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Tach help.

Discussion in 'The Hokey Ass Message Board' started by HotRodToomer, Oct 14, 2007.

  1. HotRodToomer
    Joined: Jun 25, 2006
    Posts: 857

    HotRodToomer
    ALLIANCE MEMBER

    i tried to wire up the Dixco tac in my truck, came back with a problem.
    now there are only 3 wires, 2 thick, 1 thin, for the thick ones there is a white and a black (power & ground) then the thin is a green (light).
    now i guessed white was power so i hooked it up the the HEI's tac prong. then ground the black, turned it on and nothing. it didnt even move. switched the wires and it was pegged on 8 grand.
    so does this mean my tac is bad or since its so old just not compatable with the HEI?
    thanks guys.
     
  2. i don't think you have enough wires...did you open it up and see if the green wire goes to a light? with white/black being power and ground you don't have a wire for the signal..is there a broke off wire inside?

    i wouldn't hook ANY power wire the the TACH terminal on the HEI
     
  3. HotRodToomer
    Joined: Jun 25, 2006
    Posts: 857

    HotRodToomer
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    so the white is power, the black ground and the green signal.
    seems easy enough.
    much apreciated.
     
  4. HotRodToomer
    Joined: Jun 25, 2006
    Posts: 857

    HotRodToomer
    ALLIANCE MEMBER

    Ok so that didnt work.

    hooked the white to power, grounded the black & hooked the green up to the distrib. now it twitched when the key came on then when i started the truck it went right to peg at 8 grand.
    i took it apart and i see nothing wrong, no extra wires, no missing wires, nothing wrong but just the fact it will not work.
    any ideas?
     

  5. squirrel
    Joined: Sep 23, 2004
    Posts: 48,682

    squirrel
    Member

    Houses use white and black for power, but cars usually don't :)

    Can you take a picture of the insides, especially where the wires connect?
     
  6. My old s/w stage 1 tach only had three wires too, two went to the coil and one for ground. The light comes on right away when you turn the ignition on but the tach would not function wired differently.
     
  7. HotRodToomer
    Joined: Jun 25, 2006
    Posts: 857

    HotRodToomer
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    i sure will get some pictures today for you.
    its pretty simple inside, just a lot of resistors.

    lBB41, i have HEI, if two of the wires are supposed to go to the coil, should i just run them together and plug them into the TACH port on the HEI top?

    if it helps its a 'Dixco' tach part of the 'Dixson' parts devision.
     
  8. SinisterCustom
    Joined: Feb 18, 2004
    Posts: 8,269

    SinisterCustom
    Member

    The green wire always goes to the (-) side of coil...or the TACH term. on HEI. If your Tach pegged the needle at startup, check the inside for a switch to select from 4-6-8 cyl......it sounds like its set for the wrong # of cyl.
    Generally tachs have 4 wires. Green=tach, black=ground, red=power(ign), white=internal light.
     
  9. HotRodToomer
    Joined: Jun 25, 2006
    Posts: 857

    HotRodToomer
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    it has the number of cylender deal on the outside, there are 2 resistors and a tag that reads, "For 6-Cyl engines remove Bottom (Red) resistor"
    ill get pictures when i get home today, for together to compleatly stripped.
     
  10. SinisterCustom
    Joined: Feb 18, 2004
    Posts: 8,269

    SinisterCustom
    Member

    Yep.....your tach may be old enough to not have a selection for a 4 cyl... Is the red resistor still there??? If so, maybe it's fried? If so, Radio Shack or a specialty electronics store (not Best Buy, etc.) should have one. They can match it up by the colored band sequence on the resistor.
     
  11. Django
    Joined: Nov 15, 2002
    Posts: 10,196

    Django
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    from Chicago

    Did the light ever turn on?
     
  12. Mr T body
    Joined: Nov 2, 2005
    Posts: 2,189

    Mr T body
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    from SoCal

    The correct hookup for Dixco tachs with 3 wires is:

    Red - connect to a switched ignition source, positive (+).
    Black - connect to ground (-).
    Green - connect to the coil's negative (-) terminal.

    Sounds like you have an internal problem... happens with age:(
     
  13. Django
    Joined: Nov 15, 2002
    Posts: 10,196

    Django
    Member
    from Chicago

    He doesn't have a red wire.
     
  14. Mr T body
    Joined: Nov 2, 2005
    Posts: 2,189

    Mr T body
    Alliance Vendor
    from SoCal

    I cut and paste from a Dixco instruction sheet without editting. :eek:
    I don't have any Dixcos where I am now to check, but can check later today. Is the back similar to one of these two, and does the paper tag still show the model#? Both these had red power leads, but typically the green is signal, black is ground, and through the process of elimination, the white is your power (+) lead.
     

    Attached Files:

  15. HotRodToomer
    Joined: Jun 25, 2006
    Posts: 857

    HotRodToomer
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    model number is 97.
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  16. Mr T body
    Joined: Nov 2, 2005
    Posts: 2,189

    Mr T body
    Alliance Vendor
    from SoCal

    I checked my Dixcos and they are all either black, red and green, or black red, and white. I took one of the 97's apart, and the board is different than yours, so I can't tell you for sure that your white wire is the (+), but if I was a bettin' man....
    You don't need an adapter unless you're running a DIS ignition, so it still sounds like you have an internal problem. :(
     
  17. redracer64
    Joined: Aug 8, 2005
    Posts: 27

    redracer64
    Member

    I also have a couple of dixco tachs that I can't fiqure out. one is a model 3-5665 that appears to be the same as the one in this thread. I get nothing what I hook it up but the back lamp. When the green is hooked to the coil it does nothing. The other one I have looks to be a model 97, it is missing the green wire. Does anybody have a 97 that can tell me where the green wire connects in the tach?
     
  18. Mr T body
    Joined: Nov 2, 2005
    Posts: 2,189

    Mr T body
    Alliance Vendor
    from SoCal

    Remove the back and take a pic of the board and (hopefully) I can match it up to a board I have. Is your 97 a blueline?
     
  19. redracer64
    Joined: Aug 8, 2005
    Posts: 27

    redracer64
    Member

    Here are some pics of the inside and outside of the tach that is missing the green wire.
     

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  20. redracer64
    Joined: Aug 8, 2005
    Posts: 27

    redracer64
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  21. redracer64
    Joined: Aug 8, 2005
    Posts: 27

    redracer64
    Member

  22. Mr T body
    Joined: Nov 2, 2005
    Posts: 2,189

    Mr T body
    Alliance Vendor
    from SoCal

    Here are 2 boards I looked at this morning. Although the boards are different in appearance, the circuits appear to be similar. Hope this helps.
     

    Attached Files:

  23. redracer64
    Joined: Aug 8, 2005
    Posts: 27

    redracer64
    Member

    thanks that sure does.
     
  24. jwesslen
    Joined: Dec 3, 2009
    Posts: 8

    jwesslen
    Member
    from Sweden

    I have a Dixco Blue Line 10k tach where all the wires have come loose from the circuit board. Anyone have a photo of which wires go where on the circuit board?
    There is a Power and Ground (?) coming from inside the tach and then one wire from ground of the housing and one wire from the lamp, that far I am OK but then some or all of the should attach somewhere on the circuit board and there I am lost!
    Thanks, /Johan
     
  25. jwesslen
    Joined: Dec 3, 2009
    Posts: 8

    jwesslen
    Member
    from Sweden

    Trial and error... then I managed to get it to work. Realised I missed one of the resistors that goes on the back of the board so when I figuured out the value of that one it all fell in place.
     

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