VM1000 RPM Input Setting - Adjustable?

[Toobuilder]

I've been flying for some time with the VM 1000 pulling RPM off the sensor that screws into the bottom of one of my Slick mags. Well, that Slick has now been replaced by an electronic ignition and the tach output of this new unit is apparently double the pulse because the VM now reads twice the actual RPM.

Is there a setting, jumper wire, or other trick to make the VM accept this new tach signal?

[Glas467]

Michael,

Depending on what software and hardware version you have, the fix can be as simple as a jumper setting or as difficult as a PC board hardware modification.

Assuming you have a fairly standard DPU P/N 4010066 or 4010067 with software ver 1.00x or 2.0 and a Rev H v1995 digital PC board, then all you need to do is remove the bottom cover from the DPU, orient the DPU lengthwise with the larger blue capacitors to your left and look for a set of 2 jumpers in the middle of the PC board separated by a small black chip. The bottom most jumper (as oriented) controls the pulse count, it is likely set to A for mag ignition, if so move it to position B and you should get the correct RPM reading.

If my description does not match what you are seeing, then you probably have an older version that will require a hardware modification.

All the best,
Reggie
http://vmsupport.weebly.com/

[Toobuilder]

Thanks Reggie. I happen to have easy access to the DPU at the moment so it should be an easy thing to determine.

Kind regards

[Glas467]

Michael,

Here is a picture (I was on the road when I posted last) to make it easier.

The lower jumper in the picture (JP2) controls the RPM pulse count, move it from position A as pictured to the next one to the right, position B for elec ign.

All the best,
Reggie
http://vmsupport.weebly.com/

[Toobuilder]

That worked perfectly.

You are awesome! Thanks very much.

[Glas467]

Glad to help!

Happy Flying,

[mikeg]

We solved the RPM issue going from Mags with Hall effect sensor to electronic ignition. We install the UMA Tach drive unit but had it built with ONLY two magnets instead of the standard 4 magnets. UMA will do this, no problem, now I get one pulse per crankshaft revolution, just like I did with the Hall effect sensor on the magneto.. It is 5v square wave output. Were now running dual Surefly and with the tack drive rpm sender, we get rpm readout even when we do a mag drop run up test.. we hope this helps...