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  • Author Author: tariq.ahmad
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1980's Cathode Ray Oscilloscope -- The EIectronics Inside 34

 

 

Most people will know an old tube TV, some will know tube oscilloscopes. But how many have seen the insides of a late 80s high quality scope? Will there be any surprises in this broken model?

  • in reply to airbornesurfer

    "... and everything is so visceral that you can almost feel the programs running step by step!..."

     

    I recall that with the old 14" hard drives in the 70's/80's, you _could_ feel the programs running.  image

  • in reply to beacon_dave

    Spacewar! The king grandaddy of all video games! I didn't realize it ran on a PDP-1! I think that's why I love the "retro" tech--there's so much just clever engineering that went into physically wrangling electrons to get them to do what you wanted, and everything is so visceral that you can almost feel the programs running step by step!

  • in reply to a531016

    I think you're referring to Tennis for Two--which was basically Pong, but played on an old radar scope! Vectrex was probably my first exposure to video games. My dentist had one in the waiting room, and I loved playing it! I finally relived a childhood dream when I found one for cheap(ish) on eBay from a seller nearby. It's a great little system, and I plan on posting about it later. Maybe I'll stream some games on Twitch!

  • in reply to a531016

    "...When researching the "pong on a chip" episode I seem to remember that's how pong came about?..."

     

    I recall that the Spacewar! video game on the DEC PDP-1 used a CRT display based on RADAR screen technology. ( 1024x1024 graphics resolution in the late 50's / early 60s. )

     

    Lyle Bickley explains the PDP-1 (and we play the original Spacewar!)

    https://youtu.be/1EWQYAfuMYw?t=725

     

    I also seem to recall that the PDP-1 had oscilloscopes as a display option as well.

     

    Some of the early CAD program development used oscilloscopes in conjunction with light pens and GPIO buttons for user interfacing.

     

    Ivan Sutherland Sketchpad Demo

    https://youtu.be/6orsmFndx_o?t=210

  • in reply to airbornesurfer

    When researching the "pong on a chip" episode I seem to remember that's how pong came about? During a public open day at a research lab, a technician knocked up something to show a basic version of pong to demonstrate what it could do. Or something like that **Citation needed** - if I find a reference, I'll shout!

    I got to play a Vectrex a couple of years pack at the Science Museum, they are soo diffrent to other CRT displays!


  • I've got an oldish (probably 90s-early 00s) scope that came from a medical imaging center sitting on the parts shelf. Thinking of turning it into a mini vector arcade machine (a la Vectrex). At least I'll know more or less what to expect when I open it!

  • in reply to macona

    Like you, I would have assumed it was mu-metal. I'm just reporting here what the service manual says. Perhaps I'm misunderstanding it or it was wrong.

     

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    I think I've read somewhere that once you get up to about 100kHz, mu-metal is no more efficient at magnetic shielding than steel, so perhaps it's down to having a SMPS rather than the mains transformer. We might also indirectly be explaining why they had the mechanical linkage for the mains switch, rather than just running a mains cable to the front. Another possible factor is that this is very much a portable, service instrument, rather than one that would sit on a bench or ride around on a scope trolly, so degradation of the mu-metal from banging it around might have been a potential problem and could have spurred the development of an instrument that didn't need that level of shielding. As you say, though, that still leaves the problem of the steel magnetizing.

  • in reply to a531016

    It would have been better if you tried to repair the scope instead of just tearing it apart. These scopes were very simple and the service manuals are readily available. Just because someone wrote unserviceable on it does not mean it is and with something like the problem it had, no focus control, means that the high voltage and everything else was working, something was probably just wrong in the focus voltage circuit. Probably a very easy fix. Then you can see what's in the scope and have a working scope after. Much more informative than a pile of parts on the table.

  • in reply to jc2048

    Tek is pretty well know for using mu-metal in their scopes. The problem with a steel shield would be that it can retain a magnetic field and mess things up by itself. And generally steel is not a great magnetic shield. Its not like the part was something that was ever going to be replaced.

  • in reply to jc2048

    Amazing - Thank you Jon!

     

    I have to admit, I love an old hand drawn drawing. I was looking at a building layout from 1978 a few weeks back, and it was revision P. I had to feel for the poor draftsman that had to do (likely a minimum) of 20 versions of that!