[time-nuts] Timebase Replacement - Seiko Epson RTC-72421

[Corey Sukalich]

Hi all,

New to the list, but have known of its existence for a while as I know others that have been subscribers.

My question pertains to a timebase used in a Schulmerich carillon bell tower system from the 1990’s.

The Seiko Epson RTC-72421 Real Time Clock Module (4-bit) is used, but the clock ends up walking to a noticeable degree (minutes) over a period of months.  Is this expected for the device in question, or could it possibly have a defect?

Datasheet available here:
https://support.epson.biz/td/api/doc_check.php?dl=brief_RTC-72421&lang=en <https://support.epson.biz/td/api/doc_check.php?dl=brief_RTC-72421&lang=en>  

From what I can tell it uses an internal oscillator, so it sounds like I would need to find a drop-in replacement or build a module that will replace it with a significantly better time standard.  Any advice is appreciated as to whether could be accomplished without too much trouble.  I’ve repaired a few of these systems over time and there are enough of them still in the wild that it might be worth me fabricating a module for them.

Also, on the off chance someone is versed in EPROM data recovery or knows of a resource for it, I would appreciate that information as well.

Regards,
Corey
N9WIV