Some pics of all this, 1mm graph paper background

The sides of the cap unfurled, A-A is the distinct cutoff line of the rusted
part, the roughness at the ends is my butchery, also clean originally
http://home.graffiti.net/diverse:gra...t/1N5812_a.jpg

The green glass filled seal around the anode pin
http://home.graffiti.net/diverse:gra...t/1N5812_b.jpg

Its unaffected partner, as far as not being ohmic anyway
http://home.graffiti.net/diverse:gra...t/1N5812_c.jpg

View of the gold metalisation over the base metal stub, Os are below some of
the largest areas of erosion. I don't know where the missing gold went to ,
no flakes or obvious dust lying around in the diode when first broken into.
The weld for the anode pin is off-centre as can be seen in the pic, is that
relevant ?
http://home.graffiti.net/diverse:gra...t/1N5812_d.jpg

Edgewise view of the die , showing gold metalisation up to the die but much
is eroded away , eg base metal showing between C-C and the most obvious
accretion bridging the edge of the die marked with the Vs
http://home.graffiti.net/diverse:gra...t/1N5812_e.jpg

looking down on the large gold metalised areas with Bs showing the most
obvious bits of base metal, the bright line is the die edge
http://home.graffiti.net/diverse:gra...t/1N5812_f.jpg
the wavy gold edge ,near it, is probably metalisation over some underlying
pad so presumably at manufacture rather than a later formation

These diodes were stored anode upwards in kit , untouched for 13 years, so
something made the dust aggregate and migrate vertically , against gravity

it is now reading 13 ohms


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