G540 - 4 motor connection problem

[Clive S]

Personally I would build a toroidal transformer type power supply

[paulus.v]

4x3.5A =14A and you have a 12.5A PSU. Am I missing something?

For a switching power supply you need to be at least 18A.

(edit: I may be wrong here but Leadshine, among others, recommend adding 1/3 more to the rated motor current when using a switching PSU; 4*3.5*4/3=18.66A).

For a linear one you will be fine with 10A.

(edit: a bipolar parallel steppper requires a maximum of 2/3 of the rated amps/phase; 4*3.5*2/3=9.33A).

I would go with a toroidal PSU as Clive said.

[m_c]

4x3.5A =14A and you have a 12.5A PSU. Am I missing something?

In short, yes.

And before I give a Jazz style response about people commenting on things they don't understand, go and read the gecko drive stepper motor basics guide, as they explain quite well all about power supply requirements for stepper drives.

[paulus.v]

In short, yes.

And before I give a Jazz style response about people commenting on things they don't understand, go and read the gecko drive stepper motor basics guide, as they explain quite well all about power supply requirements for stepper drives.

Sorry for that, I edited my post to better explain my point of view.

[JAZZCNC]

Jazz style response not sure I like sound of that. . .Lol

Anyway I think the answer is obvious but all of you have failed to RTFM.!!! . . . . . With 3.5A motor current set resistor isn't required.

However I'd still throw that switched mode supply away and build one.!. . . . As well not RTFM you didn't RTFF . . . Because you'd seen said many times NEVER BUY KIT.!! . .

EDIT: Just seen this.!!!!!!!

Is there anything I can do to try make it work at 48 / 50 volts

You don't want 50v or even 48V because the Geckos are only rated 50Vdc so doesn't leave big enoigh safety margin. You will KILL the drives quickly if run at this voltage.
44Vdc is about high as would run these drives from safety point of view. The 4-5v differnence will hardly be noticable in performance terms but the Smell of magic smoke will be.!!

If you want higher performance then sell the drives and use 80Vdc Digital drives with 70Vdc and then you'll see difference.! . . .Big one.!!

Gecko's are living on there reputation from years ago but sadly today they are behind in the Digital race.

[Neale]

Anyway I think the answer is obvious but all of you have failed to RTFM.!!! . . . . .

Not quite, Jazz - the problem is reading the Gecko manual. Their kit of current-set resistors includes the 3.48K resistor specifically for this drive. Why they use this daft value is anyone's guess, though. But then, Gecko are also responsible for the widely-quoted max voltage based on motor inductance formula which at best leads people astray - or perhaps it suits their drivers better? I also run Nema23 at 65V via a Chinese digital drive and I'm very happy with it. And a linear/toroidal PSU... And I have complete freedom to choose my own micro-step ratios and motor current at the flick of a DIP switch. Americans buy Gecko because they know that "American (products) are great". The rest of the world is forced to buy on price/performance/reliability alone. Oh, pity the rest of the world.

[JAZZCNC]

Not quite, Jazz - the problem is reading the Gecko manual. Their kit of current-set resistors includes the 3.48K resistor specifically for this drive.

Yes has do lots of other Manufactures who use this type of current limiting but just because resistor is provided doesn't mean you have to use the bloody thing does it.? . . . Only use if required and this motor doesn't require resistor.

Edit: By the way I don't think this is the problem anyway. Personally I'm guessing the PSU is faulty.

[m_c]

Not quite, Jazz - the problem is reading the Gecko manual. Their kit of current-set resistors includes the 3.48K resistor specifically for this drive. Why they use this daft value is anyone's guess, though. But then, Gecko are also responsible for the widely-quoted max voltage based on motor inductance formula which at best leads people astray - or perhaps it suits their drivers better? I also run Nema23 at 65V via a Chinese digital drive and I'm very happy with it. And a linear/toroidal PSU... And I have complete freedom to choose my own micro-step ratios and motor current at the flick of a DIP switch. Americans buy Gecko because they know that "American (products) are great". The rest of the world is forced to buy on price/performance/reliability alone. Oh, pity the rest of the world.

I'm sure they only supply that resistor to minimise people asking how they set 3.5A if they've not got a resistor.

The max voltage based on inductance is a valid figure. You can run higher voltage, however unless you're running the stepper motors at speed, it has no benefit and will do no harm.
Any problem will arise when the motor is spinning fast enough that back emf increases the required voltage to drive the set motor current through the motor windings, to the point where you get diminishing returns for the voltage applied.
The key thing to remember is just because you have a 65V supply, is the motor will rarely see that applied. While stationery the motor should only see the rated stepper motor coil voltage, as there is no back emf to require a higher voltage to get the rated current flowing through the motor windings. It's only as the motor starts turning and back emf increases, that the required voltage increases.
Combine that with the laws of physics, where by power = volts time current, and with a stepper using a couple amps running flat out at maximum voltage, will be getting over one hundred watts of power applied. How long do you think your Nema23 could handle that before overheating and demagnetising?

As I said, that Gecko guide is pretty good. I can remember Marris's posts over on CNC zone where he explained a lot about stepper motors, drives, and the theory behind the figures. He didn't build a very successful business by plucking figures out of no where. Which is essentially what you've done by saying your 65V supply hasn't given you any problems, despite you not understanding the theory behind why it probably really isn't a good idea.

[dachopper]

Jazz style response not sure I like sound of that. . .Lol

Anyway I think the answer is obvious but all of you have failed to RTFM.!!! . . . . . With 3.5A motor current set resistor isn't required.

However I'd still throw that switched mode supply away and build one.!. . . . As well not RTFM you didn't RTFF . . . Because you'd seen said many times NEVER BUY KIT.!! . .

EDIT: Just seen this.!!!!!!!



You don't want 50v or even 48V because the Geckos are only rated 50Vdc so doesn't leave big enoigh safety margin. You will KILL the drives quickly if run at this voltage.
44Vdc is about high as would run these drives from safety point of view. The 4-5v differnence will hardly be noticable in performance terms but the Smell of magic smoke will be.!!

If you want higher performance then sell the drives and use 80Vdc Digital drives with 70Vdc and then you'll see difference.! . . .Big one.!!

Gecko's are living on there reputation from years ago but sadly today they are behind in the Digital race.

I have read the manual, the drive IS DESIGNED to be operated at 50Volts, and already has a 10 volt buffer - it works up to 60 Volts.

I have measures the input voltage and current on the switch mode power and it is rock stable at 48/50/46/42 volts, whatever I set with the resistor

The total system current draw is only around 2.6 to 3.3 Amps - when I hooked it up to my 30 Volt power supply

[m_c]

Ignoring Voltage/Power supply discussions, what is the actual fault you are seeing?

Do the motors stop/stall, the drives fault out...?