10 replies to this topic

[Razor]

Its a '76 Clubman S 3 clock gauge

Tacho stays on 10 or 1000rpm but doesnt move at all if engine revs
Turn the motor off and its goes down to zero or the lowest point.
all wires seems to be attached, connected on the back of the cluster White with black trace goes to the -ve side of the coil


I repaired the printed circuit as well as one part was torn







Can anyone confirm if the wiring is correct?

Cheers

[Razor]

Anyone PLEEEEAAAAAAAAAAAAAASE

[koss]

Anyone PLEEEEAAAAAAAAAAAAAASE

have you checked the wire from the -negative side of the coil upto the tako

[Razor]

Yes
Checked the connection with my multimeter and its good.

[Razor]

Anyone got a pic or can help me determine if my wiring is correct

[Gizzum]

I had the same problem when I bought a three clock setup from ebay, couldn't get it to work.... However after about an hour of googlin I came up with a diag



Took a while two figure this out but basically you chop the wire that goes between the dizzy and the coil and extend it onto the back of the tacho. Also makes a handy kill switch/immobiliser for the car as well if you stick a switch in there!

Also found this website that shows the old install distructions

LINK

Hope this helps

[Razor]

I'm never been good on electricals

Chop the wire that goes to the dizzy... is that the wire on the -ve side of the coil? the one that joins with the white/black wire for the tacho signal (bullet connector on tacho)
Where do I connect this wire then?

also what do you mean by chop? completely remove/disconnect the wire? or join a wire ?

[dklawson]

I'm afraid I can't offer help on the later gauges/dashes but I do want to add not of caution.

The schematic and link shown above are for Smiths RVI type instruments (current pulse sensing). That technology hasn't been used since about 1970. The cars with built-in tachs should have a single black/white wire going between the tach and coil (-) for the sensing circuit. Obviously there will be switched power and earth connections.

You may be able to install an RVI instrument on later cars but they certainly shouldn't have been stock. The RVI tachs don't always work with electronic ignitions and conversion/upgrade of them isn't cheap. Contact Speedy Cables for details and costs.

[Razor]

I live in australia
I understand the logic of connection and I believe that the 3 gauge cluster has some wierd earthing by using the blue printed circuit board.

the wierd thing is that the tacho needle goes right below 10/1000 rpm when started and stays there while running or revved as soon as you turn the engine off it goes back to zero
which is kinda working but not moving.
Checked if the needle is stuck or something blocking it but it can be move as it should manually by your finger.

Any more bright ideas?

[DYO776C]

I live in australia
I understand the logic of connection and I believe that the 3 gauge cluster has some wierd earthing by using the blue printed circuit board.

the wierd thing is that the tacho needle goes right below 10/1000 rpm when started and stays there while running or revved as soon as you turn the engine off it goes back to zero
which is kinda working but not moving.
Checked if the needle is stuck or something blocking it but it can be move as it should manually by your finger.

Any more bright ideas?

Hi there.
You know this could just be a faulty instrument, as in fact there are electronics inside, which in reality just drive a conventional moving coil instrument.

The electronics include a pulse shaping circuit, integrator circuit, (which provides a varying DC output depending on pulse repetition frequency) and a following DC amplifier.

If the DC amplifier or the integrator circuits go faulty, then the moving coil meter can be fed with a less than adequate voltage, and in fact this could be amplitude limited under certain fault conditions.

This would mean that some movement of the pointer could show between zero and say 1000RPM, with no further movement above that.

Trouble is unless you have electronic test gear available (more than just a multimeter) you will be hard pushed to check this. The best thing to do would be to try and beg or borrow another instrument to try.

[Razor]

borrowing is out as I just started with the minis and none of my friends have minis.
will have a look for 2nd hand unit or might install an aftermarket unit for the time being.

Cheers