Repair my Kienzle clock

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Honolulu

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I have the clock out my my not-so-gently hands, and the fusible link, the famous weak spot, has parted company. It will tick and run if I put gentle pressure on the main wheel (surely there's a proper name for it in the business) but when it winds down, without power to the little solenoid, it won't rewind by itself. This clock hasn't worked since I got the car in the mid-80s. I'm on a mission...

The plastic shell of the clock clearly states that repair should only use solder with a melting point of 120 degrees C which equals 248 degrees F.

Has anyone got a pinhead-sized amount of this stuff that could be used to put the fusible link back together? Not surprisingly, I've called 19 different electronics shops and visited one, none of them will either a) do solder work or b) have anything other than "normal" tin-antimony or tin-lead solder. I'm not in the market for ROHS compliance, but that may be moot since I think no lead solder will have a melting point that low.

I have read of good results from North Hollywood Speedo, and there are other otufits that have been used by members of this group. But.... it's only a pin-head sized project. I've arc-welded, mig-welded, heliarced, soldered and brazed with variable results and (I think) would readily get this done if the correct solder were at hand. Looking online the correct stuff may be an indium alloy paste with some flux mixed in. "Indalloy 1" and "Indalloy 18" appear to meet the spec.

SO. Anyone got a teeny bit to share? Beer on me, here, if you happen to...
 
What if you used conventional solder + a low amperage fuse? Doesn't the fusible link basically take the place of a fuse? So solder that sucker up with whatever you have on hand and add an inline fuseholder behind the power lead. What would the normal draw be, a couple of amps? So use a 5A fuse and be done with it.
 
I actually soldered mine 5 years ago on my kitchen table with a dab of plain, standard solder. No issues since, but note that where i live, it doesn't get any hotter then 35 Celsius / 95 Fahrenheit outside. Clock ran fine ever since, at least untill I put my car up in the garage for a light touch up 4 years ago....
Erik.
 
I think those are way too big to be an effective fuse. I've just soldered the link in my clocks with normal solder. Not sure why they felt it was necessary to make it with low temp solder, or indeed, why they tend to fail in the first place. I've seen ones that are dirty, with thickened oil that probably would cause them to wind more often than normal. I suppose that might be enough to trigger the useable link. The other reason they will stop working is the points get dirty and the solenoid won't fire to wind the clock.

That brings up another possible failure mode. If the points arc weld themselves closed, the current will pass through the coil continuously and that will cause it to overheat since it's designed for intermittent operation.
That would indeed be a reason to have a fuseable link inside. You could easily provide a slow blow fuse external to the clock to avoid such a possibility. Normal fuses would not be likely to handle the large impulse the solenoid would pull unless they are excessively large. Slow blow fuses are the answer. Finding the right size would be trial and error, though an oscilloscope would be helpful in showing the size of the current pulse. I may pull out mine when I have the time.... someday.

I'm sure they put the low temp link inside because if the points are stuck, you need to open and clean the clock mechanism anyway and that keeps an unknowing owner from bypassing an external fuse that continues to blow.

I use a synthetic sewing machine oil to lube the clocks after cleaning them with electronics spray cleaner to remove the old oil. That should keep them running well for as long as I'll own them.

Ian
 
mulberryworks said:
That brings up another possible failure mode. If the points arc weld themselves closed, the current will pass through the coil continuously and that will cause it to overheat since it's designed for intermittent operation.
That would indeed be a reason to have a fuseable link inside.
Click to expand...

If the engineers at Kienzle were concerned about overheating due to welded contacts, and if the fuseable link is close enough to the coil (*) that an overheated coil could melt it, then we have an explanation for the use of low temperature solder: it acts as a thermal shut-off, not a current shut-off (which is what a normal fuse does). So thinking of the link as a "fuse" is a bit of a misnomer; it's more of a "thermal overload switch".

An alternative approach to this issue would be to wire a diode across the contacts to absorb some of the inductive kick-back from the coil. That would extend the life of the contacts, reducing the likelihood that they would arc weld themselves closed or develop enough resistance to stop conducting.

*) Admittedly, I've never played with one of these Kienzle clocks, so don't know if a hot coil would cause the link to melt. My 1970 2800 CS probably came with a Kienzle, but it had been swapped for a VDO quartz clock by the time I got it in 1987.
 
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Diodes are more for RF suppression but can help with arcing to some extent. The more conventional approach is a capacitor across the points, sometimes with an added resistor to prevent the stored energy in the capacitor from causing arcing when the points close again.
Distributors use a condenser for the same task, which is just another name for capacitor.

Here's a link that gives some more details. http://www.industrologic.com/mechrela.htm

And here's one with even a bit more information. https://www.allaboutcircuits.com/textbook/digital/chpt-4/switch-contact-design/

So I'd suggest soldering with normal solder and adding a small cap and resistor and reinstalling the clock. Or for that matter, they could be installed external to the clock, across the power supply terminals, since there's nothing else going on inside the body of the clock. Buy a good quality cap so it doesn't fail in 10 years.

Ian
 
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So the gist of it is to use regular solder and put an inline fuse somewhere useful. Given that most fuses are 8 amp, obviously something smaller is appropriate. As many other euro cars used these clocks, I can hope to find the current load mentioned there somewhere, so as to size the aux. fuse. As long as it will be accessible I can start small (say 2 A) with blade fuses and move up.

The thing in question is a "fusible link" so it's (to me anyway) a thermal protection rather than amps matter. But since too many amps running rampant will cause the fuse to blow, perhaps it's moot what it's called.

I went to Youtube for "low temperature soldering" and found that digikey sells just the ticket, as a paste, for about $16. Since there seems to be no one in Honolulu that is remotely familiar with the "real thing" I am left to my own devices, surprise. I'll report when pau, and the dash is back together, and the car runs down for a safety check, so I can drive it. More.

Also, of course, gotta de-solder the electric clock that's only a year newer and look into testing/desoldering/replacing the two capacitors that may be at fault there.
 
I think you've got it, except I'd think that a 2A fuse would not be enough. The total power isn't much, but it comes in a very quick pulse which is why I suggested a slow blow fuse. I'm glad DigiKey has the low temp solder.
Here's a link on slow blow fuses. I don't think they make a blade version.

Ian
 
I fixed mine with regular solder and no additional fuse.
But then again I am know to have a short fuse myself...no extra fuses needed.
 
https://www.sl113.org/forums/index.php?topic=24703.0

Just looking at this myself. Lots of info on the MB, VW and Porsche forums

The above thread has some links to a mod using a capacitor and diode combo to reduce the sparking at the contacts. Not sure if this really eliminates a need for the fuse, but the MB guys seem to assume so

Interesting thought re the heat fuse. The fuse link is right next to the coil so this could be correct

One last thing, the coil already has a resistor wired in parallel to it, so perhaps just adding a cap to this parallel circuit would do it, plus low temp solder to repair the fused link
 
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UPDATE

First, thanks to all who took the time to relate experiences and make suggestions.

This morning I fixed the (I think older) mechanical/electrical clock. First, soldered the fusible link back together with 60/40 solder. Heck with the low temp stuff, live dangerously. Used a 40-watt soldering gun too, with a fine tip. Only needed it for a few seconds. Apply 12V and it "winds" and runs, but seems to run out of gas before the contacts close again. Sputtered some brake cleaner among the various axles, gently blew it dry, and wallah! it runs, and more importantly, after the spring runs down, when repowered it starts up and runs. I think I'll reinstall this one.

The other, "quartz" clock is more problematic. 12V powers a small motor, which is geared down to move the hands. It's visually a simpler device, though there are those capacitors in there. They have different ratings BTW. Anyway, the problem made itself apparent on close examination: there are a pair of gears on a common shaft, that were tilted out of alignment. It seems the end of the shaft, a bit so small that I lost it in the nap of the towel I'd laid on the kitchen table to fix these, was broken off.

Anyone know where I could get this gear? More likely, does anyone have such a non-working clock that they'd like to donate to the cause? Since the motor runs and other gears turn, I'm pretty certain that only the one gear needs replacement. Sending it out is a non-starter, my understanding is the North Hollywod simply replaces the complete mechanism with another. Likely much more cost-effective that way, but not my approach.

In other news, I've been offered an ''89 63CSi in supposedly very nice shape, missing title and no longer in the local County registration database. The current possessor is moving and wants the car to go to "a good home". There is, he says, a way to restore title, involving a court appearance, etc. Might be worth it, but too bad about the AT. Last one I had, an '79 euro, had the close ratio five-speed trans. Great highway car, not so much around town. Gets better gas mileage than the 3.0CS, though.
 
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