MP6500 - measure Vref on pot or just at via?

(Context: I’m looking at trying the MP6500 instead of the A4988 to keep running longer as a 12V battery dies down in the field.)

The description of the MP6500 potentiometer-controlled version states “The VREF voltage is accessible on a via that is circled on the bottom silkscreen of the circuit board” – which is easy enough. I was wondering, though…

  1. It’s a via, right, so as long as I get the correct little hole, I should be able to measure it from the top side of the board, too… there just wasn’t room to circle it? It looks like it’s next to the unpopulated pads where the SMT resistors for the digital-control version aren’t.

  2. You do link to Claire’s excellent video with the trick of measuring VREF from the screwdriver that’s turning the potentiometer. Could you confirm that works on this carrier, too?

Thank you!


Yes, since that via is exposed on both the top and bottom of the board, you can measure VREF from either side. In case it helps, I circled the via in the image below:

Yes, measuring VREF through the screwdriver should work similarly on the MP6500 carrier.

By the way, if you are using something like a 12V lead acid battery, I suspect you would not actually get a longer run time by switching to the MP6500 since a discharged 12V lead acid battery should not drop below 12V (a fully charged 12V battery measures around 12.8 or 12.9V).


Thank you very much, especially for the “by the way” courtesy of which I now understand I don’t understand how batteries work :slight_smile: Googled my way to among other resources… and we’ll look at other options for extending runtime.

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