A few years ago I bought a few Dallas DS1216E clock modules. Like this:
They are direct replacements for the original SMT "No Slot Clock". It goes underneath the CD ROM in the IIe or the CF ROM in the Platinum IIe, and under the system ROM in a IIc.
They contain an embedded 3 volt cell of which all are long dead. There is a hack to attach an external battery like a CR2032. I further modded the chip by grinding out the potting epoxy around the embedded coin cell and physically disconnecting it by grinding away its leads, and then re-potting it in epoxy to prevent any leakage.
All well and good - I installed them in several of my systems and they've worked for years.
Recently the one in my daily use IIe failed. The driver wouldn't recognize the clock's presence in the system. I got one of my spares. Same thing.
I tried the installed ones in my other machines - all of them failed.
So I bought four more.
One of them failed right off the bat. No recognition.
The funny thing is, the driver recognized the presence of the chip, but by the time bootup was complete and the No-Slot-Clock utilities ran, they couldn't find the clock. Rebooting, the driver failed to recongnize the clock. All the remaining three did the same thing.
Now why do you suppose that all of these DS1216E modules failed all at once? And across multiple systems.
I'm loath to buy a new production No-slot-clock from Reactive Micro at US$40 plus another $30 shiping to Canada, it'll cost me $100 (canadian) or more just to get it here and if it too fails...
Anyone have any ideas?