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reza forushani Tue 27 February 2007 02:55

How do you know when a Gecko has a fault. I was running the system and something happened the Gecko is displaying a green and red LED. Mach continues to run as if everything is Ok but the motor is not running and Gecko has faulted.
1. How do you get to know if that's happened. Geck is inside the control box and you don't see when it has faults
2. Does Mach not know about this to stop the program. If this Gecko is on one X-axis, that motor stops but everything else is running.

Gerald_D Tue 27 February 2007 03:17

You make an extremely important point. The whole MACH/Gecko approach is very much open-loop with one axis not knowing about a problem on another axis. The guys have been talking of closing the loop, but nothing is available yet.

This a very good reason to use the highest quality workmanship and materials when building your own system. And to make sure the Gecko (and other components) are installed in accordance with the manufacturers information. You don't get second chances.

Gerald_D Thu 01 March 2007 07:55

The closed loop / encoder discussion continued here

Jon Conner Fri 02 March 2007 08:01

Hi I am about to update my G202's with some new steppers that are 4.2 amps. I was going to change the resistor to 75k, and "tune" the motors with the pot on the back of the drive. Any suggestions or am I missing anything? Thanks

christipher saint denis Sat 31 March 2007 12:27

I have the hardest time formulating my questions. There are so many aspects to wiring this project and the fact that I am very new to this sort of thing does not help. I have collected the motors and most of the electrical components.

I am having trouble understanding how to correctly wire my AnTeck PS-8N70Rxx power supply to my Gecko G203 driver.

Info from the Gecko G203 manual says:


(TERM. 1) POWER GROUND Connect the power supply ground to term.1

(TERM. 2) +15 TO 80 VDC Connect the power supply ?+? to this terminal

My 110v line has black(hot), white(neutral), and Green(ground).

My Antect power supply has 2 red wires and 2 black wires. AnTect states that in connecting my 110v line both the Anteck reds are connected to neutral(white) and both Anteck blacks are connected to hot(black). That I understand well enough(hopefully)? What I don't understand is where is this "POWER GROUND" wire to be connect to the Gecko g203 term.1. Are they asking for the ground(green) wire for my 110v supply line. This "Power Ground" is throwing me off.

The Anteck 70Vdc 11A unregulated output block has three terminals and from the Antect info sheet the out side two are + and - and the inside term is unlabeled.

Thanks for you time. Really, I appreciate it!

Gerald_D Sat 31 March 2007 12:52

Christipher, the power ground for the Gecko is the terminal marked "-" (reference) The middle terminal should be "dead". They use a 3-position terminal to get some space between the + and - connections because these can make very good sparks when they touch.

They are NOT asking you to connect the Gecko's terminal directly to ground wire of the 110V incoming.

Can you post some photos of your power supply?

christipher saint denis Sat 31 March 2007 14:27

Thanks so much for the information. I would be glad to post some photos of my supply.

Christipher did post photos and I moved them to the power supply section here

von hous Thu 09 August 2007 09:16

1 Attachment(s)
Hi Gerald_D and to the others into this group.:)
I am going to use steppers motors and I want to ask you what i must do to connect those steppers motors (look attachment) to geckodrive G320v.
I am not wise in the electonics and i want to understand the maths to do it.
Also in 4'axis controller system what size of power suplies i must use. Please keep it simple, with some "exaples" to understand.
thank you.:)

Attachment 260

Richards Thu 09 August 2007 10:01

The Gecko G320 is for SERVO motors. You will need to use the G201, G202 or G203 modules with STEPPER motors.

(I have a G320 with a servo motor on my test bench and it works very well, but without a lot of gear reduction, the servo motor would not work on a rack and pinion driven CNC router.)

Gerald D Thu 09 August 2007 11:50

Welcome von hous!

The Slo-Syn motor 103-807 is a stepper motor, but it is not good for the MechMate if you want to put the pinion gear direct on the motor shaft. The shaft is too thin.

Also, the GeckoDrives work much better (60%?) with motors that have a square body shape. That Slo-Syn is round. The square body motor contains more iron.

As Mike said, you need either the G201, G202 or G203V drives from Gecko for stepper motors.

Let us first find out your final motor choice before we talk about the drive.

von hous Thu 09 August 2007 15:46

Hi Gerald D,
It was my fault, I mean 203V, but in a rush I write the wrong geckodriver.
I am going to build a small version of your machine.
Dimesion is about 1m X 0,6m. I think that is ok also those steppers motors. What do you think. Any advise?:confused:

Also by yours opinion which stepper motors is going to work best with the gecko. I mean which is the best for my machine.
(In the future I maybe use the same controller+steppers motors with a much larger machine), but for now -for the space that I have in my home- that is the best I can do. :mad:

Gerald D Fri 10 August 2007 00:29

Von hous, if you make the MechMate smaller, you still have to keep to the same motor size. The recommended motors are fully discussed in this thread: Selecting motors for the MechMate Read the first post very carefully.

Gerald D Fri 10 August 2007 13:23

Current limit voltage instead of resistor
A discussion on the geckodrive yahoo group in the last day:

Q: Does anyone know if it is possible to set the current limit of a G203 (and other Gecko Stepper drive) with a voltage in place of the current set

A: Yes, it's easy. The voltage on the G203V terminal 11 is proportional
to motor current. The relationship is 2.12 Amps per volt, 3.3V
maximum. The source impedance should be less than 500 Ohms to
swamp-out the effect of the internal 47.5K pull-up resistor to 3.3V.

Q's: Three questions if I may:

1) Terminal 12 is commoned to terminals 1, 10, both, none(floating)?

2) If terminal 11 of multiple drives are supplied by one voltage
controller, are there risks of a single drive fault impacting on others?

3) Does a voltage control apply to G201 and G202?

1) Terminal 12 is common with terminal 1. The difference is terminal
12 is a "quiet" ground. The top inner layer of the printed circuit
board is a ground plane. It is divided into two sections, power ground
and logic ground. Power ground carries the large motor currents, logic
ground carries only small currents. The two connect at a single point
only (at the ground end of the current sense resistors).

Terminal 10 goes to the cathodes of the DISABLE, STEP and DIRECTION
optoisolator LEDS only. It is electrically isolated from the rest of
the drive circuit.

2) Terminal 11 has a 47.5K resistor pull-up to 3.3V and a 100K / 100nF
low-pass filter going to an op-amp input. The op-amp input is diode
clamped to GND and 3.3V with a pair of Schottky diodes. A worst-case
failure in the drive results in terminal 11 still having at least a
33K input impedance.

3) All of our other step motor drives have a 0.39 Amps per Volt scale.
An 18V input gives a 7 Amp current output while a 2.5V input (minimum)
gives a 1A output current. The 0V to 2.5V input range is not recommended.

The G203V input range is 0V to 3.3V which results in a 0A to 7A
current output range. The scale is 2.12 Amps per Volt.

Marc Shlaes Fri 10 August 2007 14:05

I'll go ahead and say what probably many others are thinking.

"I wish I had a clue what this said!"

Gerald D Fri 10 August 2007 14:16

Marc, this is stuff you might want to know when you build the third MechMate. Don't worry about it! :)

Marc Shlaes Fri 10 August 2007 15:01

Thanks, I needed that! Now I can go from this :eek: to this :D.

Greg J Sat 11 August 2007 15:06

I found some 12K resistors :D (actually the 12K read low at 11.75 so I added an .82K in series).

Anyways, when power is applied to the drivers, 3 operate normal, but one does not. It has the momentary red led and then nothing. There is 70VDC to terminals 1 and 2. If I had a blown fuse, would the red led show at all?

Any suggestions?


Greg J Sat 11 August 2007 15:07

Ooops, I'm using the 203V Gecko drivers.


Richards Sat 11 August 2007 18:47


Here's some info from the G203 manual:

ERROR LED: The RED ERROR indicator is lit when:
1) During power-on reset for 1 second when power is first applied to the G203V.
2) While the DISABLE input is active.
3) When there is a short-circuit on any motor output. Momentarily activate the DISABLE input to reset.
4) During over-temperature shutdown. The LED automatically resets when the drive temperature drops.

I'm guessing that somehow one of the motor's leads is shorted.

Greg J Sat 11 August 2007 20:33


I did a continuity check between phase A and phase B coils and everything looked OK (I'm configured Uniphase), no short between coils.

Just a reminder, that when I first (the very first time) powered up, I did not have the 12K resistors on the current set "ports" of the Gecko drives. During that first time, this same drive showed yellow LED while I was cooking the motors. The other 3 drives, showed green LED's.

I wonder if its advantageous to change drives. Switch number 3 with number 4. I'll wait to see what you think.

Richards Sat 11 August 2007 20:58


The yellow L.E.D., which is available on the newest G203 drives has a special function. According to the manual:

FULL POWER LED: The YELLOW FULL POWER indicator is lit when the motor is turning fast enough to generate
maximum possible mechanical power. Power is torque times RPM and power output reaches its maximum value
when this indicator is lit. Use this indicator to verify your motor is optimally geared to the load.

I would try switching two of the stepper motors to see if the problem follows the motor or if it remains with the stepper driver. In case the stepper driver has been damaged, Mariss has a special 'opps' policy where he will replace a stepper driver as long as you explain exactly what happened. (He uses the 'opps' data to design even better drives.)

I can't imagine that running the motors for a very short time without current limiting resistors would have 'cooked' either the stepper driver or the stepper motor, especially if the table covering was not hurt. I've run a PK299A2B-SG3.6 drive with 70V, when 25X the drives rated voltage was 35V. That drive got really hot. In fact, I smelled it before I burned a fingertip when I touched it. Other than getting really hot, both the stepper and the stepper driver still work perfectly fine.

Greg J Sat 11 August 2007 21:24


I switched out motors (changed motors with drivers) and no change. From this test, its not the motors. I'd rather have a driver go, than a motor.

I think I'll switch driver also. You never know if I have a bad BOB.

Give me a little time and I'll report results.


Greg J Sat 11 August 2007 21:40


Nope, I switch the DIR, STEP, and COMMON, leads on the BOB and no change.

I'll see what the boys at Gecko have to say.

Thanks for your help on a Saturday night.

We're a strange lot who enjoy our play on a fine evening.

"Piloting on the Mississippi River was not work to me; it was play--delightful play, vigorous play, adventurous play--and I loved it . . ."
- Mark Twain in Eruption

Have an enjoyable time,

Gerald D Sat 11 August 2007 23:21

Greg, you can use the Gecko forum as well:

Gerald D Sun 12 August 2007 02:41

I would not rush to call the one drive suspect until I had done a lot of swapping and checking. Leave the suspicious drive to one side for now and focus on getting some motors to turn on command. Once you have control (understanding) of the whole process from keyboard to motor motion you are then better equipped to diagnose faults.

Greg J Sun 12 August 2007 09:58

Thanks Gerald,

Will do. I'll try to get some motors turning today.


Greg J Thu 23 August 2007 22:10


That yahoo/gecko drive forum is addicting. The way Mariauss (Not spelled correctly) solves problems is worth reading.

Originally Posted by Gerald D View Post
Greg, you can use the Gecko forum as well:

Greg J Mon 27 August 2007 21:44

Gerald / Mike / anyone,

Received G203V back today. "No problem found. Drive working properly" was Gecko's notes.

It has to be in the Mach 3 config. somewhere. I did notice on the PDMX-122 BOB, that pin 4 of J2 is not lit. Pins 2 & 3 of J1 are lit, Pin 5 of J2 is lit, Pins 6 & 7 of J3 are lit and Pins 8 & 9 of J4 are lit.

The suspect G203V is connected to J3.

Any help is appreciated. Just for the record, I've never operated a CNC machine, wrote any G code, let alone, built a CNC router. This is all from the ground up for me.


Gerald D Tue 28 August 2007 01:20

If you swopped drives without doing anything else, and the fault swopped as well, then it is a faulty drive.

Richards Tue 28 August 2007 07:26

Here's the way that I have Mach 3 configured for my G203 stepper drivers:

X-axis enabled (GREEN Check Mark), Step = pin 3, Direction = pin 2, Step Active Low = RED X, Dir Active Low = RED X

Y-axis enabled (GREEN Check Mark), Step = pin 5, Direction = pin 4, Step Active Low = RED X, Dir Active Low = RED X

Z-axis enabled (GREEN Check Mark), Step = pin 7, Direction = pin 6, Step Active Low = RED X, Dir Active Low = RED X
A-axis enabled (GREEN Check Mark), Step = pin 9, Direction = pin 8, Step Active Low = RED X, Dir Active Low = RED X

Slave Axis: A is slaved to X

On the PMDX-122:

JP1 is set with the jumper on the bottom (between GND and the center pin)
JP2, JP4, JP5 are all jumpered with the jumper on the top two pins (closest to the cable connector)
JP3 is jumpered with the jumper on the top two pins (away from the green connector)

A 12V power supply is plugged into J11

NOTE: The L.E.D.s for pins 2, 4, 6, 8 will be ON when the steppers are turning one directions and OFF when the steppers are turning the other direction. 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.

With a multi-meter, check your wiring between the problem G203's Step, Direction, and Common pins and the PMDX-122's Step, Direction, and Common pins to verify that resistance readings between connection pins shows zero resistance (with the power off!).

If that doesn't work, email me your telephone number and the best time to call and I'll try to help you troubleshoot the circuit. (


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