New to the forum but not to the Vintage HP world + HP-01

[Geoff Quickfall]

Pm sent

HP used a 38.4 kHz crystal cut to vibrate at that frequency. They then timed it to 30 seconds a year. It is temperature sensitive though. Also, as it ages it will drift. Prior to failure, and some do fail, they drift rather a lot.

HP included a trimming capacitor which can fine tune the watch frequency. The trimming capacitor is also temperature sensitive. Do not attempt to change the trimming capacitor factory setting. These age and become brittle.

You say 2 minutes drift, over what period of time? What are you using as a base reference for time?

The watch looks spectacular.

Now if the 2 minutes (a day) is annoying enough then securing a 38.4 kHz crystal for replacement becomes problematic, unless someone out there has a source other then dead modules. If too annoying then I suggest a PANAMATIK module and harvesting the LED display as a donor. Keep the old module as it is functional.