Stumped by new smiths 80mm tach install

[Robbiemo]

Hi everyone. I got a new smiths 80mm tach “RVC1006-00CB” that I’m trying to install on my 1960 Mini with a 1275 swap. I’ve hooked up the Red/Blue to the negative side of the ignition coil. The Red/White to the gauge lights. Black and Green to their respective colored whites behind the speedometer. And the White/Black and Brown/Slate are not currently used.

The lights work as expected and when given power the needle vibrates within the tach (regardless if the output wire is connected) but I can not get the tach needle to move off of zero.

Based on everything I’ve read and researched my wiring seems to be correct. I have the dip switches 1, 2, and 8 on on the back side of the tach. I’m not sure where else to go.

[Robbiemo]

An update. I somewhat foolishly was hooking power to the wrong side of the coil, forgetting that these cars started life as positive earth I ran my signal wire to the - instead of the +

However I’ve run into a new problem. The tachometer works perfectly for ~5 seconds when I start the car but then jumps straight down to 0 and won’t come back until I cycle the 12V power.

[Robbiemo]

Turns out it was the voltage regulator. I realize the tach shouldn’t be running through the regulator, but it did help me accidentally troubleshoot a problem I didn’t know I was having.

[AndyPen]

Thanks for all the insights, great to see you seem to solve things as you went along

[100BUR]

Hi I've just noticed your post.
I have had something similar for a few years which I have never managed to sort.
Tachometer is fine for about 12 miles or so and then bounces about and then drops to zero.
Switching the lights on brings it back to normal reading but then eventually it will do the same bounce about and drop to zero again.

I even bought a new Tachometer with exactly the same results,and tried adding an other earth.
My car is away at the moment having some work done I can't remember we're I took the 12v supply from,but will be investigating further when it's back.
Thanks for sharing
I had initially given up how to solve this
Cheers

[roger mcnab]

hi many years ago i fitted 1 of those tachos in my mini and just hooked to the battery with in line fuse worked well no problems
cheers roger

[100BUR]

I'm going to check we're is wired from when my cars back.
Some times the simple things are not always that obvious

[swifty]

I have taken back and tried 2 of these brand new rev counters to Minispares . No problem at all with a refund . I’ve wired them correctly and cannot get one of them to work . …. Shirley

[100BUR]

Swift
Yeah that's frustrating not getting them to work.
,I guess I could of sent it back,but it was about two years from original installing the tachometer before I could work on the car again.
Also I would like a functioning tachometer, and not an empty pod we're it's mounted

I've looked at the supply voltage and it is 12-17
I was wondering if a voltage regulating unit would smooth the supply out and keep it constant they are relatively inexpensive.

Maybe one of our electronic guru could shed more light

[swifty]

It’s strange that the wiring directions say use the red/ blue wire to neg on the coil but if that doesn’t work try the white wire ! ….gary at Minispares potters bar has the last one I returned and he is going to try it in his mini …. Shirley

[100BUR]

Yeah, I wondered about that..
You have to update us how he gets on
Cheers