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Tach Bounces while Shifting

September 10, 201113 yr

This is pretty much an educated guess: I think the 100uF cap in the circuit could be kaput and the diode/cap "tank circuit" is not working. Transients (back emf) on the tach's anemeter are not dampened correctly when going from higher rpm to lower rpm during a gear change.

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September 10, 201113 yr

comment_366000

OR it could be a broken spring in the needle assembly

Read this great write up: http://www.classictiger.com/techtips/motach.html

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6 years later...

January 5, 20187 yr

comment_539025

73 240z Tach Circuit Schematic

240z tach schematic.jpg

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6 months later...

July 28, 20186 yr

comment_554015

On 1/4/2018 at 8:58 PM, 240260280 said:

73 240z Tach Circuit Schematic

I recenly replaced my 4 year old battery with a brand new of 600 amperes. I also changed the points and installed a petronix ignitor module and 1.5 coil. Needle seems to be bouncing or fluttering a little bit on idle in the tachometer. How do i fix this?