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In the very distant past (late 1980s, early 90s), Olivetti changed their PC keyboard design; it went from having the keyboard PCB assembly inside a metal clamsh
by linker3000 7y ago
In the very distant past (late 1980s, early 90s), Olivetti changed their PC keyboard design; it went from having the keyboard PCB assembly inside a metal clamshell to a bare board with a metallised plastic sheet on the back of the PCB (they 'cheaped out').
We got to know about the design change when a rather large and sprawling local leisure centre reported that often when someone used their walkie talkie near a PC, the screen filled with random characters and sometimes the dot matrix printers would 'go haywire' (CTRL-P = Print what's displayed on the screen).
In effect, the rf signal from the walkie talkies was 'mashing the keys'.
The immediate fix was to swap in some older keyboards, the longer fix was down to Olivetti using better shielding and some appropriately-placed capacitor decoupling on the power and signal lines.
- shifto 7y ago> "In the very distant past (late 1980s, early 90s), Olivetti..." Havnm't heard that brand in a while! I now remember I still have an 486 DX4 100MHz Olivetti laptop. Which is kind of pink-red-brownish.
- heelix 7y agoFirst time I saw a room full of non-crt computer monitors, found out Merrill Lynch moved to a new building to save money. What they discovered is the CRTs would weird out every time the subway train went by. All the cash saved by moving was lost buying the stupid expensive monitors.
- fragmede 7y agoI wouldn't have considered trains to be a source of EM interference but in retrospect it makes sense. one that's amazed me is that military jets and warships cause some of the nearby consumer electronics go wonky, but as they literally run systems that are trying to jam radio waves, it makes a ton of sense that eg garage doors have trouble keeping up.
- tedunangst 7y agoIs it possible the walkie talkie was out of spec as well? Little signal booster added after market?
- martinmunk 7y agoDoesn't have to be. If I TX with 5W near my new Lattitude laptop, the cursor goes all over the place. I've heard of electricians using uhf radios tripping GFI breakers. I guess what is normal power levels in ham / professional radios are much more than most other stuff is designed to withstand.