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Rebuilding & Re-calibrating Neg GND tachs

Discussion in 'Factory Original Alpines & Tigers' started by jumpinjan, Feb 12, 2021.

  1. jumpinjan

    jumpinjan Bronze Level Sponsor

    This is a rebuilt Tiger tachometer with new resistors & caps and so on. To calibrate I used a real coil from a GM LS-2 engine and it's driven by a 5V digital signal provided by my signal generator. The 12V lead to power the coil is the primary winding on the tach, of course. And the coil is firing a spark plug.
    Here's a short video clip of the test on the bench:

  2. alpine_64

    alpine_64 Donation Time

    A mkii Tiger tach... :eek:
  3. jumpinjan

    jumpinjan Bronze Level Sponsor

    LoL! There's a man with a keen eye who knows his tachometers.
    Some tips:
    A little "De-ox-it" contact cleaner on the pot wiper helped a lot. Most all the resistors were out of tolerance. I used Tom H's write-up to get started on this effort. It's best to have a de-soldering gun because of the delicate circuit board material. I have a Kakko 808 de-soldering tool and a Weller WESD51 soldering station.
  4. bernd_st

    bernd_st Bronze Level Sponsor

    Nice set up and video. Can be done much simpler just using a signal generator, but perhaps your bench set is more accurate. Think you know that the instrument needs to be calibrated over the whole range. Tom H. did a lot of good ground work. I'm saying that because I'm also rebuilding tachs over here as a hobby ;)

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