Date Command Sensitive Reed Switch

[charger105]

Hello Everybody.
I recently acquired a P3 Date Command that was supposedly not working properly. It was running a continuous seconds count, or sometimes static digits depending on what buttons were pushed.

As it turns out, it works perfectly out of the case. I'm very pleased with this ! it looks like the time button is too strong, or the time reed switch is too sensitive.

Any hints on solving this problem. I read about rotating the reed switch, or moving it further away from the button. Do you pull out all the silicon stuff that supports the reed switch ?

Also, are all the Pulsar magnets the same ? I need to get one, and want to get the original type for this model.

Rgds,
Andrew.

[bruce wegmann]

There is variability in the strength of the button magnets, less so in the sensitivity of the switches. As you have discovered, it means there is limited ability to randomly place modules in cases, and have the watch function correctly. There are a few potential solutions. Least desirable is manipulating the switch itself; you run the risk of breaking it, or just making the problem worse [and, of course, the module loses its' original, unrepaired look]. Next down is attempting to decrease the strength of the button magnet. It can be done with a powerful external field [such as a rare-earth magnet], but the field orientation has to be right, as well as the strength, so again, there is greater potential for making the situation worse. Time Computer technicians at the factory usually dealt with this with the use of what was called a "high-mu shunt". This was a thin piece of special nickel-iron alloy [NOT aluminum or tinfoil!...these have no magnetic properties] about 4x5 mm, with high magnetic-field conductivity, that diverted [shunted] some of the button's field away from the switch, effectively weakening the button magnet. It is placed on the flat plate covering the inside of the button recess. This method is cheap, fast, and poses no risk to any component of the watch. Final option would be to replace the switch, but then you have position and orientation problems to deal with again. I have a few pieces of the shunt material salvaged from dead watches; if you want to try this approach, PM me, and we can go from there. As an aside, it seems unlikely that any watch ever left Time Computer new with one of these in place; they would have had the ability at the factory to make sure everything was working correctly without resorting to what is essentially a repair. These were almost certainly put in when a replacement module was installed "in the field" [installation of these is covered in the Jewelers' Technical Manual, so there is no doubt these were often put in after the watch was originally sold].

[embelton]

place a piece of tinfoil between the module and the button.

[Majestyk]

place a piece of tinfoil between the module and the button.

You beat me to it. :)

[leddwatch]

Embie, your micro-answer made me laugh after Bruces ever so slightly long one!

[embelton]

Embie, your micro-answer made me laugh after Bruces ever so slightly long one!

Leddie:Thats was the point.

[leddwatch]

Man you are on top form lately fella....!

[gjlelec]

Am i missing something (again !!), Bruce says NOT to use tinfoil

[digibloke]

Just because tin has no magnetic properties doesn't mean that it won't work. Electricians tape often works as well. Try picking that up with a magnet (not the sticky side :wink: ).

[retroleds]

I'll weigh in that (a)bruce is right, something magnetic is more likely to provide the proper "shunt" of magnetism needed to correct these problems;(b)electrical tape may help by increasing distance and/or eliminating electrical shorts;(c)"overexposure may kill us, but underexposure causes us to whither away" - it was fine Bruce. Thorough - some good information is alway better, IMO, than sending 10 new guys to their "Death" like kamakazi pilots.. 8) Finding a really thin piece of steel is the problem. .005"/.1mm "gauge stock"is about right.

[charger105]

Thank you for your help with these suggestions, but al-foil or electrical tape didn't help. The reed switch was permanently shorted whenever in the case. I didn't get any of the mu-metal, although Bruce did offer to send some. If anyones interested, I found this mob on the net, and they seem to have quite a selection, and a good explanation of how it works (the Metglass Film look promising):

http://www.lessemf.com/mag-shld.html

Anyway, I got hold of a new reed switch, and replaced the time/command switch. Eventually it woked after rotating the reed switch (so that the edge of the reeds were perpendicular-ish to the magnet). This now works well.
However, the date/command reed switch was also a problem. It was sticking on after pressing the button, when in the case ? Out of the case, it didn't stick on at all ? In fact the module worked perfectly from word go out of the case. I replaced this as well, and the watch now functions correctly in the case. The whold thing was an interesting exercise. Thanks again for your help.

I now need to remove a link from the bracelet (skinny wrists !). Any hints ? I've tried sticking rods into the holes on the side of the link, but it won't budge.

Rgds,
Andrew.

[redled]

I'm going to be doing a reed switch replacement operation myself as soon as my reed switches arrive. I'm curious how you did it without damaging the reeds; they're so delicate. Any hints would be greatly appreciated!

[charger105]

I found them fairly easy to remove. First, I scraped all of the silicon stuff away from behind the switch, with a small craft knife. Then, I desoldered each end of the wires away from the PCB. Then, I whittled down a paddle pop stick into a small screw-driver shape, and pushed the switch out from the other side of the module (there are two access holes). They popped in and out using this method safely and easily.

As Bruce pointed out, it no longer looks original with the bright solder joints, but at least my watch now works !

Rgds.