27 Nov
2018
27 Nov
'18
1:45 p.m.
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.
Thanks,
Jonathan
On Tue, Nov 27, 2018 at 4:05 PM Alan Perry via cctalk <cctalk at classiccmp.org>
wrote:
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