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smellsofbikes
smellsofbikes • diaspora
I have what was a fairly high-end oscilloscope in the 1980's, and one of the probes failed. I ended up cutting it apart to figure out why. This is a 350MHz probe, not a cheap piece of equipment. It has a coax cable that goes into a connector, where the connector attaches to the scope itself, and the cable is held to the connector with a crimp, so I cut through that.
The enter pin that goes into the scope, on the other end where it meets the cable, is just a sharp spike. It was pushed into the center of the cable to be in contact, but not actually attached solidly to, the center conductor of the coax cable. The conductor had oxidized and that's why the cable was conducting poorly or not at all. This seems like a lousy way to make a probe that cost the equivalent of about $300USD. Grumble.
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Clara Listensprechen
Clara Listensprechen friendica
Turns out that late 80s early 90s was an era when studies in connectivity resulted in touting wire-wrap as a be-all-end-all improvement over soldering. after all, solder does have its own connectivity problems especially in extremely warm/hot environments and proper soldering methodology. There was also the bruhaha over the hole in the ozone layer blamed on commercial chemicals beyond just freon for compressors--but also the chemicals used to clean flux off of printed circuit boards that were dip-soldered...upshot of which tight mechanical connections were in vogue at the time, at the commercial production level.

At 350 Mhz, solder on a BNC pin would have been a serious monkeywrench in the works besides. Since you mentioned "high end" and the frequency of the probe, BNC connectors are presumed.
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Clara Listensprechen
Clara Listensprechen friendica
Tektronics 'scope, perchance?
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tom grzyb
tom grzyb • diaspora
"made in China"
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Karl Auerbach
Karl Auerbach • diaspora
I wonder if I still have my old wirewrap tools (for when we'd need to install or remove the"NPR" jumper on a DEC Unibus backplane.)
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David Bump
David Bump • diaspora
They may not have expected a 40 year service life?
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smellsofbikes
smellsofbikes • diaspora
I think service life is part of it but test equipment is notorious for being always on for 20 years.
I wish they'd spotwelded it the way they do with thermocouple ends.
It's a LeCroy scope. I prefer them as they're generally much easier to repair than Tektronix. This one has a backplane with the front end amps on it, and the CPU, the channel processors, and the video card are all plugin boards I can swap out from a spare or buy individually on eBay.
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Karl Auerbach
Karl Auerbach • diaspora
Sounds a lot more modern than my father's ancient scopes - those used car battery jumper cables as probes. The other end of the probes were attached to a volunteer who was positioned at a blackboard so that the electrical pain level could be plotted vs time, thus creating the oscilloscope.
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Clara Listensprechen
Clara Listensprechen friendica
In antiquity, 350 Mhz was technically impossible to achieve when you go back far enough into the history of oscilloscopes, so that would also mean that spot welding outside of the automotive manufacturing and construction businesses wasn't heard of either. Not sure if electronics spot-welding was even contemplated in the 1980s.
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smellsofbikes
smellsofbikes • diaspora
If I repair this, I'll do what I do with thermocouples: set the power supply at 4V and 17A and lightly tap the wire/pin junction briefly. Zap!
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Clara Listensprechen
Clara Listensprechen friendica
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