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Cars > pwrcat4000’s Garage > Blog > Tackling the Tach


pwrcat4000’s Profile Photo


M –50
Hutchinson, Kansas
United States


pwrcat4000’s Blog Posts 1 – 5 of 27

Sat May 18, 2013  |  1 comment
updated some of the info
Thu Mar 8, 2012  |  comment
TACHling the TACH The tach is back!
Mon Mar 26, 2012  |  comment
Tachling the TACH Mental Lapse
Mon Nov 14, 2011  |  comment
Tackling the Tach
Wed Nov 2, 2011  |  comment

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Tackling the Tach

By pwrcat4000

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Well tonight I started working on the small stuff as my Body work is stalled right now until I teach my self to weld sheet metal.
My tachometer had been working until after the engine rebuild then it failed. I was unsure if it was wiring or the actual 35 year old tachometer, as you all know I have no money at all so I am forced to try and fix things on my own. If you have the cash
Option #1 this is the best way to go They come highly recommended and were only going to charge a little under $180.00 plus shipping both ways.

Option #2 Here is another way to go BRAND NEW $289.00

I chose option 3 fix it myself. I recently acquired a broken 50 inch plasma screen some one gave it to me and said "it wont turn on and its out of warranty I bought a new one you want it?" I was able to fix it as it was just the power supply and needed about 8 $0.25 capacitors paid a guy to solder them in and Walla! $60 50" HD plasma screen. I may be pretty dumb but I can read and learn on occasion.

So... here is what I have done.
First got the clock working luckily I have a 12V power source so I know it works now I followed Gold78Spc instructions to a T (/A) LOL. they are here although I used WD40 not 3-1 oil and did not clean the contacts It is keeping time about as good as a non Quartz clock from 1977 does, I'm told. It has been hooked up for about 5 hours now and has not lost or gained time. You can update it to Quartz movement the same people who are in Option #1 above (as a matter of fact they can fix all the gauges, calibrate them, and reface them ect.)
Second I disassembled and removed the circuit board out of the Tachometer. I don't have the skill or equipment to test this board so I am going down to the electronics store (where I bought those capacitors for the TV) tomorrow to beg for help. I suspect the Radial Film Capacitor is to blame that is the thing that looks like a cigarette but (they use them in guitars too according to google). Hopefully he can get the Circuit working or sell me the parts and I will take it to the guy I had fix my TV board.
So You are probably wondering how I know this is the problem with no electronics tools. Honestly I don't. But here is what I have done to rule out the problem.

Bought a brand new printed circuit for the whole gauge cluster it was about $85.00 mine was shorting against the bezel and I had no interior dash lights.

Bought an after market tach from O'Riley $38.00. plugged it into my tach leads that would be under my dash if it was in the car started the car tach worked so ruled out any wiring /ground issues in the 35 year old wiring. Returned the tach to O'Riley (dont wory they have made a ton aof $ off me) So it has to be the tach. Next took apart the tach as stated above. There were 2 wires hooked to the circuit board in question a white one (+) and a black one (-) the polarity really doesn't mater if you hook it up backwards your tach will try to go backwards. I hooked up a AAA battery to this for a millisecond the needle deflected so that part works the only thing between those wires and the leads from the car is that Circuit board So that has to be the problem.
I will post a follow up when I get the circuit evaluated/fixed.
Hope this helped someone (Lot of typing)

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