I have a few ksu’s sitting on the floor in my basement. A while back I went to move one and found it stuck to the floor. The cover of the 551b was open with the green goo all over the card cage and out the bottom cable opening. I first thought that something had leaked onto the KSU through the ceiling. Then I examined the power supply to see if the electrolytic capacitor had leaked. Checking the line card( 400D issue 14), it seemed that the goo was coming out from under the 327A reed relay( 3rd quarter,1972,Kearny). I pried the relay off the line card and found that the potting compound had completely liquified and leaked out of the relay. This is really strange since none of the other dozens of line cards I have has done this.
This is where the old Bell System is sorely missed. Bell Laboratories would have launched an investigation into the mystery of the liquefying potting compound and found the answer.
I don’t know if you guys have ever seen copies of the old “ Bell System Technical Journal”. Most of the articles are incomprehensible except to engineers and physicists, but every so often there was an article that a layman could halfway understand. An article in 1953 detailed the unexpected failure of relay contacts. An unknown organic compound was growing on palladium contacts. This organic compound eventually insulated the contacts causing failures. After going through explanations about palladium contacts, #1 and #2 Bell System contact metal and much scientific testing, it was determined that the source of organic compound was a chemical being outgassed from the relay spoolhead insulators. The solution found was to goldflash all contacts on wirespring relays and all palladium contacts. The organic compound was found not grow on gold. After all the testing and research the article ended on page 40 with” the exact mechanism of how the organic compound grows on palladium contacts is not understood at this time”.