Andy Cuffe wrote in message
...
On Mon, 27 Apr 2009 23:52:05 +0100, "Dave Plowman (News)"
wrote:

I've got a B&D stapler which has died. The solenoid is ok, so it's
likely
a fault on the PCB. Which is potted in what looks like epoxy resin on the
component side.

I'd normally just buy a new one - but have trillions of staples for it
bought off Ebay.;-)

I can get a new PCB for approx 60 gbp - but that's more than the thing
cost new.

Any ideas about removing the potting compound hopefully without damaging
the identification on the components? I've likely got everything on that
board 'in stock' so would be happy to replace the lot. But don't have a
schematic.


Use a heat gun set to a temperature below the melting point of solder.
Epoxy gets much softer and weaker as it heats up. At the right
temperature, it will scrape off like putty.
Andy Cuffe




But the solder is still connected to active components and now surrounded in
a large thermal mass, not the quick jab and scarper of the soldering
operation

For a populated board , how high a temp would you allow the epoxy and hence
thermal mass of enclosed active componentry to get up to?
I think I would bury a diode in there and monitor the forward voltage for
temp guide.
I'de be happy with 70 degree C and probably 100 deg C , but how much higher
?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/