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:

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.

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
resistor?

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?

A's:
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.

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

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

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

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

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

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

Greg

Greg,

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.

Mike,

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.

Greg,

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.

Mike,

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

Mike,

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,
Greg

Greg, you can use the Gecko forum as well:
http://finance.groups.yahoo.com/grou...drive/messages

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.

Thanks Gerald,

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


Greg

Gerald,

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

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.

Greg

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

Greg,
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. (miker@xmission.com)

-Mike

Gerald,

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.


Mike,

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,
Greg

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.

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.

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)?

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.

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.

Thanks,
Herb

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

Oriental Motors
 

Gerald,

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.

Thanks,
Herb

Herb,
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.

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!!!!!!!

JR,

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.

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

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?

J.R.,
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.

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 :))

Snap!

JR,
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.

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.

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 motor’s 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.

Thanks Gerald!