Anatomy of a brazilian tach - contagiro

With the help of our fellow member topolino I was able to score a brazilian tach, the infamous contagiros. Picked it up at the customs office day and started to tear it down.

There's two things I have to take care of:
It's a 4 cylinder version with the 8k scale. I have a 302, though. The original V8 tach only goes up to 6k.
Also, my steering column obviously doesn't have the mouting provisions for the tach. I'll have to fab something myself.

But now for some pictures!

Here's how the unit arrived:


Top part with the glass comes off easily:


It can be taken apart further, now the glass is out:


Two pictures of how it mounts to the column:



Back plate can be unscrewed:


Back view without cover:


Two w5w bulbs:


4 Wires, I believe 12v, ground, light and signal:


Unit itself is screwed in with small gaskets in between:


Back view of the unit, as well as all 4 sides:






Pointer pried off:


Face plate mounted with two tiny screws:


Unit without faceplate:


Mounting cross removed:


Circuit board held on with a plastic retainer:


Circuit board from both sides:



So let's see what there is to do.
I'll have to fab a mount which will make the top of the column look like this, likely i'll cut it out of aluminum:


And now for the delicate problem of calibrating the tach. In the pictures above you can see some sort of poti with the screw secured in place by some enamel. would ford have gone through the trouble of designing two units? Or is it adjustable? That would a giant leap forward.
Otherwise, I'd have to call some friends for help who can actually read these circuit boards. Maybe they can rewire it or change some resistors to amke it work.
If all else fails, I'll get this neat little product:
http://www.technoversions.com/TachMatchHome.html

And please scroll down on this page for some meticulous work on restoring the tach. This guy is not restoring, he's creating pieces of art:
http://www.corcel.blogger.com.br/

If any of you guys have any idea on how to adjust this tach, please chime in.

Topolino, if you can ask someone to get a picture of the inside of a V8 tach, this would help, too - especially this area:

 

Fascinating. Thanks for posting these pics!

 

man, that is nicehow hard is it to get one? i would like to get one for my maverick. thanks russell

 

Thanks for the tour of Brazilian tach innards. Very nice photo documentation.

 

The potentiometer is there for calibrating the tach. Slap it all back together hook it up without the housing, hook up a secondary tach, turn the pot until the two tachs match up.

It should be that simple, but I'd need a cleaner shot of the circuit to be certain.

 

I love how electronics guys can just look at stuff and go "yup ...works like this ..."

My head was hurting as you showed pics of it all coming apart ...

 

It helps that theres only a few styles of tachometer and the automotive tachs work almost identically to industrial equipment of the same vintage.

 

I'm with you Jeff... and we don't have to put it back together...

 

i'm sure i'll get it back together, that's why i took so many pictures.
started by polishing the two plastic pieces:

 

That's awesome how he fixes that trim, I'd like to figure out how to do that.

 

i started on fixing the tach today.
as the steering column is missing the bracket to mount the tach, i fabbed something out of aluminum:






i guess i'll either use glue or two tiny screws to mount the bracket.

after that, i touched up the face plate and the dial a little:


the housing is next, it's already sanded. i guess i'll take apart my dash cluster again to match colours.

 

here's what the tach unit looks with the faceplate and lens:


the empty housing painted and with a new plug:

 

the mounting bracket glued in place:

 

quick electrical check - illumination works. let's hope i figure out 12v switched and signal: