Whats inside a SMITHS revcounter ?

[JC T ONE]

Hi all,

who knows anything about a SMITHS revcounter ?

the one in my car (RVI type) gets the pulses from the White wire (12volt plus, to coil)

the car runs perfect, if I connect an extra wire, direct from the fusebox, and put it on the coil, but as soon as I remove it, the car runs bad again
I changed the bottom part (electrical section) of the ignitionlock, and cleaned/checked the connectors & wires, all the way to the coil, and all is OK.
So this leaves the tacho

Jens Christian

PS the problem started over night, the day before she ran perfect,
next day she wouldnt start, and when she finally did, she ran like a pig

edited 21/8 = new info

[36inter]

I'm sorry JC I have no constructive reply, electrics (amongst many other things) are not my strongpoint, I always it put down to Gremlins

[pad4]

had a look in mine and found some wires and nuts and bolts and a bulb..

[JC T ONE]

I always it put down to Gremlins

Hmm, do you a trap to catch these "bad boyz"

[JC T ONE]

had a look in mine and found some wires and nuts and bolts and a bulb..

Mine has more stuff then, I have a needle, and a spring too

[Smiffy]

The white wire should go from the A4 fuse, into the tacho and out to the coil.

[JC T ONE]

The white wire should go from the A4 fuse, into the tacho and out to the coil.

Thanks, and it does, I followed it, all the way from the ignition lock, to coil.


I have now googled it, and found out that SMITHS did 2 different tacho,s -

one is a RVC for picking up the pulses with the points.

The other (my type) is a RVI, so its not "rebuilt" as I first thought

this type pick up the pulses, from the 12 volt to coil wire (all White) .

Since there are a sticker from a gauge shop on it, I asume it has failed before


Jens Christian

[Smiffy]

I have now googled it, and found out that SMITHS did 2 different tacho,s -

one is a RVC for picking up the pulses with the points.

The other (my type) is a RVI, so its not "rebuilt" as I first thought

this type pick up the pulses, from the 12 volt to coil wire (all White) .

Since there are a sticker from a gauge shop on it, I asume it has failed before


Jens Christian

RVI (current sensing) these will only work with points, well unless you rewire it and turn it into the later RVC (voltage sensing) type. RVC will work with either points or electronic.
Basically the RVI type has a small coil, this uses the current flowing through it from the ignition coil to generate the power to move the needle.

[JC T ONE]

RVI (current sensing) these will only work with points, well unless you rewire it and turn it into the later RVC (voltage sensing) type. RVC will work with either points or electronic.
Basically the RVI type has a small coil, this uses the current flowing through it from the ignition coil to generate the power to move the needle.

Hi Smiffy,

well I only know what I found on the web

http://www.super7.dk/instruments.html

I dont know whatever mine was repaird ? or rebuilt ?

but it say RVI 2430/00 on the dial.

So maybe it wasnt changed?.

Jens Christian

[Smiffy]

RVI (current sensing) these will only work with points, well unless you rewire it and turn it into the later RVC (voltage sensing) type. RVC will work with either points or electronic.
Basically the RVI type has a small coil, this uses the current flowing through it from the ignition coil to generate the power to move the needle.

Hi Smiffy,

well I only know what I found on the web

http://www.super7.dk/instruments.html

I dont know whatever mine was repaird ? or rebuilt ?

but it say RVI 2430/00 on the dial.

So maybe it wasnt changed?.

Jens Christian

Yeah jens wasn't disagreeing with what you said only trying to add to it. On the back where the white wire loops through the plastic block, is effectively a transformer. As the current pulses through, it triggers a current from the transformer. This current then drives the tacho, which is really a ammeter. As all it does is measure the current generated by the transformer.
You'd need to open it up and have a look if it's been converted, it'll have a extra board (PCB) in it. And the white wire wont be looped inside the case, it'll just go in and out.

[kariya]

I'm 100% agree to comment of smiffy.
The photo is my Lucas RVI base unit and current sensing coil, it removed from 1966 Lotus Elan.
L.Green/Red line is wrong. I changed the number of the turns, but did not work well.
Hope it helps.

kariya

[kariya]

mistake
Smiths ← Lucas
kariya

[JC T ONE]

Yeah jens wasn't disagreeing with what you said only trying to add to it. On the back where the white wire loops through the plastic block, is effectively a transformer. As the current pulses through, it triggers a current from the transformer. This current then drives the tacho, which is really a ammeter. As all it does is measure the current generated by the transformer.
You'd need to open it up and have a look if it's been converted, it'll have a extra board (PCB) in it. And the white wire wont be looped inside the case, it'll just go in and out.

Hi Smiffy,

I havent had my dash out, since I put in my 8 track, and this is more than 3 years ago,
but I remember how the back of the tacho looked.

It has one wire (think it was Red?) that sits on a spade plug.
Next to it, is the White wire from ignition lock, sits with a round Lucas plug, and comes out again, also in a round Lucas plug.
One is male, the other female, all 3 is fitted to this Brown type of electric board material.
The hole for this looked "factory" made.
All this puzzled me, as I had only seen the type you mention, with the White plastic block / looped wire.
I remember when I rebuilt the wiring loom, that I thought it was strange, that only ONE wire came from behind dash, to coil.
I am use to 2, on a SMITHS tacho (only seen this type) .
Then I found the little sticker, from a gauge shop, so I asumed it was rebuilt?

I will see if I get time, to go to the garage this week, and take the dash out.

Then I will disconnect the White wires, from the tacho, and see if she behaves?

Jens Christian

[JC T ONE]

I'm 100% agree to comment of smiffy.
The photo is my Lucas RVI base unit and current sensing coil, it removed from 1966 Lotus Elan.
L.Green/Red line is wrong. I changed the number of the turns, but did not work well.
Hope it helps.

kariya

Hi Kariya,

This is the type I normally associate with SMITHS .

There is the White plastic block, with the looped wire.

So these parts were removed from your tacho ?

Jens Christian

[Smiffy]

t has one wire (think it was Red?) that sits on a spade plug.
Next to it, is the White wire from ignition lock, sits with a round Lucas plug, and comes out again, also in a round Lucas plug.
One is male, the other female, all 3 is fitted to this Brown type of electric board material.
The hole for this looked "factory" made.
All this puzzled me, as I had only seen the type you mention, with the White plastic block / looped wire.
I remember when I rebuilt the wiring loom, that I thought it was strange, that only ONE wire came from behind dash, to coil.
I am use to 2, on a SMITHS tacho (only seen this type) .
Then I found the little sticker, from a gauge shop, so I asumed it was rebuilt?

I will see if I get time, to go to the garage this week, and take the dash out.

Then I will disconnect the White wires, from the tacho, and see if she behaves?

Jens Christian

I think it was the earlier tacho's that had the loop outside the body, on later ones it was all moved inside.
Another possibility is it's one of the aftermarket tacho's smiths made, rather than a factory fitted item. I have one with 7 wires on the back. Which can be used on four, six and 8 cylinder engines, just by swapping the wire configurations around.

[JC T ONE]

I think it was the earlier tacho's that had the loop outside the body, on later ones it was all moved inside.
Another possibility is it's one of the aftermarket tacho's smiths made, rather than a factory fitted item. I have one with 7 wires on the back. Which can be used on four, six and 8 cylinder engines, just by swapping the wire configurations around.

This could be, the car is a 1973, and the ones with the loop, on the outside, seem older.

I cant say if mine is a aftermarket, but I guess Wood & Pickett bought them direct from SMITHS.

I have a few of those SMITHS, accessorie tachos, and they all have 7 wires.
But they are smaller, and in plastic housing, you could also get a clock.
Volvo had these, both as an accessorie, and standard in the 123GT.
http://www.automania.be/files/Image/art ... 7P1076.jpg

[Smiffy]

Yep thats the one, 3 for cylinder number (brown, blue & black) and 4 wires to the cars wiring. White - Coil, black - earth/ground, Green - earth/ground and Red to A4 fuse.

[JC T ONE]

Yep thats the one, 3 for cylinder number (brown, blue & black) and 4 wires to the cars wiring. White - Coil, black - earth/ground, Green - earth/ground and Red to A4 fuse.

These are very nice I have one in my 1966 Volvo 122 Sport/Ragtop.
On the opposit side of dash have I fitted the clock, from the same series.
Both dials are genuine Volvo .

The one in Woodis, looks like this, but have RVI on the dial surface.

[Smiffy]

Yeah got one similar to that, chrome bezels slightly different iirc. Actually took mine out of a MGB, back when you could still find 'em in scrapyards.

[JC T ONE]

Actually took mine out of a MGB, back when you could still find 'em in scrapyards.

Ahh I remember, back when it was interesting to pay a visit to the scrapyard

These days you just see modern sheit, and Japanes plastic