NVRAM resuscitation (Was Re: SPARCstation 20 with SCSI2SD)

[Alan Perry]

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
>