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<p>Have you disconnected the tach with the engine running and
confirmed it stops?</p>
<p>You can check the calibration using an old-fashioned trickle
charger but if it's not working with coil current passing through
it then it won't work on that either. The only thing you can do
(apart from sending it away to someone) is to open it up and look
for any broken connections in wiring and an the circuit board. If
you are familiar with electronics there are certain tests you can
do inside. This circuit
<a class="moz-txt-link-freetext" href="https://www.classictiger.com/techtips/motach.html">https://www.classictiger.com/techtips/motach.html</a> is of the early
tach with the external pickup and this one the later internal
<a class="moz-txt-link-freetext" href="http://www.mgb-stuff.org.uk/harvit.htm">http://www.mgb-stuff.org.uk/harvit.htm</a>. It can also be converted
to the later voltage pulse type with a module as here
<a class="moz-txt-link-freetext" href="http://www.mgb-stuff.org.uk/rvctach.htm">http://www.mgb-stuff.org.uk/rvctach.htm</a></p>
<p>PaulH.</p>
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<div class="moz-cite-prefix">On 08/08/2023 20:35, dave northrup
wrote:<br>
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cite="mid:3411356e650041da97b2be3a4baba303@ranteer.com">
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<p class="MsoNormal">I do not know the origins of the tach. I
have no idea what is inside it and I have not taken it apart.
The car came to me in kit form. I don’t really even know if
the tach worked. Any way to test it?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I do know that with the tach hooked up the
engine runs, so power is at least going through it. this is
the only source of power for the coil. Anyone have an mgb
electic tach to sell? I’d like to hook up something that is a
known quantity.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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