crazy4offroad
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73-87 Tachometer Repair
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Dr. Paradox
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boy oh boy do I hate working on websites! so confusing!
maybe I just need to organize the files better. oh well. next time
anyway guys, here's the truck version of the page
http://howtoalmanac.com/kevin/projects/automotive/tachfixtruck.htm
give me some constructive criticism here and I can add/change stuff
thanks
-Kevin
maybe I just need to organize the files better. oh well. next time
anyway guys, here's the truck version of the page
http://howtoalmanac.com/kevin/projects/automotive/tachfixtruck.htm
give me some constructive criticism here and I can add/change stuff
thanks
-Kevin
Dr. Paradox
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ok, wow that one sure is different..... are there other gauges connected to this board? it seems like there is a bunch of extra stuff
crazy4offroad
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No extra gauges. I dont know exactly what year truck this one came from either. The problem is it reads high with ignition off, ignition on it goes up a little more, and truck running it goes up to about 2500 rpms and is unresponsive to throttle. When I first started checking it out I noticed the (+) trace was burnt and hanging off the board. I stripped it the rest of the way off and soldered in the jumper wire to the first connection but of course that was not going to fix it.
By the way I checked out your site, and the instructions for adding the pot switch semms very well done! Clear and understandable, for me at least.
By the way I checked out your site, and the instructions for adding the pot switch semms very well done! Clear and understandable, for me at least.
Dr. Paradox
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the way these tachs work with the sine and cosine coils, it will seek a home position no matter where it was.
what happens if you move the pointer to several different places and power it up.
does it always seek to the same place?
what happens if you move the pointer to several different places and power it up.
does it always seek to the same place?
crazy4offroad
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Yes it does, powered up or powered down, running or not.
Dr. Paradox
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wait, so it acts like it has a spring and returns to the same position when it's not connected to anything?
crazy4offroad
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Not really like a spring. Like a gradual slow movement, pretty close to wherever it was sitting before you move it.
Dr. Paradox
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I almost wonder if someone stuck the wrong gauge on this board.
mine would stay anywhere you put it. but it would shoot right to 0 when you hooked power up to it.
yours does seem to have another resistor chip and a bunch of transistors that mine didn't have.
I'll keep researching this, it seems like your tach is a lot different
mine would stay anywhere you put it. but it would shoot right to 0 when you hooked power up to it.
yours does seem to have another resistor chip and a bunch of transistors that mine didn't have.
I'll keep researching this, it seems like your tach is a lot different
crazy4offroad
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Thanks Kevin. I was almost to the point of giving up on it. I still have a Camaro tach I may try to graft into the cluster, others have done it. Also considered gutting an aftermarket tach with a similar sweep and range and put it on the factory face. If I remember correctly you may be right about it staying wherever when it is off, but when powered on it would go kind of slowly to 1500 rpms. When started it would go up to 2500 and unresponsive to throttle. Moving the needle by hand when powered/running it would slowly drift back where it was before moving it. Anyway, I'll put all that on the back burner for now and concentrate on the trans build.
Dr. Paradox
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ok, it definitely sounds like something is funny with that tach. in the mean time you could just keep an eye out for one like Tony's. internet, junkyard or something. it seems like it would be a direct fit, but has the newer circuit board that we know how to fix! haha
always more complicated than the last one.
good luck with the transmission! I'll probably be doing that soon too
something else to keep in mind, this tach is probably for points ignition?
are you running points or HEI or aftermarket? it could just be very confused or could have been damaged by a different ignition system
always more complicated than the last one.
good luck with the transmission! I'll probably be doing that soon too
something else to keep in mind, this tach is probably for points ignition?
are you running points or HEI or aftermarket? it could just be very confused or could have been damaged by a different ignition system
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TPISly-C10
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75gmck25
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There are several sources for Corvette restoration tach boards, but I’ve never found one for our squarebody tachs. Looking at pictures, the shape of our tach boards is completely different than the Corvette, so you couldn’t easily reuse one.
TPISly-C10
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they all the same tech and purpose to all GM in this era...only the board change of form and fit....even see a guy retro fit a ford tach board on is gm 
AuroraGirl
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then why cant youthey all the same tech and purpose to all GM in this era...only the board change of form and fit....even see a guy retro fit a ford tach board on is gm
I wouldnt say ALL because unless they all used the same AC signal that was gotten from a flywheel sensor or alternator(whatever it was they used) and that was the same as the HEI tach signal, (isnt it driven off the camshaft?)
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