Hi All,
I hope one or two of you may be able to help me, I have an
electric/electronic Smith's tacho from a Triumph 2500 P. I. saloon. When I
first acquired the car the tacho would work sporadically, when it stopped
working it could be awakened with a tap, later it would not wait at all so,
with my limited electronic ability I managed to find the fault. This turned
out to be a dry solder joint, in fixing this I managed to fry the component,
so I borrowed one from a four cylinder unit. The donated component had
identical markings and values, but in taking the unit apart to fix, I
managed to disturb both the adjustment points, those being, the platform
that adjusts the hair spring balances for the resistance to movement of the
needle, and the potentiometer or rheostat (not sure which title it goes by,
but there is only one adjustable electronic bit). Fee instrument works now
but is wildly out on without trying to blow the engine up will only read
about 2000 R. P. M.
Can anyone tell me which of these components to adjust first and what values
if any should they be set to. I have a reasonably accurate takeover
checking the engine speed, I do not have access to a wave generator or an
oscilloscope to simulate electrical inputs, is there any way to create an
input so I don't have to rev the engine? The tacho is of the through feed
type with the two bullet terminals (one male one female) and one Lucar
terminal for the live feed on the back plus an earth tag on the case. I
hope this is all the information you will need to be able to help. I have
tried to get replacement (not very hard though) but having got it working
again would love to finish the job on the basis, and I quote, "if someone
made it you can repair it" as this has always been my philosophy, though I
currently lack the specialist knowledge and equipment. Sorry I have been so
long winded!
!! Any thoughts on this will be welcomed!!
Thanks in advance.
Graham.
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