Pulsar Button Replacement for Dummies?

[abem]

For quite some time, I've been trying to complete a refinishing project on a stainless Pulsar P4 exec that involved removing and replacing the buttons. After at least 3 tries using different techniques (micro butane torch, soldering iron, different tips, solders etc.), I've come to the conclusion that Pulsar button replacement can not be done by mere mortals with any known technology. I've replaced crystals, reed switches etc. and while at times touchy or frustrating, those jobs are always doable with a little patience and persistence whereas this seems a near impossible task.

Problems:
1) Button removal
To get the source buttons to use in the refinished case, I removed them from an existing "scrap" case. Actually, I went through two cases, one very scratched gold filled case, which I used for practice, and one stainless steel case, which I harvested the intended replacement buttons from. In both cases, just removing the buttons proved difficult. To remove the buttons, I used a micro butane torch. It would seem that all you would need to do is to heat up the button covers and then the button assemblies should pop right out, perhaps with a little gentle prodding. Nope. Some buttons pop right out and others remain stubbornly in place. Prodding them during heating convinces them to finally separate, but at the price of warped button covers. For the gold filled case, I needed to heat the case to such a degree that the case was left permanantly discolored and still one of the buttons was hard to remove. So, step 1 is already messy and unpredictable.

2) Button cover damage during removal
Next, we run into problems damaging the button covers in the removal process. Just heating the button covers enough to remove them causes oxidation which leaves the covers blackened and slightly distorted which makes them impervious to solder and not fit correctly any longer. So, even if you can get the buttons and button covers removed, there's no guarantee that they'll be usable afterwards.

3) Magnets separating from buttons
Next, we have the button / magnet assemblies. Rather than the button being solid with a space for the magnet, the buttons are actually hollow and the tiny little magnets are suspended inside of the button on a tiny plate that fits over the base of the button. In my experience, the little plate is rather fragile and after heating tends to detach from the button (it may have originally been epoxied). Gluing the plate back in place over the top of the button is not as easy as it seems and I don't see any other way of affixing it (solder? no way). I managed to break the little plate when peeling it off of the button to reglue it and now I have two tiny little free floating magnets that I'm not sure how to mount back into the buttons. I'll probably need to cut little replacement plates out of metal or something. Any ideas for remounting 1mm by 5mm magnets inside of hollow Pulsar buttons?

4) Mismatched buttons and covers
I took apart two P4 cases and they had completely different button assemblies and slightly different button sizes! One had little cups that covered the button assemblies and the other had little flat plates. The cups are too big to fit in the button holes from cases that use the flat plates. It also appears that various P4 cases had slightly different button sizes. My replacement buttons fit in the P4 case that I was refinishing, but they were a bit small and there was more wiggle than I would have liked. So, there's another potential problem in matching button cover types and button sizes.

4) Resoldering the button plates
This is the big mystery. Once you place the button back in the case, put the magnet plates over the base of the button and place the little curved leaf spring against the base of the button, you need to solder the tiny little button plates over the rest of the button assembly to keep the whole thing together and seal the inside of the case. Most likely, they won't fit perfectly after removing them from the previous case, so you'll probably need to a little sanding, filing or bending to try to get them as close as possible. Next, you need to somehow solder them in place without having them spring out flinging microscopic parts across the room. If you use a soldering iron or micro torch, the solder, having a lot of surface tension, like to bead up on top of the little plate rather than flowing nicely into the tiny gap around the plate. The solder also really doesn't like to stick to stainless steel and so it hides out on top of the button covers, afraid to touch the stainless steel that it's supposed to be adhering to. How on earth do you convince the solder to magically go where you want?!?

5) Button calibration
Just getting the buttons in is one thing - having them function correctly is another. Before you start soldering, you can try to triple quadruple check that the button is placed correctly such that it will activate the reed switch properly. However, once you solder it in place, there's about a 50/50 chance that it won't work and you'll have to desolder it and try again. If the soldering process weren't so darn skittish, this wouldn't be such a problem, but each time you need to touch or heat the button covers, they get a little bit more ruined, so this sort of trial and error becomes problematic.

After careful consideration, I am convinced there is some sort of secret, possibly alien technology at work here. I just don't see how this can possibly be done. I look at the inside of factory finished Pulsar cases and the button covers are so neatly and perfectly affixed - how on Earth is this possible?

After several days of tinkering and case / button mangling, I'm still not even close to getting it right and each time I try, the fragile little button covers get wrecked a little more and the goal recedes farther from sight. Am I missing something? Is there a trick that I'm missing? Do I need to make a sacrificial offering of a Texas Instruments or Fairchild to the LED watch gods or something? What sort of voodoo black magic is required here?

Does anyone have a Pulsar button replacement guide for Dummies or at least some helpful tips? I seem to be getting nowhere with this.

-abe.

[SASM]

Abe,

this is an interesting topic. To be honest I´ve never tried to remove the button but I have three cases with non-working magnet switches. I think about a dirty solution: We could use a touch command module so that there would be no need for button exchangement. At the moment I have Lloyds P4 touch command here. I am not satisfied yet although the display lights up when you push the touch command plate. I am doing research at the moment until this module is perfectly working, so that it might be used for other P4s as well.

Hanno.

[Old Tom]

What did you use for flux when trying to resolder the covers? Was everything spotlessly clean in the jointing area? A BIG electric soldering iron with a shaped tip is the easy way (and by big I mean 150-200 watt iron of the type normally used for stained glass work)- you need a big iron to supply the energy sucked out by the case acting as a heat sink and dropping the temperature.

I seem to remember seeing a picture of this being done in the Pulsar factory and they were using the tiny microflame torches of the type normally used for jewellry work (probably oxy-propane/butane) which put out a LOT of heat and would bring the workpiece up to & hold the temperature very easily- you absolutely have to use a separate flux with these.

The old solder would have been a high Lead content type- if you try to resolder using a modern Lead free solder I have found you get beading whatever you do unless you remove as much old solder as possible.

Magnets hate heat- a lot of heat for a short time is better than a too little heat for a long time (the Golden rule of soldering anything in a watch!).

[charger105]

Hi Abe.
Piotr Samulik has some helpful info on his old website:
http://crazywatches.w.interia.pl/photo/ ... serv2.html

Drop him a line if you like. He's normally very helpful.
Rgds.

[retroleds]

Sorry the button work was going so hard and difficult. I have been doing my taxes and have my family here for "spring break" so didn't have time to chime in.

Removal - they used a fairly low temperature solder. Just throw the case in a 470f.(244c) oven for 5-8 minutes(compared to the glass removal which only needs 350f/175c), grab with a rag, push the button in hard - all comes out with no appreciable distortion. Torchs and soldering rions have a big negative working against them - the shear mass of the case, sucking the heat away from the very transition point that needs to get the hottest. Actually the ONLY point that needs to get hot. Now, you could glue the caps on with some epoxy, after cleaning them up nicely - and think, you will need much lower heat to get it back apart, if necessary. But that is not what you want to do.


Putting it back together. Gotta laugh first , because it is a nice finger burning subject until you come up with a solid plan.

Things I'd suggest:
a) really big soldering iron. Weller SP-80(80 watt) works nicely, but bigger is better. * Grind a flat spot on your tip so you can get maximum contact with the cap. Factory shape doesn't help our cause.
b)Solder wick - to clean thoroughly.
c)solder flux - acid type, I would suggest a paste.
d)low temp. silver solder. Not lead-free stuff with antimony, antimony siezes at various temperatures, making removal and resoldering torturous.
d) Bench vise
e) Various odd Pieces of wood and a bamboo shish-kabob shewer(seriously).

Lay cap on piece of wood, inside up - squish in some fresh solder wick, lay on the soldering iron to lift off old solder - repeat until content with clean..
Throw case in oven to pre-heat, pull out and quickly lock in vise between blocks of wood, cushined with rag/leather/etc. Take a strip of solder wick and go around the opening with the soldering iron and the wick to lift off more solder.
- you'd think the old solder would be nice to solder with. Nah, full of oxidization and impurities. It does not play nice with itself.

Reassembly:
Case in vise - button hole down..
Get button parts into hole, in proper order. Apply solder flux to edges of hole and to edges of cap.
Lay the cap on - press down with the soldering iron. Almost immediately the flux will flow, you will stab a little solder on the joint and it will follow the melting flux.
You will then grab the bamboo skewer(or similar wooden item, not metal) with your free hand, and hold the cap down, while you pull the soldering iron away. Wait 30 seconds, you are done. *Pouring on the beverage of your choice will make the wait shorter.

* The wooden skewer is nice, as it actually grips the cap a little as it scorches from the heat...something metal could just slip around on you.
The skew-ish item might be needed to hold your cap down BEFORE you grab the iron. A third hand would be so useful...

My $0.02 Back to work.

[abem]

Many thanks for the pointers, especially for the detailed, experienced instructions from Ed.

Yes, I think this may help several of my problems. I've been using a very small, finely tipped soldering iron, which makes it impossible to keep the solder hot enough to flow into the desired spaces. I'm seeing exactly what Ed is describing - the solder will flow for just an instant and then stop before getting a go where I need it. A little more flux may help also, although it makes it a little tough to keep things clean. I'll have to look at my solder to see what I've got. Two or three extra hands would help. If I give up, then I'll resort to epoxy, but I really wanted to try to do it the right way.

Dang, this sort of thing just gives you that much more respect for what the Pulsar people managed to achieve. I can't imagine doing this hundreds or thousands of times. Maybe it gets easier after the first few hundred.

-abe.

[retroleds]

Abe:
Seriously, get the big soldering iron. A Weller SP-80 is perfect....cost you less than $20(plus shipping) online. And take a file or grinder to the tip and make a little flat spot on one corner for better surface contact. The tips are copper - apply a little flux to the tip when hot and apply some solder to coat the fresh "wound". That "tinning" will keep the copper from oxidizing and contaminating your work.

Do not get a large iron with temperature control - I actually DO stained glass as a hobby, and those temperature control irons suck. You are moving along slowly and calmly, laying a consistent pattern to your finish. SUDDENLY, it goes cold and you are stuck. A temperature controlled iron IS very nice for fine circuitry work.

If you get a solid gold case you won't have this problem, their caps or plates are usually glued on - be careful when heating them to remove glass - the parts will spring off inside the oven. Lay the watch in a bowl of aluminum foil at very least to catch them. I remember looking frantically for the parts...the solid 14k P4 would never be the same without... Found in the broiler tray

[abem]

Ed,

Yow - tiny 14 KT gold Pulsar parts springing around the broiler! Not recommended! I can only imagine what words were exclaimed. Glad that there was a happy ending.

-abe.

[retroleds]

I can only imagine what words were exclaimed. Glad that there was a happy ending. -abe.

From what I remember, I swore at/around the wife as she decided to "help"(my own fault, was thinking outside my head), which led to a bit of a row. Probably cost me dinner at the very least.