2 hours ago, Captain Obvious said:

so you don't bump it or catch it on something and pull more of the PCB trace off the board.

Thats why i gave the advice to put the wire on the component side.. as pro's do.. 

(i've worked with studer revox machines, and ones opened up a TEAC... wow, there are a lot of those wires in there! A ReVox is well engineered.. they don't do/need that!)

Edited December 23, 20195 yr by dutchzcarguy

8 hours ago, Zed Head said:

A service manual would have the diagram.

It is an after market tach from I think 15-20 yrs ago and 510's didn't come with a tach unless it was special ordered.

9 hours ago, Captain Obvious said:

Maybe. Can you post a pic of the other side of that tach board? I can probably tell you which ones are power and ground.

Here you go,

 

From those pics, I believe the black wire is ground side for power.

Can you take the brass hex standoffs off and get a shot of the back side of the board? Is there enough slack in the tether wires connecting the board to the mechanical portion to spin the board over and get a straight on shot?

3 hours ago, grannyknot said:

It is an after market tach from I think 15-20 yrs ago and 510's didn't come with a tach unless it was special ordered.

The wiring diagram from the car the dash came from would most likely match.  Just saying.  If it was in a car then the diagram is out there.

Red is +12.
Black is ground.
Green is speed input.*
White is gauge illumination lamps.

*Note that I don't know what kind of signal the tach is expecting, but the green wire is where it should occur.

And... The smaller red and black wires leading deeper into the tach are what makes the gauge needle move. I can tell you more about that if there are problems, but I'm hoping it just works and we don't have to.  

Edited December 24, 20195 yr by Captain Obvious
better choice of words. Reduce the obfuscation.

Thanks Bruce, that is a big help.

Glad to help. Hope the project goes smooth.