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Re: Reforming Capacitors: EAI Analog Computer TR-48

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  • joshbensadon
    ... Thanks David, Your capacitors are those larger can types. Almost like Coke cans? Computer Grade capacitors. The caps in this computer look more like
    Message 1 of 31 , Oct 11, 2012
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      --- In midatlanticretro@yahoogroups.com, David Gesswein <djg@...> wrote:
      >
      > On Thu, Oct 11, 2012 at 03:28:37PM -0000, joshbensadon wrote:
      > > Does anyone have any experience or remarks to make about these CAN
      > > capacitors from the late 50's or early 60's?
      > >
      > Mine were mid 60's. Are these aluminum electroltytics or one of the older
      > technologies? You will find people have widely varying options on what
      > to do with them. What I did:
      >
      > http://www.pdp8online.com/straight8/ps_restore.shtml
      >

      Thanks David, Your capacitors are those larger can types. Almost like Coke cans? "Computer Grade" capacitors. The caps in this computer look more like those found in the old Tube TV's. They are chasis mount with tabs and would typically have 2 or 3 capacitors inside. I always thought it was clever to code the terminals with shapes, triangle, square, circle. Something I've not seen very often however, is these caps have a carton sleeve over them? I guess it's to electrically insullate them. I don't think it's very good for the caps thermal disipation.

      I read on one site that I should be reforming them for several hours. Some suggested up to 40 hours. I think I'll go for the 40 hours but at 25% rated voltage for the first 24 hours.

      Bottom line, your caps definitely exhibited the need for reforming and these caps are just as old or perhaps a few years older. That's valuable information right there.

      Cheers,
      Josh
    • Bill Dromgoole
      ... Yes, In my opinion you are correct. In the early years of semiconductors most parts have three digit date codes. You have to know the approximate decade
      Message 31 of 31 , Oct 18, 2012
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        >
        > Here's a transistor with 430 on it. Would that make it 1964, week 30?
        > Transistor part number is 2N1218. Or does the 430 refer to the factory the
        > transistor was made? or other?
        >
        > Photo of transistor posted in the photos/Josh Bensadon folder of this group.
        >
        > I've seen some IC's with only a 3 digit code on them (not part of this analog
        > computer). Case in point is the following:
        >
        > CD4023BE
        > RCA H 650
        >
        > Is that to mean 1976 week 50?
        > H being the factory where it was made?
        >
        > Cheers,
        > Josh
        > ------------------------------------

        Yes, In my opinion you are correct.
        In the early years of semiconductors most parts have three digit date codes.
        You have to know the approximate decade the part was first produced to get the
        correct date.

        Sometimes you have trouble telling the part number apart from the date code.
        In the 1970s a lot of the 7400 series ic's had date codes like 7414 and a part
        number like 7404.
        I was always having trouble with those.

        A good history of early transitor marking can be found here.
        http://transistorhistory.50webs.com/index.html

        billdrom
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