Speedo/Tacho

[Mike Wattam <MikeWattam@domain.elided>]

Hi Alistair

It won't be the voltage stabiliser cuasing your problem, as this does not
control the tachometer.  All I can suggest is that you have either knocked
a cable end off, or aggravated a bad connection somewhere - probably an
'earth' connection on the instruments somewhere or in one of the cable
connectors.  If you have Lumenition (or similar electronic ignition)
fitted, maybe one of the wires is becoming detached - including also under
the bonnet.  Check connectors on top of the coil as these can also corrode
badly. 

Also check fusebox position 3/4 as the clips for the fuse itself are prone
to corrosion and thus volt drop.  This would also affect some of your
lights, and the wipers.

Mike Wattam
Chairman - Triumph Stag Register