P-MAG Tach output to AF3500

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Wicked Stick
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P-MAG Tach output to AF3500

Post by Wicked Stick »

Just thought I'd post this in the hopes it may help others who have the same setup as I do.

I had initially gone "by the book" to setup my tach signal from pin 6 on the P-mag and had moved that signal wire from the AFS harness from pin 32 to pin 33 as their manual describes. I also had both set to 2 pulses per revolution. With all the wiring and settings done by the book, I could NOT get an RPM reading in this configuration.

I tested the output voltage on the tach terminal of the P-mag once in setup mode and at TDC, and it was showing 11 volts instead of 12, but I am thinking that the pulse frequency is what might be the cause of it not working at that voltage. So, after talking to Trevor at Advanced, we decided to add in the Diode to the P-mag and drop the tach signal voltage down to 5 volts and move the wire back to pin 32.

Once I did that, the RPM came alive, albeit now the tach was indicating twice the speed it should have, so then I had to change the AFS to 4 pulses per revolution and that fixed it down to the properly indicated RPM as the engine ran, verifying it with my portable optical digital tach.

Hope this helps others down the road.
Dave "WS" Rogers
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Spike
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Post by Spike »

Great info, Thanx!! I imagine that will come into play for me sometime in the future.


Spike
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