Take a look at the Maxim
DS32KHZS 32.768kHz Temperature-Compensated Crystal Oscillator TCXO
Available in 14 pin dip, needs +5 (you have), batt (you have, ground. Supplies
32,768 that you feed into pin 17 of the clock chip after removing the existing
Xtal. Supposed to hold 1 min per year over
Ok, looking at the pictures and the datasheet gives several questions.
1) What signal is on TP1? Is it 32,768 Hz?
2) What does C3 do? Is it used to trim the 32,768 Xtal?
3) Out of curiosity what is the frequency of U2, the oscillator module?
Maybe you can remove the 32,768 Xtal and feed in a
Can you supply any schematics, good images of the electronics? We may be able
to suss out how they do the internal reference.
I am thinking that since it has a 2.4 volt NiCd battery backup that it used
some sort of 32,768 quartz oscillator for time keeping. It may also have some
adjustment
