John Robertson wrote:

** That should be "Silver Sulphide" = Ag2S


Do you know what "black leg" corrosion is ?

Commonly seen on the leads of small signal transistors made in Japan in the 70s. It often results in the device going noisy or failing completely. Marantz stereo amps were notorious for it.


Can you provide a link to more in depth discussion on your black leg
corrosion? I did a quick search and could only find one reference, and
it merely said watch out for 'black leg corrosion'?


** Not much to be found on the net, but something most service techs have seen.

Bit like the "yellow glue" problem that has plagued countless items and still is.


I have run into a lot of Namco branded ICs from Japan, made in the late
70s that have this problem...


** It's got be due to silver plating the leads.



..... Phil