Clock Power

[roadking77]

Looking through Nuc Envoy's thread about elect gremlins got me to thinking.
Where does the power for the clock come from? The reason being:
The clock has never worked in my 77, nor does the tach as it has yet to be hooked up. I assumed the clock power came from the tach?
However, when I hooked up the battery in the 79 I am working on I was pleasantly surprised to see the clock start to ticking away!  I did not think the tach was hooked up in that car yet either? Maybe it is and I dont know it??

[Wallington]

The 77 vs 79 clock and tacho are both different units internally but believe they are wired up similarly. Tacho is separate to clock, 2 wires, does its own thing. Clock is grounded through the case/rear of tacho mounting plate with an insulated live feed off the circuit board that runs from the main harness plus. There is a ground also through the main harness, doesn't require the strap to the gauge cluster body if the harness is plugged in.

[b_hill_86]

Clock power comes through the large connector on the back of the gauges and through the printed circuit. Separate from the tach.

The 70-78ish clocks are electromechanical. I think I made a post showing the differences between those and the late 78-81 quartz clocks. If not I can post it here later. Anyway, the early clocks usually need one of two things. Either they need lubricated or there’s a set of points that wears out and prevent it from functioning which I don’t believe can be repaired by the average joe. Possibly by a professional clock repairer though.

Tach has its own harness for function separate from the printed circuit

[b_hill_86]

The 77 vs 79 clock and tacho are both different units but believe they are wired up similarly. Tacho is separate, 2 wires, does its own thing. Clock is grounded through the case/rear of tacho mounting plate with an insulated live feed off the circuit board that runs from the main harness plus. There is a ground also through the main harness, doesn't require the strap to the gauge cluster body if the harness is plugged in.

Beat me to it while I was typing lol

[Wallington]

The 77 clock and tacho is available repro in Quartz form, the 79+ type is not. As Brian said, there's kits for the clocks if needed, I don't think the clocks were available new outside of the complete tacho. The components of the clocks are not interchangeable, new or used. They stay with the tacho type, round rear is early, flat sided oval rear is 79+, even if clock doesn't say Quartz. Lettering appeared later to confirm

[b_hill_86]

I did forget to mention there is a quartz conversion available for the electromechanical clocks. I installed one in my 77 before I realized I could get my original working. It keeps good time till it stops randomly. I have to tap my gauge face to get it going again. I’ve heard of a few others having the same issue

[roadking77]

When I restored my 77 I sent my clock out for a restoration service. It was rebuilt as original although he did offer a quartz upgrade, new stem etc. It has never worked, although everything (well almost, no speedo and no tach) else works the clock has never worked?

[b_hill_86]

If you were to remove the cluster you could fairly simply connect power and ground to the clock directly to test

[roadking77]

Didnt think about that, Could I use my battery charger with the positive and negative lead on each post? 
I have used that method before to test other components like the blower motor, window motors etc.

[b_hill_86]

I’m editing my previous post after some thought. Im not sure a charger would be a good idea. Instead, a couple spare wires and alligator clips or something similar with one of your car batteries would work better.

[roadking77]

OK, I will keep that in mind. Its not urgent as the clock has never worked. Being that it was rebuilt I assumed it picked up power from my tach that I knew was not hooked up. IF I ever get the 79 on the road I plan on putting the 77 in the shop for some freshening up.

[Wallington]

I knew I had a copy of the memo somewhere.

Early-June 1978 is the change-over date to the new Quartz clock and matching Tacho often referred to as the '79 type. The early models didn't say Quartz on the faces.

Firebird June 1978 memo for Quartz clock and new tacho by Ben, on Flickr