Tach issue. Pic Request

[Lynn]

Is that small brass screw in the blue part an adjustment?

Anyone know?

Haven't heard back from Greg (the seller) yet.

[mssl72]

That appears to be a variable resistor. Probably for calibrating the movement.

[HawkX66]

Originally Posted by Lynn

Nice pics Dave.

I bought the same kit. Posted this on TC earlier today.

I recently purchased a new circuit board from Greg on ebay: $25 and free shipping. What a deal: https://www.ebay.com/itm/NEW-69-77-G...53.m2749.l2649

I swapped it out last night. The only thing I want to point out is that I had to gently squeeze all of the female bullet connectors to insure a tight fit on the new board. Other than that, install was very straight forward.

Started the car to make sure the tach worked (it did) and then finished putting things back together. For you slim dextrous guys, you might be able to pull the tach without pulling the radio, but not me. To pull the radio, I had to pull the add on gauges below the radio, meaining I had to put all that back together. Not a big deal, but just 9 weeks after a reverse total shoulder joint replacement, not a pleasant task.

Came home from work early today and took the car for a drive. Had a blast. Burnt some rubber (at least one perk of the insane covid-19 restrictions is that there is less traffic). But, my tach reads even HIGHER than it did before. I sent Greg a message asking what to do. I suspect he will advise that I send him the tach for repair.

I did notice that on the white wire going to the circuit board, there is an in line resistor. I assume that is the resistor that gets replaced by the "adjustable" resistor referred to in the bulliten.

Anyone do this? Of course, I can send it in, but come on. I do almost EVERYTHING myself on my cars. There has to be a way to get this done.

Originally Posted by Lynn

Is that small brass screw in the blue part an adjustment?

Anyone know?

Haven't heard back from Greg (the seller) yet.

It sounds like he didn't calibrate it correctly. Yes, the brass screw on the blue plastic part (variable potentiometer) is how it gets calibrated. You have to tell them what your red line is. Thankfully mine seems to be spot on. I've put several hundred miles on since I installed the new board.
I don't know if I'd send your tach in. If he doesn't get back to you in reasonable time, I'd buy another board from another vendor. It seems like you'd be paying the purchase price in shipping back and forth.
edit: I was just thinking... Are you sure it wasn't off before? Is it starting at zero? My guess is Greg will get back to you and that he just has something going on right now. He was pretty attentive with me. I still wouldn't send my tach. That's just me though. It sounds like you're the same...