I am digging back about 60 years into the cobwebs in my mind. I'm among other things a retired electrical engineer and held a 1st radiotelephone license back then. That has some "interesting" wiring - close to haywire... Bottom center looks like a bayonet light bulb. The red wire is soldered to the center conductor a light bulb. Guess that is +12 Volts The black wire is soldered to the base of the light bulb. Guess that is Ground. The white wire is the only other wire. Guess that is the tach input signal (Usually the points connection at the ignition coil. The tach is "reading" the opening and closing of the points). Note; These inexpensive tachs were sold for use with 4, 6 or 8 cylinders. Look at the 3 resistors soldered between the meter posts. One resistor has a splash of red paint and one resistor has a splash of blue paint. Setting your tach for the cylinder count involved cutting 1 or more of these resistors out of the circuit I vaguely remember installing an inexpensive tach in the late 1960's (Somewhat better built than this one - I think it had a printed circuit board). The instructions called for cutting different colored jumper wires for different cylinder counts. Try installing it without cutting any wires - I "think" that the default is 8 cylinder. Good luck, Russ
EDIT: To be honest, I didn't even realize I was looking at the backside of a light bulb (where the red wire is soldered). That brings up a question...If the bulb happens to be bad or goes bad, does that involve further disassembly than shown in the pic, and/or soldering, to replace the bulb? Input greatly appreciated, Russ. Yes, I have installed them years ago, where you removed one or both resistors (or none), depending on cylinder count. As far as the quality of this piece, I wouldn't have a clue what I was looking at, no more than I knew which wire went where. Figured I'd simply look up "Dixco tach wiring",and got thrown for a loop with the red wire/lack of green wire. I just knew it had the look I was after for my 31 Chevy coupe traditional hot rod build. Hopefully I can get it working when it arrives. Thanks again for your knowledge, Glen
I've stared long and hard at that backside picture. I am "guessing" that the red 12 Volt wire only powers the light bulb. Further guess that the tach meter movement is drawing power from the "ON/OFF" signal measured at the ignition coil "+" terminal. No fancy transistors or integrated circuits involved. Russ
I would assume, as you surmised, the white wire would be the "trigger" wire, which would go to the - side of the coil, correct? Are you saying the red wire should go to the + side of the coil, as well? I also assume it could go to any switched 12v+ source too, and serve the same function-lighting the bulb? Thanks, Glen
Update: I hooked this tach up (to an HEI ignition equipped truck). It did not work. I assume these tachs will work with HEI? I'm now wondering what role the copper piece plays, where it goes etc. The clear housing (that this copper piece is laying loosely in) seems fairly tightly sealed up, and I hate to break it apart further without having an idea what I'm looking at/for in regard to this copper plate. I'm guessing it served some purpose though, and likely why this thing doesn't work. I should probably give it up and stick it on a shelf, it would just look cool in my traditional style hot rod build.
That tachometer was built long before HEI was invented. I suspect that the tachometer output signal of the HEI is not compatible. p.s. Any capacitors in that tachometer may have dried out - causing the tach to not work.
I am a lucky guy....on Friday at a garage sale I picked up a Dixco tach for $5 and wondered about a wiring diagram and the answer appears a couple of days later with no search on my part It will be interesting to see if it works.
And here is an additional link from the Hamb... Dixco Tach Wiring. | The H.A.M.B. (jalopyjournal.com)
Seems like I can use this information for my Balkamp 3-5665. Only thing is that the wires are different, blue, red, and black.
The Jalopy Journal
