Being an analog engineer, I’m around “more experienced” engineers on a daily basis. However, a group of younger engineers often find ourselves acting much older than we are, shouting things like “Get off my lawn!” and “Back in my day…” (really, we had a whole list).
Anyway, another common one that comes up is “They don’t make ’em like they used to!”. Do we as engineers know WHY they don’t make them that way anymore? Of course we do. The lower reliability and requirements for many more people to assemble the devices honestly doesn’t make sense these days. With lower priced labor the world over and low tolerance for waste and inefficient processes, I know I wouldn’t make the proverbial “them” that way anymore. It just doesn’t make sense.
But why am I mentioning this? In episode 12 of The Amp Hour, Dave Jones and I were discussing the Tektronix scope that I currently have disassembled and am attempting to piece back together in working order. It’s the 485M, the military version of the very popular scope. Right now I’m looking at getting the power supply back on its feet, the voltages were woefully low. More on that in later posts hopefully. For now, let’s concentrate on looking at the awesome design tactics and fabrications inside an old scope.
Note: I am a pretty bad photographer, please excuse any non-professional looking images.
A view of the quite complex button schema of old Tek scopes. Each button controls an individual switch, pot or selector switch. And yet it has many of the features of modern scopes match these exactly.
I LOVE modular design and this is a great example. If a technician (a Tek Tech?) found that a module wasn’t performing correctly this entire module could be switched out to check to see if it is indeed this module.
A closer view of the module. Of note is the resistor jumpered directly across the signal lines of the end connector. Perhaps this is a later fix for a customer issue. It’s also a good view of a mechanical connector that reaches all the way back from the front of the module. It’s a compound switch, pulling on it activates the arm in one direction and pushing on it does some other completely different action.
A close up view of the modular connector. I also like seeing the layout patterns done by hand before CAD programs were prevalent. Interesting to see where they flooded the ground planes.
A closer view of the analog components on one of the modules. Notice this was mainly resistors and a smattering of socketed op amps.
Another view of a mechanical arm reaching all the way to the back of the chassis. Likely a custom part as discussed on The Amp Hour.
This selector switch was the main voltage range switching. It had a compound action as well (inside was a fine tuning I believe) whereas the outside switch was the larger 1-2-5 multiple decade switching.
And finally, a view from the top. Note the >7 kV warning on the CRT tube. No touch!
So there it is, as Dave calls it, “nerd porn”. Isn’t it interesting to see how instruments were constructed not too long ago? It sure was more labor intensive and likely much more expensive than you can pick one up today on ebay. The benefit is that the hand-made and through-hole nature of this board makes it ripe for fixing AND without straining my fragile old eyes. Dangnabbit!