DS12887 pcb substitute with battery

[Jon Elson]

On 01/22/2017 12:57 PM, allison wrote:
> I don't know about most people but this solution has been around for
> decades.
>
> I locate the battery on the failed part with a small magnet, then grind the
> epoxy down to it then pick it out with a sharp pointed tool.  Once I expose
> the connection point I older two wires then epoxy a small coin-cell holder
> in that spot and it s done.  I've done this more times than I care to count
> and its effective and the replacement battery some over 10 years old
> now have not failed.  But just in case I have a bag of NOS replacements
> (and pulls from socketed boards) all with dead batteries from age.  There
> is no magic to this.
>
>
>
Most of these Dallas clock/RAM chips can be popped open VERY 
easily!  Take an Xacto knife and pick around the edges on 
the pin side, and usually the plastic cover will pop free 
from the epoxy fill.  Then, the cover can be lifted, and you 
will find a standard 28-pin (I think) DIP chip with a button 
cell wired onto the top of the chip.  The ones I've opened 
were not totally filled with epoxy, the IC package acted as 
a sort of dam to prevent the cover from completely filling 
with the stuff.

Jon