[rescue] Sun Ultra 2 series PROMs

Carl R. Friend crfriend at rcn.com
Thu Jan 2 21:46:33 CST 2014

    On Thu, 2 Jan 2014, Jonathan Katz wrote:

> A while back I was whinging that I had an Ultra 2 with a dead PROM battery.
> And I have the same problem with my E3000.
> [...]
> I then took a look. The ICs for the Ultra 2 and for the E3000 IO board are
> the same. ST M48T59Y-PC1s. Although NOS of these chips exist, I doubt they
> still have good battery cells on them. Thanks to Google, we can find the
> pinouts.

    There's more to these "chips" than meets the eye.  For instance,
don't bother trying to hot-wire full-time power to them as that's
pointless.  The key is to get at the circuitry that is driven by the
lithium battery that's in the "upper compartment" of the device and
tap into that device with an external -- and replaceable -- battery.
Too, make sure that the original is disconnected; else the thing
will only be a parasite and draw down your replacement.

    The more I think about the matter, the more I see the creeping
influence of "enforced obsolescence" (nevermind "planned") on the
hardware so equipped.  We can consider it as a predecessor of the
non-replaceable battery in the iPod.

    Finding the embedded lithium battery can usually be done with a
moderately-powerful magnet.  Getting at the thing is down to skill
with hand-tools or a Dremel (When one has a Dremel, *everything* is
compatible!) to expose it and gain access to the two ends.  After
that, it's a simple matter of severing the connections to the old
battery and soldering wires to connect to a new cell-holder.

> Am I reading the diagram correctly, or after I hook all this stuff up, will
> I have some pretty blue smoke? We'll see :D

    You probably won't have "pretty blue smoke", but if you don't isolate
either pin 28 or 14 your poor battery will (1) try to power the entire
system when the thing is otherwise powered off and (2) will try to gain
a charge when the system is powered on -- which, for non-rechargeable
batteries is usually a bad idea.

    I really don't mean to sound like a "crusty old fart" in this
regard, but there are *very* good FAQs on this very topic because
given "enforced obsolescence" (especially as new parts are no longer
manufactured) a lot of us have hit the issue head on.  I have more
than a few systems that need such work.  I'm pretty handy with hand
tools, but am seriously considering getting a Dremel with a good
cutting head capable of abrading phenolic.


| Carl Richard Friend (UNIX Sysadmin)            | West Boylston       |
| Minicomputer Collector / Enthusiast            | Massachusetts, USA  |
| mailto:crfriend at rcn.com                        +---------------------+
| http://users.rcn.com/crfriend/museum           | ICBM: 42:22N 71:47W |

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