes is normal - those are the step frequencies making those "notes". Some people have even written air-cut programs that play recognisable tunes.

Tuning the drives is important, and easy. The instruction says:
"Set the motor speed to about 1/2 revolution per second and then turn the trimpot until a distinct null is noted in the motorís vibration" . . . .

Drop motor away from rack, set a move speed where the MOTOR takes 2 seconds to make a full turn. With a 7.2 gearbox, it must take 14 seconds for the pinon gear to make a full turn. (This need not be precise - it just indicates very low speed)

While holding one hand on the motor, tune the drive until the motor feels at its smoothest. There is a distinct smooth spot and it is easy to feel it.

Doug_Ford Wed 23 January 2008 17:59

Thanks Gerald!

revved_up Sun 20 April 2008 18:32

What is the difference between carbon film and metal film resistors and which would be the choice for the geckos?

domino11 Sun 20 April 2008 18:39

Carbon film resistors are really old technology. These days metal film resistors are the way to go. Early in the day, carbon comp resistors were cheaper to make and therefore for non critical applications they made sense. These days metal film resistors offer better performance in tolerance, temperature and drift and they are affordable. Use them if you can.

Greg J Wed 04 June 2008 17:29

Everything on my MM seems to be operating just fine.

But, one of the Gecko V203's has no green light. When power is first applied to the control box, I get a red and yellow light on the drive. The three other drives have a green light.

This happened during the kitchen project, so I sent the drive off for inspection. Gecko said everything was fine.

Just thought I'd mention this. Maybe just a failed light bulb.

Richards Thu 05 June 2008 03:26


If you only got a Red light, then I would agree that the Green side of the L.E.D. was not working; however, to get the Yellow light, both the Red side and the Green side of the L.E.D. have to be on at the same time.]

According to the spec sheet, the G203v should have the Red L.E.D. on when the G203v is first turned on (1 sec), when the G203v overheats, when the Disable input is active, or when there is a short circuit present. The Yellow L.E.D. turns on when the drive is running at full power. Otherwise the Green L.E.D. should be on at all times.

However, if the G203v is driving the stepper motor properly, then having the Green L.E.D. on or off really doesn't matter.

By the way, does the Green L.E.D. come on when you ONLY have power supplied to the G203v? (No motor connections. No step/direction/common connections. No resistor connections.)

Greg J Thu 05 June 2008 22:14


First, thanks for the help.

I re-checked it this evening. I was in error before. I get a red LED on all four drives when first powered up. No yellow LED is ever present. I was working from memory in the previous post (I should know better :o)

After the red LED, 3 of the 4 drivers go green, and the fourth, shows nothing.

Just to re-iterate, everything seems to be operating fine. I have not cut anything yet, so the motors/drives have not been under much of a load.

Gerald D Fri 06 June 2008 00:14

Originally Posted by Greg J View Post
I have not cut anything yet, so the motors/drives have not been under much of a load.
The weird thing with stepper motors is that their heaviest load (electrically speaking) is when they are idle. Get them to do some real work and then they get cooler!

Greg J Fri 06 June 2008 07:05

Originally Posted by Gerald D View Post
The weird thing with stepper motors is that their heaviest load (electrically speaking) is when they are idle. Get them to do some real work and then they get cooler!


Back to the Gecko documentation on "basics of stepper motors".

domino11 Fri 06 June 2008 09:20

Another site to check for info on stepper motors and drivers is There is a lot of good reading there. :)
Actually, he references geckodrives article as well! :eek:

Greg J Fri 06 June 2008 09:21

thanks Heath.

edrowell Mon 09 June 2008 20:12

Originally Posted by Richards View Post
The L.E.D.s for pins 3,5,7,9 may be ON or OFF depending on the status of the step pulse, but those L.E.D.s should flicker ON/OFF when the motors are turning.
I'm having some issues with my setup as well. I have one PK296A1A-SG7.2 (half-coil), two compumotor LN series motors (full coil), three g203v drivers, and one pmdx-122. I got everything powered up and was even able to get some motor movement, but the thing is, all my motors are real darn slow. I definately do not see pins 3,5,7 flickering. They are always on. Pins 2,4,6 do turn on and off depending on the direction. The gecko green lights are on as well, which is expected.
I think I might know why everything is slow but I'm looking for a little confirmation here. I am temporarily using a variable DC power supply that supplies 20V and up to 20A. I checked while the motors were turning at max jog rate and I'm getting from 0.3A -0.36A on the PK motor, and about the same on the other two.
I have tuned the motors but still they are slow. Is the power supply my problem here?


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