Andy,
yes I am getting the voltage shift from what looks like -4.95 to +4.95. So that is correct it appears. My 4.80v estimation was when I had the setting at 10 as the manual states for MG calibration. But it does behave as you described
- Daniel
--- In PolySix@yahoogroups.com, Andrew Jury <andy@...> wrote:
>
> Hi Daniel,
>
> Well, I am about 6000 miles away in the Suffolk market town of Sudbury,
> United Kingdom! However, you are very close to Jed and I am sure he will
> make you a nice cup of coffee if you decide to drop in! ;-)
>
> Back to your MG issue. I am happy with all the waveforms you have reported
> back, but one thing concerns me. IC13 pin 7. You say it is at 4.8v. This
> means the MG is oscillating almost flat out! Between this pin and ground you
> should see the following.
>
> With the MG frequency set to 0 you should have about 4.95v. As you increase
> this pot clockwise you will find the voltage drops to 0v when you are at the
> 12 o¹clock position. As you increase around to 10 then the voltage will ramp
> up to about +4.95v. Can we verify that this is the case with your board? If
> it is stuck at +4.8v then we can have a look at both the multiplexor and
> buffering stage for faults.
>
> On a working board MG frequency set to 10 give about 50-60Hz at CN6-1. I
> just measured it!
>
> Cheers,
> Andy
>