Would anyone happen to have a schematic of the tachometer circuit board (see photo)?

Min appears dead, and considering the cost of replacement I have nothing to lose in trying to fix it.

In the photo, closest to the camera, are three solder pads. One has the end of a diode soldered to it, the pad in the middle usually has the yellow wire (the one to the ignition amp) soldered to it, and the far right pad usually has the other end of the diode soldered to it. I've temporarily removed the diode from one end for testing.

As can be seen, the center and right solder pads are connected (it would appear) by a strip on the circuit board. But there are 380 ohms of resistance between the two pads. If this were a two-sided circuit board, I could imagine that, but it isn't. It appears to be a single-sided board attached to two-sided tape to its mount. I've been unsuccessful it getting the board to separate from either the mount of the tape, and it's fragile enough that it would be easy to break by trying to hard.

Thanks,

John

 

Hi John, I would expect the board to be a frequency to voltage converter.

Is that diode in the picture connected to anything it looks like the RH leg is cut.

First I would test all the components with a DVM if your DVM has diode test function the diode should read about 0.6v one way and nothing the other, with one leg disconnected from the PCB.

If that fails draw the board with all the traces and components and email it to me I will draw up a circuit diagram for you. I've sent you a PM

 

Problem solved I think...misread the color coding on the wiring diagram. Hopefully I didn't damage the tach, will find out tomorrow when I wire it all up.

Thanks,

John