240Z Tach topping out to 8K whenever key is on

[1973240]

same boat. same problem. does anyone know how to rebuild it at home instead of sending it out? that link looked really cool but would that work with a tach thats already fried? does anyone know what part if the tach goes bad when this happens?

[chocolate_supra]

Get this- I got the tachometer unit out of the enclosure and found that one of the internal wires coming off a resistor was contacting the case! Nothing on the unit looks cooked at all, it actually looks pretty fresh. So we carefully bent the wire away from the case, put it back together and reinstalled the tach in the dash and when I'm done with my firewall insulation we'll stick the dash back in and I'll let yall know if I got lucky with this or not.

Picture is of a modified tach, but the wire in question is still present where I highlighted it. As a matter of fact, it looks bent in this picture about the same way mine was.