Thread: G540 - 4 motor connection problem

1. Another thought

To troubleshoot the power supply, I have a Mastech 30 Volt 10 Amp variable DC switching power supply.

Should I plug this in ( although it's only 30 volts, and the other one is 48 volts ) and see if there is a difference?

Nick

2. I experimented again with the power supply and g540 , thismorning.

My other power supply, is only 30 Volt max 10 amps, but I can see the current draw on the system was down around 2-3 amps ( don't know how accurate that is ) I could not get the fault with the other system.

I then tried the keeling 48 volt 12.5 amp
with voltmeter on the output, it was steady but faulted at 48 volts, I adjusted the voltage pot to 49.9 volts, again stable, the multimeter coult not detect movement, but the fault happened faster at 50 volts, I dropped voltage to 46 volts, and faulted after 5 minute, then I tried 44 volts, and it took lots of simultaneous input, but it eventually gave a fault at 44 volts, I wound the pot all the way back, so it's now at 42.5 volts, and there was no fault so far.

sound like there is a feedback issue coming from somewhere?

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

3. Personally I would build a toroidal transformer type power supply

4. 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.
Last edited by paulus.v; 28-01-2017 at 08:17 PM. Reason: clarifications

5. Originally Posted by paulus.v
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.

6. Originally Posted by dachopper
I experimented again with the power supply and g540 , thismorning.

My other power supply, is only 30 Volt max 10 amps, but I can see the current draw on the system was down around 2-3 amps ( don't know how accurate that is ) I could not get the fault with the other system.

I then tried the keeling 48 volt 12.5 amp
with voltmeter on the output, it was steady but faulted at 48 volts, I adjusted the voltage pot to 49.9 volts, again stable, the multimeter coult not detect movement, but the fault happened faster at 50 volts, I dropped voltage to 46 volts, and faulted after 5 minute, then I tried 44 volts, and it took lots of simultaneous input, but it eventually gave a fault at 44 volts, I wound the pot all the way back, so it's now at 42.5 volts, and there was no fault so far.

sound like there is a feedback issue coming from somewhere?

Is there anything I can do to try make it work at 48 / 50 volts
Provided you're remaining below the maximum voltage of the gecko drives, and allowing a reasonable safety margin, it should make no difference.

I can't remember, but are there any LEDs on the G540 to let you know any statuses?

I'd suggest temporarily disabling the chargepump input on the G540, and see if fault still occurs. It could be a noise issue that with the higher power, the G540 isn't seeing a good charge pump signal, so it is disabling all the drives. However if that was the case, I would expect problems with the step/dir signals aswell, however that probably wouldn't be noticeable if you're not actually working the machine to notice a position loss.

7. Originally Posted by m_c
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.

8. 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.!!!!!!!

Originally Posted by dachopper
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.
Last edited by JAZZCNC; 29-01-2017 at 09:45 AM.

9. Originally Posted by JAZZCNC

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.

10. Originally Posted by Neale
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.
Last edited by JAZZCNC; 29-01-2017 at 10:28 AM.

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