NVRAM resuscitation (Was Re: SPARCstation 20 with SCSI2SD)

systems_glitch systems.glitch at gmail.com
Tue Nov 27 15:45:55 CST 2018

I'd modified them as Jeff described in the past, but having the repair
boards saves significant time when doing a bunch. It also allows
non-precision cuts, since it doesn't matter if you accidentally destroy the
old connections down to the IC body. It also results in a repaired module
with no battery-on-a-wire, but is still short enough to fit under SBus
cards for the machines that have NVRAM under card slots. Since the repair
boards come panelized in 2x5 grids, I can assemble 10 at a time, which
again, when you're doing a heap of NVRAMs, saves a lot of time.


On Tue, Nov 27, 2018 at 4:05 PM Alan Perry via cctalk <cctalk at classiccmp.org>

> One reason that I buy the new NVRAMs is that I keep failing at modifying
> them. Got the polarity wrong and fried one. I destroyed one cutting down
> to the terminals. I got one working, but have had problems convincing
> the battery to stay in place and not rip the leads off. There is a
> reason I am a software, not a hardware, guy :)
> alan
> On 11/27/18 12:34 PM, Jeffrey S. Worley via cctalk wrote:
> > When I bought that Sparcstation 4/330 at Computer Parts Barn, the 48T02
> > was one of the problems with it.  The chip looks like a piggieback rom
> > encapsulated in epoxy.
> >
> > I was not reinventing the wheel at the time, I think, because it was
> > the year 2000 or so, but I looked for a replacement and found them hard
> > to come by.  So, knowing the battery was most likely the fault, I went
> > about fixing that bit.
> >
> > The battery accounts for the high profile.  You do not have to cut the
> > entire doggone batter off, the terminals are at one side, iirc, the
> > right-hand side if the notch is to your left.  It is high on the epoxy,
> > so all you need do is cut down an eighth of an inch in that region,
> > just shave that top edge until you expose the battery terminals.  I
> > forget how I determined the polarity of them, perhaps I plugged it into
> > the board after and tested the terminals for power, but all you do once
> > you've exposed the terminals is solder a power and a ground wire to
> > them and attach a 3volt battery.  I used a pack with two AA's, in a
> > case so they are user-replaceable.  They are probably STILL keeping
> > time in that machine, wherever DHS took it and my MEGA ST4 and DG
> > MV4000/dc...  That's another story.
> >
> > So refurbishing these chips is a cakewalk, takes 15 minutes (the second
> > time 'round), and will work til' doomsday.
> >
> > Best regards,
> >
> > Jeff
> >

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