DS12887 pcb substitute with battery
elson at pico-systems.com
Mon Jan 23 11:04:16 CST 2017
On 01/23/2017 04:57 AM, allison wrote:
> On 01/22/2017 02:46 PM, Chuck Guzis wrote:
>> On 01/22/2017 10:57 AM, allison wrote:
>>> I don't know about most people but this solution has been around for
>>> 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.
>> It's worth noting that the original post was about fabricating a
>> replacement using the DS12885A RTC chip. However, most old PCs used the
>> DS1285 RTC (inside of a DS1287 module). The DS12885A is supposed to be
>> drop-in compatible with the DS1285, but apparently, in some cases is not.
>> So there's logic in reworking the old DS1287 modules, as the DS1285 chip
>> is long out of production--you'll most likely have to be content with
>> pulls or the occasional NOS lot.
> I haven't seen that version for a while. The later are fully versions
> are epoxy filled.
> Same for the MT48T part, same fix.
> The problem with NOS parts is manufacture date. Some are really old.
Well, it doesn't really matter. If you can find one of the
"really old" ones, the battery can be replaced and you are
good for 5 years or so. There must be TONS of these old
clock/RAM chips out there, and somebody must have saved a few.
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