Guys, I have had this Dixco Model 97 Tach for quite a while and I have been saving it for just the right car even though I don't know if it actually works or not. Well I finally have the right car and I would like to use it so I have been checking it out. When I would handle the tach and turn it over in my hands I could hear that there was something loose inside. I disassembled to the level shown in the pictures and there was a curved copper plate, about 1/2" x 3/4" long with a hole in it, loose inside the tach. I removed it and then with a flashlight looked down inside the tach to see if I could figure out where it belongs. As I was doing this I also noticed what appears to be a loose, unconnected wire with an "L" shaped terminal on the end laying down inside the tach. If you look down in the center hole of the tach in the picture where I am holding up the masking tape with an X-acto knife, you can vaguely see the wire laying down on the backside of the tach face. I was able to carefully grab the terminal and pull it up through the center hole so that you can see it in another picture. I Googled for assembly drawings or diagrams for these tachs and couldn't find anything so I am hoping that someone here has been deep inside one of these tachs before and can help me with some questions. Does anyone know what the copper piece is for, or where it goes, or if it is even part of the tach? How about the wire? Where does it terminate inside the tach? Does it? Does anyone know how to further disassemble this tach so that I can reconnect the wire if I need to? Let me know if you can help a brother out. I am sentimentally attached to this tach and I would like to save it if I can.
A couple of years ago, when we were trying to come up with a generic controller box for "meter" type tachs, we had a Dixco as one of our "guinea pigs". Although that project never worked out (too much difference between different makes of tachometers), my partner picked up some knowledge on them. I will talk to him over the next couple of days to see if he has any insight into this. May I ask; how many wires are there coming out of the tachometer head? And what are their colors? While we're at it, how about a picture of the face?
There are a few threads here about these tachs, one of them is mine. I can only point you to those. I have one in my 55. Good luck.
tubman, It is a 3 wire tach - black, white, and green. I will try to get a picture of the face later today, but it is an 8K tach with the blue line.
It's probably a newer "motor" tach that doesn't need a controller box. The green wire is usually the impulse from the distributor, white is probably positive power, and black is ground. (Newer tachs usually have 4 wires, the fourth being separate power for the light). I showed the pictures to my partner, and they didn't look familiar to him, so that's about all I can tell you, as we were concerned only with the older meter tachs..
I don't know but that quarter is too new for this thread. . Seriously though, If you don't mind spending some bucks on that tach, is there anywhere around there you could take it and get it serviced?
Found this from the HAMB from several years ago... Dixco Tach Wiring. Discussion in 'The Hokey Ass Message Board' started by dlotraf, Apr 1, 2012. Watch Thread dlotraf Member from Georgetown, Texas I searched through several older threads on Dixco tach, looking for a schematic for the internal wiring, and discovered many guess's and incorrect methods for wiring these tach's. So here it is. 60's (at least) Dixco tach's have three wires. I have three a model 97, a 3-5665 (which was made for NAPA) and a late 60's which at this moment I do not have the number handy. All three have three wires. Black, White, Green. Correctly wired Green - Sender to - (neg) side of coil, or tach terminal on a HEI dist. White - Ground Black - + to either + side of coil, or ignition terminal from Ign switch. No one seams to understand the lack of a red wire, and most want to use white for red. Modern tachs use 4 wires, one red. Actually it is perfectly logical if you are used to working on the electrics of older cars. In the 50's and 60's I know for sure, Black was mostly used as a Hot Color. I recently studied 50's and 60's Ford and Chevy wiring diagrams and very little (if any) red wires were used. Also Green was rarely a ground. Black was mostly if not always a hot color. Another tidbit if the bulb is bad on one of these 3 wire tachs, it either will not work or read incorrectly. If you unhook the ground it will work, (may not read correctly). My guess is it picks up a ground from bad bulb or may be a back feed. With ground hooked up won't work at all or reads really low. I discovered this today on that NAPA blue line tach. Someone tore it apart and pulled wires loose from board. I finally found a fuzzy picture here and was able to rewire it. So since in my searches I found more questions than answers on the correct hook up of these tach's I thought I'd pass it along. Also None of the Dixco tachs I have ever found require a sending unit. If they don't work when hooked up this way, some componet is bad. Just remember if no light operates, put a bulb in before you tear it apart, or condemn it to the neat, (but non functional) parts shelf. Hope this helps someone out.
RE : the post by "Bob Lowry" above. It has a section about wiring which says : Correctly wired Green - Sender to - (neg) side of coil, or tach terminal on a HEI dist. White - Ground Black - + to either + side of coil, or ignition terminal from Ign switch. This may be correct for a Dixco, but for just about all other modern tachs, black is ground, red is tach power, and white is light power. I am no expert on Dixco's, but given this convention, I would double check everything before I hooked it up and tried it. There may be a polarity marked some place (maybe on the circuit board or stamped into the case). It is something to consider.
Looks like a Dixco can be run positive or negative ground, which explains the confusion on the color codes of the wires. I have never seen a unit that will do that before. You learn something every day.
@Thor1 This is just a guess. I don’t see a bulb socket. Maybe the loose wire connects to the missing socket and the copper piece could also be associated with the bulb. While reading through some of the posts I noticed some said theirs didn’t come with a bulb.
Did anyone ever figure out what the copper piece is or where it is supposed to go? I just received a Dixco in the mail that I bought off ebay. Was supposedly working when removed. I noticed a rattle in it and took the housing off to find that (inside the clear internal electronics housing) I have the exact same looking piece, loose in my tach.
Glen, No, I never heard anything on it. It's funny, I was just looking at that piece the other day and then your post came up... Steve
Has anyone here solved any of the problems? I just got two of these, Model 97s. One originally had two resistors and one has been removed to work on a 6 cyl. It sorta does. It seems pretty close at idle and up to 2000 or so. Won't indicate over 4000 when I know the the engine is turning around 5000. I haven't checked the bulb and that will be next. This is the same action the seller described when he tested in on a V8. It looks like the other one came with three resistors and one has been removed. Some of the ones I've seen pictures of came with 3 resistors and had red & blue. Remove red for six cylinder remove blue for four cylinder . This one does not have a red or blue but I suspect the blue was removed but the seller said he tested it and it worked on a V8. I haven't tested this one yet. I wonder if using pictures and color codes from threads here if the right resistors can be found to replace ones that have been removed to restore these tachs to the original default settings? Also can the other components be tested individually? Would these be sensitave to wire size? Should they be fused?
I took the one that sorta works apart today. The light is in a socket. There is no big copper piece in anything that comes apart as far as I am willing to go. I took pictures and need to do some editing then I'll post thumbnails. I'll write down all the part numbers I can see and maybe draw a schematic of the circuit board. The circuit board wiring makes no sense to me. It looks like everything goes to a ground somewhere. I guess it has to to complete a circuit. Two metal washers on the two main posts contact wires on the board. I don't see where anything signal goes beyond the circuitboard unless the screws that hold everything are part of the circuit. There is at least one black wire soldered to something by the needle in the part I can't get out of the case. When I pulled the tape off the second hole and saw what looks like an adjusting point I quit. The bulb looks good but I'll test it and then put it back together and give it another try just for kicks. One thing cool is that the two main posts, which thinking about have to transmit the signal, are all the the cylinder selecting resistors connect to. Is if the resistors can be identified switching to 4-6-8 cylinders would be easy. If anyone cares.
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