My thirteen dollar 7000-1 Transoceanic stopped working last night. I traced the problem to one of the transistors in the IF strip, then substituted with the ubiquitous 2N2222A and the set came right up.

When I examined the transistor I took out I noticed some bright places around the leads. Examination under magnification revealed lots of tiny bright spots all over the insulator between the leads and the case. Cleaning these deposits off brought the transistor back to life and made the radio happy.

This phenonenom is the transistor version of the infamous silver mica disease and was found back during the space program. Apparently it was not yet fixed when the transistors for this TO were made. Now I can wait for the next infection.

RRM

Interesting & thanks for posting... What did you use to remove the conductive "spots" ?

John

The tip of an exacto knife blade.

RRM

That's very interesting! Hadn't seen that one before.

Brett

Sounds like the "tin whiskers" problem.

...now, this makes me wonder if the transistors in the (a few years later) D7000 series were also subject to this phenomenon...something to watch out for, for sure...