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Discussion Starter #1
The tachometer on my 84 Spider does not show the correct RPM value. With an external tack, it idles about 850 RPM, but the tach registers 1400 RPM at idle.
In putting the dash back together from the restoration, I double checked all ground wires and everything appears to be correct.
Any suggestions? Is there a way to tweak the tach or calibrate it.

Thanks!
Les
 

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Discussion Starter #3
Thanks Bob,
My 84 does not have the monopod. Do you know if this holds true for this style of tachometer?

Les
 

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Discussion Starter #6
Thanks for the post, I'll start with replacing the capacitors. Seems everyone's issues are the tachometer reads low, while mine is almost 600+ too high at idle.
Les
 

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But Mad North-Northwest
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If it's not the caps it's the potentiometer. My speedo guy said that Alfa used crappy pots that go bad over time. When he calibrated my instruments he replaced the pots and they've been rock solid ever since.
 

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Guys... its both.

Everything but the circuit board is suspect. These tachs are now 36-29 years old. I'd everything I can find while its open. When I did mine, I purchased all the components online (either ebay or amazon). If anyone is interested in the part numbers for the different caps and pots please PM me and I'll try to point you in the right direction.
 

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Thanks for the great input all, I would personally prefer to send the gauge(s) out for service due to the electronic expertise required.

Does anybody know a good repair shop for Alfa gauges?
 
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