Hello brains trust.
My vdo 02070109 tacho has stopped working. It's on a volvo penta md 2020c engine.
Armed with meter and circuit diagram I prepared to attack the problem only to be faced with a possible disconnected wire. These things are the sirens of boat electrics - push it back on and fire up and either fireworks or success.
The circuit diagram suggests that in some models there is a positive feed to power the tacho that goes to terminal 30 and it should be red.
The floating wire is red and runs from the ignition on switch so seems possible.
In the photo you can see the rear of the tacho with the 4 way connector on the left and the unoccupied terminal on the right. The disconnected red wire and connector is just below.
Sorry the photo is on its side. The red and blue wires are the top.
Sorry for the long explanation. The question is does anyone have this set up and is there a red positive feed to the single terminal on the right?
Thank you as ever.
Bristle
These people fixed a tacho which looks like yours. And they put their email address at the bottom for anyone who needs help.
verl900.wordpress.com/technical-articles/vp-md2020-tachometer-repair/
Ha. It's not the mysterious red wire - the D+ alternator connection has sheared.
Explains why there was also no charging, which I only just noticed.
Tacho working and charging restored with 1 wire - hooray!
Bristle
