Problem- G540 and KBMM-125

[maddios]

Hi guys, Finally got all of my electronics sorted out and wired up my electrical cabinet, now just trying to tune everything nice and noticed something weird.

I'm using the 0-10v output from the G540 from SmoothStepper PWM and feeding it into a KBMM-125 DC motor controller, the motor controller has speed pot input, with the high side at 12v, I turned down the max speed pot so that it maxes at 10v like G540 asks for and then fed the 3 wires into the G540. I'm able to control my spindle rpm now and thought all was good...

However today I noticed that the output from the G540 is not linear for some reason, I put in an rpm of 1000 and when I measure the output voltage from the G540 on pin 8 it's at 1.66v, but at 2k it's at 2.8 and at 600 it's showing 1.1, totally not linear. Is there some sort of adjustment I need to do to the G540? or is this mach acting up?

I guess next step I'm going to put a scope on my smoothstepper output to make sure that it's generating a proper PWM signal width.


Currently I have my SS configured for PWM with a frequency of 2000, in spindle setup for mach3 I have base freq set to 50. In spindle control I have tried all different speeds and there seems to be no effect at all. And in pulley settings I have my min at 0 and max at 12000 with a ratio of .4 (My motor has a max rpm of 30k and is geared 1:4).

I hope what I wrote isn't confusing.

[maddios]

Hm, I think my G540 might have been broken, hence the weird curve. Today I tried to do some more tests and now it's not outputting anything on pin 8.

I put it on a bench now, feeding it 30v and pins 7-9 are getting input from a 9v battery (tested it's putting out 9v), and no matter what pwm I send it I get no voltage output (I see it go from like 0.01 to 0.05 when it should be at like 4.5v) when I try any range, say 50%.

Is there something I can look at inside? Bought this thing a while ago, new, from a guy on ebay and it's been way over a year.

I'm sort of at a loss here as it sort of degraded on its own, maybe a loose contact or a bad solder, I'm not sure what revision mine is, the little white sticker wiped off.

[oraclepoet]

I would like to connect a G540 directly to a KBMM-125 motor controller. I don't seem to quite grasp how the 3 terminals for a remote pot on the KBMM-125 can be connected to the Gecko G540. Can anyone help?
Thanks
RonE

[maddios]

Well, the G540 simulates a pot with the way the pins are setup on the board. It needs a high, a low and then the middle pin simulates the sweeper arm. You basically wire the G540 in as a regular pot as it is on the wiring diagrams

However the KBMM-125 outputs 12+V so when I was wiring up my G540 I was afraid to hook 12v straight to the G540 since the 540 has 10v in its spec (might be fine though, your call) So what I did instead was to put a 7809 voltage regulator on the 12v line coming from the Kbmm to the G540 to bring it down to 9v, this obviously limits my top speed by about 20% but in my case it was fine.

Let me know if you need actual wiring help and I can try to come up with a better explanation for you.

[oraclepoet]

Thank you for the quick response. It's very nice to be able to ask someone who's done it. Can you tell me the G540 pins for the KBMM high, wiper, and low?
Regards,
RonE

[oraclepoet]

I did try hooking the KBMM remote pot high to the pos 9 on the g540. I connected the wiper pin to pos 8 and the lo pin to Pos 7. I don't think that's correct because the motor ran half speed and I could not control it. Any advice?

[Mariss Freimanis]

The G540 uses an LMC6032 op-amp as an active 3-pole low-pass filter. The absolute maximum voltage rating for the op-amp is 16VDC. The minimum op-amp output load resistance is 5K and there is a 470 Ohm resistor in series with the op-amp output to protect it against improper load connections.

If you think your G540 isn't working properly or you suspect it is damaged, feel free to return it to us for evaluation. If it is repairable, we'll repair it for free and that includes free return shipping. It doesn't matter who you bought it from or how long ago; they are still our drives and we take care of them.

Mariss

[maddios]

When my g540 failed for some reason it didn't do anything at all, so if yours is running at 1/2 of your input voltage I'd check your mach3 settings, or whatever you use to generate the pwm.

The settings are VERY convoluted so it took me awhile to get it all tuned up right. specifically things like the carrier frequencies and pulley settings.