Treb
Treb Reader
10/8/12 7:54 p.m.

So my 1976 Fiat 124 came with a clock in the dash. They break easily and are expensive to fix. The clocks, I mean...

Anyway, I put in an almost-matching Volvo clock from the eighties. It died, too.

So now I have 3 cannisters, 2 veglia gauge faces, 3 sets of clock hands... and I bought a clock from a 91 Mazda 929 off ebay to build a working clock with. The Mazda clock has a big housing, but the actual mechanism is tiny. (The housing and the adjuster mechanism will be under the dash, I think.)

So the Mazda clock has 4 wires. Power, ground, dash lights, and ???

Anybody have an idea, a diagram, or a good grasp of mazda wiring color codes (assuming there are such)?

Thanks for the help. Matt

4g63t
4g63t HalfDork
10/8/12 8:01 p.m.

Constant power ,switched power, ground, lights

pres589
pres589 SuperDork
10/8/12 8:52 p.m.

Why would a clock need switched power?

peter
peter HalfDork
10/8/12 9:13 p.m.
pres589 wrote: Why would a clock need switched power?

Illumination (thus also needing the lights wire).

Run_Away
Run_Away Reader
10/8/12 9:18 p.m.
pres589 wrote: Why would a clock need switched power?

If it didn't have switched power it would be constantly illuminated, and drain the battery (um assuming a digital clock).

pres589
pres589 SuperDork
10/8/12 9:27 p.m.

So what's the light lead doing? Ground is common between the motor and the light, the motor has constant power, the light gets its own varied 0-12VDC+, right?

turbojunker
turbojunker HalfDork
10/8/12 9:34 p.m.

If it's digital the light lead dims the numbers.

Treb
Treb Reader
10/8/12 9:47 p.m.

Not digital. So yeah, I'm wondering what switched power would do, too.

pres589
pres589 SuperDork
10/8/12 9:50 p.m.

I can't find a wiring schematic online in the two minutes I spent looking.

Treb
Treb Reader
10/8/12 9:54 p.m.

Original Fiat clock:

Volvo clock:

Mazda clock:

92CelicaHalfTrac
92CelicaHalfTrac MegaDork
10/8/12 11:31 p.m.

Heh i have one of these clocks too... But now i want a volvo clock.

Treb
Treb Reader
10/9/12 9:39 p.m.

So I googled again for an answer to this question, and the first result... was this thread.

Impressive, Google. Not helpful, but impressive.

Any ideas?

Matt

92CelicaHalfTrac
92CelicaHalfTrac MegaDork
10/9/12 9:43 p.m.

You're probably going to need to dig up the FSM. Might not be easy, there weren't a TON of these things out there.

I'll see what i can find tomorrow.

Treb
Treb Reader
10/9/12 9:50 p.m.

Thanks!

Treb
Treb Reader
10/11/12 5:25 p.m.

So, there are 4 wires into the clock: black, green, brown, and red.

Looking at the circuit board inside the case, where the wires are soldered on, there are some labels.

Black is labeled "GND", which is a good start.

Green is labeled "TNS." Tracing it on the circuit board, it appears to be a ground for the light socket, and possibly nothing else.

Brown is labeled "ILL" which I will hazard a guess stands for illumination, as that trace seems to head to the bulb socket on the circuit board. (I checked them as far as the socket with a voltage meter/continuity tester.)

The red wire is labeled "B"

B appears to connect to a resistor, which then leads... well, elsewhere on the board. My first guess would be B as 12v positive, unswitched, and leave TNS and ILL unattached, as I won't be using the light socket on the board.

Any warnings/better ideas, or reasons that the light would have its own ground?

Thanks

Matt

93gsxturbo
93gsxturbo Dork
10/11/12 5:56 p.m.

The light may have its own ground if its wired up like Autometer gauges. The light snaps into a plastic housing, cant ground though the plastic housing, and therefore needs its own ground.

The B+ and other ground are for the clock. Easy way to test, put an ohm meter across the suspected light leads, should read very close to 0 resistance. Pull the bulb out. Should read infinite resistance (open).

93gsxturbo
93gsxturbo Dork
10/11/12 5:57 p.m.

Have you looked at the Autometer clock options?

http://www.autometer.com/search_results.aspx?q=clock

Treb
Treb Reader
10/11/12 7:54 p.m.

I looked through the autometer things, and some of them might be close-ish.

But my wife took one of the fiat clocks to an alleged clock repair shop here in town, and he massacred it. So I already have a Fiat case, hands, and face, with the mechanism out. If that's not crying out to be an ill-advised, unnecessarily complex project, I don't know what is.

Matt

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