[time-nuts] I love the smell of tantalum in the morning

Bruce Griffiths bruce.griffiths at xtra.co.nz
Sat Nov 5 15:29:13 EDT 2016


On Saturday, November 05, 2016 12:12:18 PM Tom Van Baak wrote:
> See C13 in the attached photo. I need to replace some blown caps on a 
few
> boards [1]. In one instance the cap got so hot it melted itself off the
> board. Quiet convenient, actually -- it acts like its own fuse -- but I
> don't think the 5071 designers had that clever feature in mind.
> 
> Having not done SMT before, how should I do it with minimal risk to the 
very
> precious PCB. Or, what equipment should I use this as a good excuse to 
buy?
> 
> Thanks,
> /tvb
> 
> [0] http://www.imdb.com/title/tt0078788/quotes
> [1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
Tom

Either a hot air jet as used for smt desoldering will work.
A variety of nozzle shapes and sizes are available.

or

One can use a fine tip iron to alloy the solder with a low melting point 
solder alloy making it very easy to remove the component and then 
cleanup the pads using fluxed copper braid or even a cotton bud. Its 
essential to remove the low melting point alloy before resoldering.
 
CHIPQUIK SMD N1 works well with both leaded and unleaded soldered SMT 
parts
Bob Pease touted RF induction heated irons. Hakko makes a nice one 
(FX100) now the patent has expired.

Bruce


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