PWM Settings

[john swift]

I saved this G540 VFD circuit from CNCZONE



if you add a 10uF capacitor I 'd connect the output terminal to 2 diodes to prevent the output being taken below the ground or above +10V supply terminals




John

[Neale]

If that's what's inside the G540, then clearly there is an appropriate low-pass filter that should take out the worst of the ripple and leave a reasonably clean analogue output. In that case, the 10uF capacitor is not needed. And the OP's problem lies elsewhere...

[john swift]

I expect the G540 PWM circuit was designed replace the 5K potentiometer speed control for the original speed control boards as used in the machines like my old machine mart CL300M lathe

see this post
http://www.model-engineer.co.uk/foru...s.asp?th=38809

John

PS

the G540's PWM circuit was posted in a reply by Geckodrive
(Marcus Freimanis I think )

[Ger21]

As I told you on the Mach3 forum, you have Mach3 and the G540 working correctly.
The problem is that your VFD is giving you the wrong frequency.
2.42Volts on the analog input should be roughly 100Hz (96.8).

[Gunar]

....The problem is that your VFD is giving you the wrong frequency.
2.42Volts on the analog input should be roughly 100Hz (96.8).

Just to clarify the 2.42v is from the G540 terminals T7/T8 (ACM or ground & Vout). The VFD sends to G540 throught terminal +10V and ACM 9.88v

[Ger21]

Right, but the 2.42V goes back to the VFD, correct? The VFD uses that to set the frequency, and should be setting it at 96Hz.

[Gunar]

Correct. BTW Gerry I was told on Mach3 there is the "Calibrate Spindle" on the Functions Config menu. Is this any good for me to calibrate my spindle?

[Gunar]

if you add a 10uF capacitor I 'd connect the output terminal to 2 diodes to prevent the output being taken below the ground or above +10V supply terminals John

John there are 3 diodes on your schematic. Should I use 3?

[Gunar]

if you add a 10uF capacitor I 'd connect the output terminal to 2 diodes to prevent the output being taken below the ground or above +10V supply terminals John

Sorry for the mistake on my previous post John. I have these capacitors
0.47uF 400v, 100uF 25v, 0.047uF 100v. Would any of these be suitable?

[Gunar]

I also found these
10mF 50VMP, IEC NP 4.7MFD 50V, IEC NP 16MFD 50V