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Re: Tacho's-Recalibrating Longish

To: "nikolai jaremka" <njaremka@yahoo.com>
Subject: Re: Tacho's-Recalibrating Longish
From: "Graham Stretch" <technical-iwnet@lineone.net>
Date: Tue, 15 Feb 2000 20:52:15 -0000
Hi Nikolai
Thanks for the suggestion, I have one of these and have done what you
suggest but because I adjusted both adjustable points in there it was only
correct at whatever point I set it and incorrect over the rest of the range.
I need to have some kind of brain surgery (does banging ones head on the
ground count) for not marking these things before fiddling and also I need
some kind of idea as to which thing to reset first and what method to use on
each. Any further help is much needed and will be gratefully received.

Thanks, Graham.


----- Original Message -----
From: nikolai jaremka <njaremka@yahoo.com>
To: Graham Stretch <technical-iwnet@lineone.net>; List Triumph
<triumphs@autox.team.net>; List Spitfires <spitfires@autox.team.net>
Sent: Tuesday, February 15, 2000 7:20 PM
Subject: Re: Tacho's-Recalibrating Longish


>
> a dwell tach will give you a good reading as it is used to get your
> points set right. (or your electronic dizzy set right)  let the
> engine idle with the dwell tach and then set your original tach to
> match.  you should be able to get one if you don't have one for about
> $10-12.
>
>
> --- Graham Stretch <technical-iwnet@lineone.net> wrote:
> >
> > 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.
> >
> >
> >
> >
> >
> >
>
> =====
> nikolai jaremka
> 72 spitfire mkIV
> east aurora, new york
>
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