13 Jun 2006, 01:06
I'm not a tech, so take what I'm saying carefully.
I've had troubles with two autoset P4s, they both presented the same flaw: They started to go into autoset mode by themselves as soon as batteries were inserted. I don't know if any of you guys has encountered this same problem, but I guess is not that infrequent with these modules.
Here's my solution.
The IC terminals that control time and date functions are powered through the reed switches. Positive (+) is fed through the reeds to the terminal. This is its normal operation, but when they go bad, time & date IC terminals become very (and I mean VERY) sensible, even the slightest contact with anything conductive (of course with the reed switch disconnected) makes the IC light the display. It is easy to understand what causes the "self-autoset" - the IC feels the terminals are always energized. The only way to keep the watch running unlit is to disconnect the reeds at their IC contact point. It seems that the IC has lost some internal resistors or condensers or whatever. Only way is to reproduce them on the external part of the circuit...
I've made some trials, and come up with this technique: By inserting a 1.2 M-ohm resistor between the reed switch and the IC terminal, the operation of the module becomes normal again. Space is not a problem, because autoset P4s have blank setting reed switches spaces in the sleeve, and a 1/8W resistor fits snugly in that place. Yes, I know 1/8W res. are not widely available, but places like Digi-Key or Farnell have plenty and they're very cheap.
This is the first part...
When I inserted the module back in the case, put on the batteries and the caseback on, it started to go nuts again. This time it didn't go into autoset mode, but for some bizarre reason, the time button activated date, and the date button did nothing. I lost a lot of time trying to understand what was the basic difference between the "in-case" status and "out-of-the-case" status. I thought it could have something to do with button cells' weaker energy (I used an AA power supply outside) but it was nothing of all this. I found the solution by chance. I discovered that if powered by power supply, the module in the case worked. I went on, and inserted the batteries (357) but not the caseback. It worked! So? It had to do with the connection bar grounded to the caseback? Exactly. Once removed from the caseback and reglued back on isolated, it worked flawlessly. I can only guess that the whole case worked as a sort of a magnetic cage, but of course is just a guess.
Anyway, both modules work perfectly now - and the cost of the operation is just a few cents, if you don't mind some spare "after-dinner" time...
I hope this will be useful to someone experiencing this same P4 weirdness.
Al. :D
I've had troubles with two autoset P4s, they both presented the same flaw: They started to go into autoset mode by themselves as soon as batteries were inserted. I don't know if any of you guys has encountered this same problem, but I guess is not that infrequent with these modules.
Here's my solution.
The IC terminals that control time and date functions are powered through the reed switches. Positive (+) is fed through the reeds to the terminal. This is its normal operation, but when they go bad, time & date IC terminals become very (and I mean VERY) sensible, even the slightest contact with anything conductive (of course with the reed switch disconnected) makes the IC light the display. It is easy to understand what causes the "self-autoset" - the IC feels the terminals are always energized. The only way to keep the watch running unlit is to disconnect the reeds at their IC contact point. It seems that the IC has lost some internal resistors or condensers or whatever. Only way is to reproduce them on the external part of the circuit...
I've made some trials, and come up with this technique: By inserting a 1.2 M-ohm resistor between the reed switch and the IC terminal, the operation of the module becomes normal again. Space is not a problem, because autoset P4s have blank setting reed switches spaces in the sleeve, and a 1/8W resistor fits snugly in that place. Yes, I know 1/8W res. are not widely available, but places like Digi-Key or Farnell have plenty and they're very cheap.
This is the first part...
When I inserted the module back in the case, put on the batteries and the caseback on, it started to go nuts again. This time it didn't go into autoset mode, but for some bizarre reason, the time button activated date, and the date button did nothing. I lost a lot of time trying to understand what was the basic difference between the "in-case" status and "out-of-the-case" status. I thought it could have something to do with button cells' weaker energy (I used an AA power supply outside) but it was nothing of all this. I found the solution by chance. I discovered that if powered by power supply, the module in the case worked. I went on, and inserted the batteries (357) but not the caseback. It worked! So? It had to do with the connection bar grounded to the caseback? Exactly. Once removed from the caseback and reglued back on isolated, it worked flawlessly. I can only guess that the whole case worked as a sort of a magnetic cage, but of course is just a guess.
Anyway, both modules work perfectly now - and the cost of the operation is just a few cents, if you don't mind some spare "after-dinner" time...
I hope this will be useful to someone experiencing this same P4 weirdness.
Al. :D
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