Tacho not working

[Almac]

Guys, I fitted a Zeeltronic PDCI-24V to the bike a few months ago, I've now just got round to programming it and firing it up for the first time.

The bike seems to run fine but my tacho doesn't work anymore. From the Zeel wiring diagram I've connected the grey wire from the tacho direct to the Y/G (yellow/green) wire on the Zeel (Rev Counter).

The tacho had been working ok before, I see there's another input, non original rev counter G/B, on the Zeel. Should I have wired to this, wouldn't have thought so but just asking before I start stripping it all down again .

Cheers, Alan

[rz500guytexas]

Try an orange wire from a ignition coil.

[Almac]

Thought I’d follow this one up as the response was deafening and it may be of help to others.

Basically, got the tacho to work today with the help from Borut. He suggested connecting a 47V zener diode in series with the Zeel tacho output and the grey wire to the instrument.

This would drop the input volts so I guess previously the volts were too high and saturating the instrument.

[rz500guytexas]

What the heck does the Zener diode do? Has something to do with electron flow in one direction I know but why that particular one. I had issues with tach after installing Zeels on both the 250 and 500. Be nice to know the explanation.

[Almac]

I’m not an electronics expert but I guess Borut is.

Zener diodes can be used to provide many different power supply options. They can be used as a voltage regulator but I’m guessing in this instance it’s getting used to shape the output waveform from the zeel, probably using the zeners ‘clipping’ properties.

As I mentioned before, maybe the standard output signal is too high for the tacho, I did measure something like 150v from the Zeel output but this was with a crap multimeter, I should have used my scope to get a more accurate level and waveshape.

All I can say is the tacho now works , although a proper Zeel manual would be helpful.

[MK]

In a nutshell: Imagine it acting as a voltage limiter clipping down a 150 or 200 V rectangular signal to just 47V.

https://en.m.wikipedia.org/wiki/Zener_diode