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EEVblog #1334 – Mystery Dumpster Teardown

Mystery dumpster teardown time! With the most amazing mechanical mains power switch you’ll ever see! ...


  1. Fantastic stuff!

    I have a couple of these myself as I love the retro gear!

  2. Yeah, it’s pretty much the ultimate retro geek porn. I’ve enjoyed it very much, thanks!

  3. I thought the Epsom HX-20 from about 1982 was the first laptop/notebook?

  4. That potting compound goes brown with heat and temperature. Once its brown it becomes conductive, was the killer of many VCRs in the past(was fixable however).


  5. Retro computing , I love it . But maybe is time to do some electronics ? upgrade this stuff ??

  6. I remember lusting after one of those, but I never could afford one. Notice two things about the keyboard: One – no wimpy membrane, but an individual switch for each key, individually soldered to the board. Two, a sensible layout, with the caps lock key tucked away where you don’t hit it accidentally, while the ctrl key is right near the home row, where it’s easy to reach. Brilliant!

  7. It’s amazing how much work was put into designing these things, hats off to all those people who worked on it, without them nothing we take for granted today would be possible !

  8. I read about potting compound used by some Japanese company that over time actually turned corrosive.

    On same note, has the battery been replaced? My Amiga and PC batteries had leaked but I was able to clean them up in time so they still work.

  9. Take more stuff like this apart, it’s interesting. The odd retro review might be fun if you reviewed it in the context of the year it was manufactured.

    You’ve been lucky that the device wasn’t sealed with a warranty sticker, or had a screw hidden under the sticker in the middle.

  10. Really neat, one of my favourite teardown so far, they just liked nice and tidy work back then. Thank you so much Dave !

  11. Interesting about the caps. Friend at work brought me a power supply for his big screen LCD. He wanted to know if it was salvageable.

    I looked at the caps. Leaking, bulging and Chinese, the lot of them.

    Told him to order some decent quality caps and replace them. He reported back a couple weeks later that the unit was now back in service once he replaced the cheap ass caps.

  12. Thoroughly enjoyed this teardown. As someone else suggested a hack on something retro after the teardown would make for a very interesting vid.

  13. You mention the circuit board layout yet didn’t mention it was laid out by hand with different with tape on a clear sheet to make the photo screen which is how boards were done back then.
    You can see the proof in the traces that aren’t completely straight but instead curve in all sorts of unique shapes.

  14. In case you missed it, this made me giggle:
    @5:31 “It’s a DB25 because they didn’t use DB9 in those days”
    @6:04 “DB9 barcode interface”

    (Dave, thanks for the *awesome* show; I hesitate to post smart-ass comments, but that was just too good to pass up! 🙂

    BTW, I found an inflation-conversion calculator and $1400 in 1983 is equivalent to $2976 in 2009 dollars.

  15. I love how the keyboard feels on the TRS80 Model 100, the weird squishiness of the keys was very satisfying to type on.

  16. Little nitpick: It’s DB-25, but DE-9. There’s no such connector as DB-9, though that mistake is common enough that you’re almost always safe to assume “DE-9” any time you hear or read “DB-9”. The ‘E’ or ‘B’ letter refers to the size of the shell, while the number refers to the number of pins.


    And of course, as Dave points out, DE-9 wasn’t widely used for RS-232 until the IBM PC-AT started using it, in 1984. Before that, serial was almost always done with DB-25.

  17. I remember a friend of mine had one of these at school (they had become quite a bit cheaper by then). I was SO envious! Maybe I should take my Sinclair Z88 apart to compare the two!

    Coincidentally, I saw this site earlier, it has loads of scanned promo material from the early 80s, and this one shows the 100 on Page 8. http://www.atarimagazines.com/whizkids/showpage.php?issue=computertrap&page=8

  18. I wanted one of these for BBSing SO bad back in the day.

    Absolutely beautiful job Dave.
    This was the kind of episode that makes me want to shake your hand and buy you the beverage of your choosing.

    What I find funny is that I work for a company that re-manufactures industrial gear and I see boards of that construction quite often.

    -and you pegged it. It’s usually (but not always) a couple of worn out electrolytic capacitors that get replaced and that stuff is out the door for another decade.

    Really great blog, Dave!

  19. This takes me back a bit!
    I was working for Tandy prior to this being released and I had one locked in my drawer for weeks getting familiar with it prior to release. I had to support it and tell all the store managers about it.
    I also remember having the source code for the ROM – as a printout!


  20. “Don’t turn it on, take it apart! Mwahahahahaha!”


    Very enjoyable teardown, nonetheless. Interesting to see those few surface mount components starting to come in.

  21. Nyargh. Let’s try again, this time without my text being mangled by the blog software:

  22. There ARE SMD ceramics on the LCD controller board 😉

  23. Nice blogpost Dave, I hope you do more PCB analysis in some upcomming blogs. It was a long time ago since you did analysis like this.

    Would love to see more blogs where you simply show a board like this and talk some about it. Why caps are placed where they are, why a certain lines are drawed a certain way to ovoid loops, emission etc.

    Regards, Robert

  24. I’m pretty sure this board was laidout by hand using ruby lith film and chart pak tapes. The traces are curved because that’s what you do when you use 1/8″ wide tape. The layout would probably scaled up 2X or 4x. The ground planes and power traces were cut out from the ruby lith film. The layout is not angular as they would have looked from being done with a photoplotting cad system. A photoplotter and all the required software would have cost $500,000 or so. The first company that I worked for in the late ’70s used a Calcomp system for some of the pcb board work. The bulk of the smaller boards were done by hand on ruby lith film on a huge 4′ x 8′ light table.

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