On May 9, 0:28, Tony Duell wrote:
> > > To upgrade Indigo 4MB SIMMs, you need to find eight 514400 (or
equivalent)
> > > 80ns DRAMs in 26/20-pin SOJ package, and eight SMD decoupling
capacitors
> > > (sorry, don't remember the value but such caps are usually about
> > > 100-200nF). The capacitors are fitted in positions marked C3, C4,
C8, C9,
> > > C12, C13, C17, C18 on the DRAM side, before the DRAMs (which cover
them).
> >
> > Sounds easy enough. Now all I need to do is find someone with an SMD
rework
> > station. ^_^ This'd be a good time to see about upgrading my
SPARCBook2 to
>
> For something like this you could probably use a fine-tipped soldering
> iron and fine silver-loaded solder. You'll have to work slowly and
> carefully, but SMD soldering is possible with normal hand tools...
Indeed it is, and that's what I'd often do, but in this case the DRAMs are
very close together and I don't think it's possible to get even the finest
tip in between, certainly not at the angle needed to get to the pads under
the J-leads.
I used a hot air gun last time -- similar to the type used
for paint stripping or heat-shrink tubing, except that mine is
thermostatically controlled. Use lots of flux, or tiny amounts of fresh
SMD rework solder paste, keep the board level and firmly supported, and
practice on a scrap item first.
Given the lack of space between the ICs, if you do know someone with a
proper SMD rework station, that would be safer. It's worth mentioning that
last time I showed this to someone who does this sort of rework
periodically, the first reaction was a sharp intake of breath!
--
Pete Peter Turnbull
Network Manager
University of York
Received on Thu May 09 2002 - 02:22:00 BST