Technical speaking of tachometers, Star 2"?

I have had this little Star 2" tach in my stash for a while, again online searches turn up little information on it.
I will be testing it soon to see if anything happens but,
anyone here familiar with these things?
12 volt? negative ground? how many cylinders?
it has the four leads out the back, red, green, black and white and what looks like something meant to adjust.. factory set potentiometer?
any input appreciated

 

Well, white is obviously the light, so that probably conforms to the usual pattern. The probability is overwhelming that it is 12 volt negative ground. (That is, unless there is a corresponding transmitter box that you don't have. Chances of that are slim to none.)

 

Standard aftermarket tachometer wiring is

Red = 12v + switched
Black = Ground -
Green = Negative side of the coil signal
White = Lights

This also applies to rev limiters, RPM switches, shift lights.
And you can connect multiple devices parallel.

So connect it up parallel with another tach to check the accuracy.

 

globe should have voltage and wattage on it

 

I took a look at that link I posted in the other thread to see if they had this one too. No luck.
They do offer service and repair, but have no idea what it costs and how much you value the tach.
If you want to dig in, they do have a number of tech articles on tachs. You could educate yourself on standard designs and practices. With that and a DVOM, you might poke around and find a bad circuit or component.

I tried a few searches trying to find other examples or a company. One was from the 80s to the 90s.
https://opencorporates.com/companies/us_ma/042083501
This is the other, dissolved in the 50s. Both were in MA. Don't know if either are the actual source.
https://www.bizapedia.com/ma/star-gauge-company-inc.html

 

thanks,
that's what I would expect too
12 volt, negative ground, gas engine, point style ignition, common wiring color connections.
if anything happens when connected simple math when compared to trusted tach's numbers should show how many cylinders it was meant for.
just curious if anyone here was familiar with the 2" Star