The pots are for calibration. One calibrates the high range, the other calibrates the low range. The 89-later tachs have two pots, and the 87-88 tachs only have a single adjustment pot.
Calibration method using the pots is in the video up above.
What caught my eye is the traces that are bridges marked “cyl”. My tach doesn’t have that. I wonder if desoldering it changes it to a v8 version. Would need to see a 90-93 v8 tach and see if that is soldered together.
Calibration method using the pots is in the video up above.
What caught my eye is the traces that are bridges marked “cyl”. My tach doesn’t have that. I wonder if desoldering it changes it to a v8 version. Would need to see a 90-93 v8 tach and see if that is soldered together.