The earlier tach with the magnetic pick-up (the wire goes through it twice
which makes just one loop, BTW) should only have one connector on the back
of the tach which is for the 12v supply off the cars green (or possibly
white on the earliest cars with the electronic tach) circuit. The only
other wiring is the red/white of the panel light and a ground. On an MGB,
at least.
PaulH.
MG Cars Webring MG Site of the Month - September '99
http://freespace.virgin.net/paul.hunt1/
(or if that URL doesn't work try )
(http://194.168.54.52/paul.hunt1)
-----Original Message-----
From: ldsp <ldsp@flash.net>
To: mgs@autox.team.net <mgs@autox.team.net>; Spridgets
<spridgets@autox.team.net>
Date: 16 September 1999 04:39
Subject: Tachometer conversion
>Alright lets see if I can explain this without messing up too bad. I am
>trying to convert an electronic positive ground tach to neg ground. Smiths
#
>RV12401/00 out of a 64 midget, works great on pos grnd presently. I went to
>PDLJMPR and followed the directions until the part about a green wire and
>reversing the resistor and a green wire. on my tach there is only one lug
>out the back of the tach and no green wire which ultimately goes to a diode
>on the circuit board closest to the tach face. The infamous Alan F. took
>apart one of his tach's for me and sure enough the green wire was present
on
>his so what gives. I am missing according to info 1 spade post on the back
>of the tach and a green wire which connects to it then to a post on the
>circuit board closest to the tach face. So that leads to my next question.
>Looking at the wiring diag for the midget there is 1 grn wire that hooks to
>the spade connector (which inside the tach is connected to the resistor)
the
>grn wire originates at the flasher unit which is fed from the fuse (term 4)
>so it would logically be the hot wire. Next is the white loop which has to
>be reversed ,The white wire starts at the ignition switch and goes to the
>tach, 2 loops then to the sw side of the coil (is it not like a current
>transducer and what you are actually doing is changing the current polarity
>?) And then are the 2 indicator lamps. So if I am missing a spade
connector
>on the back of the tach ( the one the green wire inside the tach is
supposed
>to be hooked to) what wire out of the wiring harness is supposed to connect
>to it as it does not show up on any of my wiring diagrams. Any help would
be
>appreciated.
>
>Leo
>
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