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Thread: Push On/Push Off Switch Repair in a HP 700/43 Terminal

  1. #1
    Join Date
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    Default Push On/Push Off Switch Repair in a HP 700/43 Terminal

    full writeup: http://www.glitchwrks.com/2018/07/31/hp-700-43

    I picked up a HP 700/43 terminal in a larger lot of equipment recently. It seemed to work, but the power switch would pop out as soon as pressure was removed. This seems to be a pretty common thing. I took it apart to remove the switch and find a replacement, but discovered there's no direct replacement available, so I took it apart and came up with a quick fix. There's a little plastic plate that's supposed to have a plastic pin about 0.040 inch in diameter, which rides in a series of channels in the switch's actuator. This pin is what causes the switch to latch in the on position. It was totally broken off flush with the plate. I discovered that a large paper clip is about 0.040 inch in diameter





    Didn't even require glue, it was a press fit in a #60 drilled hole. Put it back in the switch body with a dab of Lucas Red 'n Tacky grease:



    Now 100% functional! I cut the pin long and filed it to 0.077 inch. Filing to the right length and then deburring also means it's less likely to chew up the channel in the plastic switch actuator. Apparently the same Preh switch is used in a lot of Commodore monitors, so perhaps this is a convenient quick fix for Commodore owners, too!

  2. #2
    Join Date
    Jan 2007
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    Nice work! Push on/off "latching" switches, some with builtin LEDs are very common cheap fare on eBay also.

  3. #3

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    Nice one A couple of months ago i replaced the power switch on my Philips CM8833 after using it with the switch jammed in with a matchstick for some months, I found a new switch on ebah, not an exact match for the original, I had to snip off 3 pins but it fitted and works fine, Seem's to be a common problem with those type of switch's

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