Clock Repair: Analog, 70-78 Z (Round)

[EScanlon]

This comes up often enough that it should be posted as a tech article. This is taken from a different posting where Heater Control Panel Illumination was the topic.

In case that is what you were looking for:

(Original Thread: http://www.classiczcars.com/forums/showthread.php?p=141090#post141090)

The Clock not working in the Z's is such an endemic characteristic that it almost seems a basic requirement of the car. If your clock works....it's not a Z.

Fortunately, with a little careful effort it can be avoided. Here's how:

......snipped from original thread....

As far as your clock, you can fix it, and if you're careful it will last a long while. I fixed a pair of these a couple of years ago and they're still working great. I even went the extra step to calibrate it and now it only gains 1-2 minutes a day. Not a chronometer but definitely much better than not working.

Open the clock housing by removing the two screws holding the face bezel in place. Next gently lift off the clock hands, and carefully remove the face. Below it you should find a black washer and a spring tripod washer. Make sure you don't lose these. Once these are off you can address the main problem with the clock.

Added on edit: The sequence of these parts from outside in: Bezel, Minute Hand, Hour Hand, Clock Face, Black Washer, Tripod Washer.)

From the back of the case, ( * see add )remove the 3 nuts that hold the clock mechanism inside the case. Once this is done, carefully force the wire and the rubber boot that powers it, INTO the case, and then do the same thing for the connector. If your connector boot (not the one at the case, but the one where the clock connects to the harness) is pliable enough, gently straighten it out and fold in the heat crimped plastic wings so that it will fit through the hole in the case.

Added on edit: The bracket that holds the clock to the dash and fits the outside of the case needs to be removed first. There is also a "newer" clock version where the 3 nuts holding the clock mechanism aren't on the back of the case and the bracket that attaches to the case and dash doesn't have the extended "handle". Be careful opening these as EVERYTHING inside pops out the minute you remove the bezel.

At this point you should be able to remove the clock mechanism from the metal case.

Take a minute to clean out any dust or gunk inside the case, and if you want it to be brighter when illuminated, paint the inside with a WHITE paint, the green lens on the bulb housing will still illuminate the inside as green, but it will be MUCH brighter when you have the lights on. Be careful not to smear the bulb housing. Set this aside to dry.

Now, looking at the clock mechanism. You'll note a little motor on the back side of the mechanism. ( * see add ) Get a bottle of sewing machine oil and a long enough needle and apply a small drop (by small, I mean minuscule) to the motor housing and the associated pivot points. You can power it up right away, although personally I let this soak for a bit. Usually the length of time to let the paint dry in the case is sufficient, or overnight.

Added on edit: The newer clocks mentioned before have the motor OPEN and with the shaft of the motor being the PENDULUM of the clock. The earlier clocks had a standard clock pendulum but used the motor to WIND the clock spring. The oiling procedures for both are nominally the same.

Next, to ensure that it's working, you can either re-assemble and plug in, or you can provide power to the clock via a 12v power supply. It doesn't require a large current as the motor just winds the spring enough to keep the clock going. If everything is working correctly, you should hear and see the motor wind and you'll notice the pendulum gear begin to oscillate back and forth. I then re-assemble the clock and to ensure it doesn't conk out, I leave it plugged into the power supply for a while.

If you want at this point you could calibrate the clock, except for one thing. Most power supplies supply 12.0v DC, while in the car you will be working with 12.8v to 13.5v depending on the condition of your battery and connections. To get it "perfect" you would need to match the voltage in your car. This takes a l o n g time, so leaving it in the car would be a problem, unless you don't mind having it dangling off on the side for days-weeks. So, if you don't mind it running a bit fast (as mine does), just hook it up to your power supply continuously for a few days.

The procedure is simple.

Once the clock is functioning properly, set the time to match a KNOWN good clock. Whether it's your wrist watch, a house clock, digital or analog it doesn't matter. You're just going to be using it to compare what the car clock is doing in relation to that one.

After 24 hours or thereabouts as it doesn't matter whether you check every 2 hours or 200 hours, compare the time on both pieces. If the car clock shows 12:30 and your reference is 12:00, the car clock is fast, the opposite would be a slow mechanism.

On the back of the clock housing, you'll notice a hole, usually with a milky white plug inserted into it, with markings around it ( + | | | - ).

Added on edit: The newer clock has ( S <----> F ) with the arrow ABOVE the hole while some older models had ( F <----> S ) with the arrow BELOW the hole. The directions are the same, but it's easy to think they're reversed.

Remove the plug, and inserting a small straight screwdriver into this hole, you'll find a screw in there. Give it a gentle twist in the direction you need to adjust the clock. If fast, tweak the screw by a DEGREE or two (360° in a complete revolution) in the - direction. If slow, in the +. Be careful not to over-adjust, a small adjustment of a degree can be as much / little as 10 minutes per 12 hours or less, so by doing small adjustments you won't swing erratically all over the place.

Reset the car clock to coincide with the reference clock. Recheck the two clocks again in another day or so, and repeat the adjustment until they coincide with each other, or you are satisfied with the amount of disparity.

Hope this helps.

Enrique

This post has been promoted to an article

[xray]

Enrique:

Your timing (ooo, no pun intended) couldn't be better! I sat at my kitchen table not two weeks ago with a screw driver in one hand and my clock in the other wondering how the ^&%&$ I was gonna get my clock to work...Now I have a plan!

PS: are you compiling these tech articles for a book? If not, you should consider it.

Steve

[EScanlon]

We're pleased to aim!

Well, it's kind of hard to get people to pay for what I've already given away for free. Heck, in that light, I might have someone looking for me because I gave it away....hmm!!!

The big advantage to having them here is that it draws people to the website. Hopefully they'll buy a CD, T-Shirt, Cap, subscribe to Sport Z magazine or any activity, but you get the drift. That's why I do them here. I used to post at other sites, but not any more.

Can't claim to be another Wick Humble, nor Mark Twain, but hopefully it helps another Z owner to keep his vehicle looking sharp.

Replies such as yours are sometimes all I get, and that makes it worth it.

So THANKS!!! (I don't think there's a "hug" emoticon, and we wouldn't want Bill (Fun in my Z) getting ideas, otherwise consider it here.)

Enrique

[xray]

Well......

If it comes in a cool binder with neat photos, I'd pay for it. Or even on CD...give it some thought.

Keep it up!

Steve

[Alfadog]

Excellent! I will try this on my C110 clock, which I guess would be similar enough.

[g72s20]

Excellent! I will try this on my C110 clock, which I guess would be similar enough.

How did you go? Did you get it to work? I now have two that have stopped!

[Arne]

I did the one out of my parts car today. It's been running for over two and a half hours now, a new record for me and Z clocks!

I took some pictures when I did it, so I thought I'd add them as visual aides. The file names are descriptive.

[beandip]

Ok , Ok , Now You Have Done It ! E. Is Going To Need A Larger Hat Size Now .

[Alfadog]

How did you go? Did you get it to work? I now have two that have stopped!

Oops, sorry, must have missed this. I had a fairly quick try at getting the clock cover apart, but couldn't. So I tried a spare clock I had and it worked, albeit slowly. Adjusted the speed with the controller on the back and now I have a working clock! It's a smidge too slow, I need to wind it forward about 5 minutes every week. But I'm happy with that.

[monkeyman]

I was stuffing around with a few Z clocks and found there were mostly two types. The one described above, and the one in my 260Z (a Kanto Seiki). The one I had was driven by a small electric circuit rather than a motor. I couldn't find any schematics so I got the oscilloscope out and traced it out.

Of the three I got working again, one had failed capacitors, one had a failed transistor, and one had both the transistor and capacitor failed. I changed these to equivalents and presto. This was six months ago and they are still going...

I think I will look at a way of putting the circuit, waveforms, diagrams (equivalent transistors will have different pin arrangements), and photos into one document and posting it. It should make a nice little article.

Stay tuned.

[Maddos]

That would be great Monkeyman. I've got one apart in our workshop for about a month now. Tried what you did with the replacing electrolytics and tranny (what sort did you use?), but still didn't seem have have enough grunt to maintain oscillations. I started playing around with a 555 timer setup with limited success. Actually got duty cycle so would drive little pendulum well. Kept time well but after stopped and restarted was real hit and miss and would seem to loose sync and fight itself a bit. I was hoping to be able to build a simple and hopefully more reliable driver that you could exchange the little tansistor oscillator circuit with. Given up for now.

[monkeyman]

G'day Maddos,

I like the photo of your zed. Mines the same (except the wheels). I think the metallic blue looks fantastic.

As for the clock, you've noticed the tranny is an 828 (or something that you can't get anymore). I used a BC337. It is just a basic npn BJT we stock at my work. I am sure most common npn BJTs will do the trick. I found that when working, the 828 (or whatever it was) didn't have much grunt and replacing it with the BC337 gave it a bit more. The pin-out is different though! I have started writing up what I did and sketched a pin-out comparison between the two and another common BJT.

You see the little copper-looking metallic disk. It appears to be made up of two windings. From what I gather, one is a 'pick-up'. It detects the magnets on the oscillating disks as they pass. This then creates a pulse, which drives the transistor, which then uses the second coil to give the oscillating disk magnets a little nudge as they pass the coil. Sort of like giving a kid on a swing a push each time they swing past you. I looked at the voltages at the transistor with an oscilloscope and the 828 didn't seem to give much of a push. I don't know if this was a design parameter or if the transistors back then were just junk. The replacement transistor gave it a stronger push and mine has been going strong for over six months now.

Hopefully I will have some sort of write-up in a couple of days to post with pin-outs and waveforms. I will try to make it interesting.