Tachometer Calibration?
Thread Starter
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Tachometer Calibration?
Has anyone disected the instrument cluster to find if there's a calibration adjustment for the tachometer?
Mines has a non-linear error.(reads higher with more needle deflection)
IT's off a couple hundred RPN at 2000 and is around 500 at 5400.
I know most of the circutry is digital and that portion should be ok, but there's an analog converter somewhere in there to drive the tach needle.
Mines has a non-linear error.(reads higher with more needle deflection)
IT's off a couple hundred RPN at 2000 and is around 500 at 5400.
I know most of the circutry is digital and that portion should be ok, but there's an analog converter somewhere in there to drive the tach needle.
Race Director
Joined: Oct 2002
Posts: 13,717
Likes: 5
From: RI
Re: Tachometer Calibration? (VetNutJim)
never taken apart but I bet they removed all the "user" adjustments in leu of fixed 1 % resistance, however I could be wrong.
Your theory is valid though......:)
Your theory is valid though......:)
Thread Starter
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Re: Tachometer Calibration? (VetNutJim)
I suppose the input signal is probably some sort of squarewave.
Even if it's a square + or - pulse that's no problem.
That means I could drive it with a signal generator on the bench and 'adjust' the value of some of those resistors to calibrate the thing. 1% resistors aren't to hard to get, however, I'd rather have a 10% 'correct value' resistor than a 1% incorrect value one.
Arrgggghhhhh !!!! I want this thing to be right. This far off is redicilous.
This one indicates 5500 rpm but Datamaster and Diacom both say 4800.
Mama mia. That's a pretty big err-roar.
I need an OLD one to 'play' with. Don't want to experiment with the only one I got, even if it's not correct. It's not ALL broke, just the tach part.
Even if it's a square + or - pulse that's no problem.
That means I could drive it with a signal generator on the bench and 'adjust' the value of some of those resistors to calibrate the thing. 1% resistors aren't to hard to get, however, I'd rather have a 10% 'correct value' resistor than a 1% incorrect value one.
Arrgggghhhhh !!!! I want this thing to be right. This far off is redicilous.
This one indicates 5500 rpm but Datamaster and Diacom both say 4800.
Mama mia. That's a pretty big err-roar.
I need an OLD one to 'play' with. Don't want to experiment with the only one I got, even if it's not correct. It's not ALL broke, just the tach part.
