My 8656B ...
I pulled bits. I checked the schematic. I did tests. Everything said it should work, so I put it back together.
I now have output.
... and the attenuation looks like it is functioning normally.
Not sure how I feel right now....
I had a similar problem with a relay cabinet back in the day when I was working automation... one of the air solenoids for a welding jig was intermittent. The line foreman replaced the solenoid itself, verified it had voltage when it should, so when it continued to malfunction they called me. I checked for the usual; cleaned out the cabinet with compressed air, looked for binding pivot points, went over every crimped connection between it and the cabinet, even removed and inspected the associated relay, which looked like brand new, even the contacts were shiny silver and you could see the pattern where the contacts wiped with self-cleaning action.
Put it back in & ran the test routine 50 cycles and the jig performed flawlessly. Line foreman decided it was working, let it run til it dropped again. I stood there and watched that relay work for over 30 minutes... it performed flawlessly. Then I happened to notice a little shiny dot on the top of the relay directly under the suspect one in the next row down. At first I thought it was just a bit of overspray or a sticker; but I put my finger on it and it came away stuck to it. Turned out to be a little disc of clear blister-pack plastic like one might expect if one punched a hole through a carded part with a paper punch. I might never have noticed that thing, the lighting was just right.
I can't prove it, but I believe that disc had somehow gotten lodged in the relay, and when I handled it, the little gawddammitt fell out.
I had the same problem with my 3478A. Cleaned the F/R switch a dozen times, no joy. Took it apart and cleaned it bit by bit manually, found NOTHING. Put it back together and it worked perfectly, and continues to do so to this day. I would still be baffled by this turn of events, except for the fact that
while going back through my pics of the work, I found this.
The point being... while it is true that
"Murphy's a bitch, and she has puppies.", if you DO get lucky and make something work without knowing how or why... sometimes the best course is to just use the damned thing and see if it continues to work.
"When Ifni smiles upon you, smile back and say 'Thank you'."About 80% of
Helldesk Service DEPENDS on this principle.
mnem
"Sufficient unto the day is the evil thereof."