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Re: [midatlanticretro] WTD: Morrow Wunderbuss Thinker Toys Motherboard Schematic/docs

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  • B. Degnan
    Dan, As always, thank you for your help. Bill
    Message 1 of 12 , May 8 5:21 AM
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      Dan,
      As always, thank you for your help.
      Bill



      >The power supply in that circuit
      >is a -12V not +12V. The voltage regulator part # on there is a 7912
      >which outputs -12V. The part that is blown on there is an electrolytic
      >cap, not a zener (note the + sign on each end of the cap). Both of those
      >parts below the 7912 are the same type of part.
      ><snip>
      > The caps for the 7805 regulator on
      >there beside it are only 2.7uf. I would suggest changing both of them,
      >for sanity's sake--they both might be damaged.
      ><snip>
      >The other important issue is to check the traces for damages when you
      >remove the bad parts. They could have burned through creating an open
      >circuit. So you'll have to splice the traces back together if this is
      >the case. Some skinny telephone copper wire always does the trick. And
      >last but not least, is the 7912 voltage regulator. You should check the
      >-12V power before you plug in any cards.
    • Herb Johnson
      Bill Degan posted here a request for zener diode information for a Morrow Wunderbus card; he said I did not have that manual listed. Bill also sent me a
      Message 2 of 12 , May 8 10:29 AM
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        Bill Degan posted here a request for zener diode information for a
        Morrow Wunderbus card; he said I did not have that manual listed. Bill
        also sent me a request privately.

        In fact, I DO have that manual listed on my site, and I replied to
        Bill with some zener information. Meanwhile Dan replied here at MARCH:

        Dan <ragooman@...> wrote:
        >
        > I almost posted a lengthly explanation on the march group list before I
        > noticed you posted the pic on cctech. The power supply in that circuit
        > is a -12V not +12V. The voltage regulator part # on there is a 7912
        > which outputs -12V. The part that is blown on there is an electrolytic
        > cap, not a zener (note the + sign on each end of the cap). Both of
        those
        > parts below the 7912 are the same type of part.

        ..among other comments.

        This is why I don't do diagnosis of S-100 problems by email. There IS
        a zener diode on the Wunderbus, and I conveyed to Bill the information
        about it, and offered a manual to him. As for the picture, I've not
        seen it, so I have no idea what the actual problem is. I don't follow
        cctech simply because I can't keep up with traffic. I can't really
        keep up with it here "in" MARCH for that matter.

        For those who don't know: I have a very very large collection of S-100
        manuals, from which I offer good photocopies for a modest fee per
        page. Yes, there are free PDF's on the Web: my customers tell me that
        my copies are superior, and I have manuals not otherwise available.
        The fees I charge allow me to continue this service, year after year.

        http://www.retrotechnology.com/herbs_stuff/s100.html

        Oh, and the title at that home page advises "I let the MANUALS do the
        talking". Most S-100 manuals provide schematics, circuit and
        programming descriptions at length: some include source code listings.

        Herb Johnson

        Herbert R. Johnson, New Jersey USA
        <a href="http://www.retrotechnology.com/herbs_stuff/"> web site</a>
        <a href="http://www.retrotechnology.net/herbs_stuff/"> domain mirror</a>
        my email address: hjohnson AAT retrotechnology DOTT com
        if no reply, try in a few days: herbjohnson ATT comcast DOTT net
        "Herb's Stuff": old Mac, SGI, 8-inch floppy drives
        S-100 IMSAI Altair computers, docs, by "Dr. S-100"
      • B Degnan
        Here is a pic of the effected area on the board: http://www.vintagecomputer.net/Morrow/wuderbuss_mb_s-100.jpg Bill
        Message 3 of 12 , May 8 10:36 AM
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          Here is a pic of the effected area on the board:

          http://www.vintagecomputer.net/Morrow/wuderbuss_mb_s-100.jpg

          Bill
        • Herb Johnson
          ... Shorted tantalum capacitors. They do that with age, short out and then try to conduct a few amps until they flame on. Literally. Schematic says....1 uFd
          Message 4 of 12 , May 8 11:42 AM
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            "B Degnan" <billdeg@...> wrote:
            >
            > Here is a pic of the effected area on the board:
            >
            > http://www.vintagecomputer.net/Morrow/wuderbuss_mb_s-100.jpg
            >
            > Bill

            Shorted tantalum capacitors. They do that with age, short out and then
            try to conduct a few amps until they flame on. Literally.

            Schematic says....1 uFd (one microfarad). Probably should be 25 volts
            or higher. Mind the polarity when you install them! note the "+" markings.

            Herb
          • B Degnan
            Herb, Thanks. I am learning more every day, thanks to you and others who reply to my questions so kindly. Bill ... -END-
            Message 5 of 12 , May 8 11:53 AM
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              Herb,
              Thanks. I am learning more every day, thanks to you and others who reply
              to my questions so kindly.
              Bill

              > "B Degnan" <billdeg@...> wrote:
              >>
              >> Here is a pic of the effected area on the board:
              >>
              >> http://www.vintagecomputer.net/Morrow/wuderbuss_mb_s-100.jpg
              >>
              >> Bill
              >
              > Shorted tantalum capacitors. They do that with age, short out and then
              > try to conduct a few amps until they flame on. Literally.
              >
              > Schematic says....1 uFd (one microfarad). Probably should be 25 volts
              > or higher. Mind the polarity when you install them! note the "+" markings.
              >
              > Herb
              >
              >
              >
              >
              > Yahoo! Groups Links
              >
              >
              >
              >


              -END-
            • Bob Grieb
              Nice photo. Made me want to get some marshmallows... Do you have fire insurance? ... __________________________________________________ Do You Yahoo!? Tired
              Message 6 of 12 , May 8 3:32 PM
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                Nice photo. Made me want to get some marshmallows...
                Do you have fire insurance?

                --- B Degnan <billdeg@...> wrote:

                > Here is a pic of the affected area on the board:
                >
                > http://www.vintagecomputer.net/Morrow/wuderbuss_mb_s-100.jpg
                >
                > Bill
                >
                >


                __________________________________________________
                Do You Yahoo!?
                Tired of spam? Yahoo! Mail has the best spam protection around
                http://mail.yahoo.com
              • Dan
                Herb, I like all of the back stories on your website regarding the history of designing all the vintage microcomputers. That s something I always like to
                Message 7 of 12 , May 8 5:45 PM
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                  Herb,

                  I like all of the back stories on your website regarding the history of
                  designing all the vintage microcomputers. That's something I always like
                  to collect too, beginning with the minicomputer company where I used to
                  work, SEL. There's a good book, if you haven't seen it, it's called the
                  Engines of the Mind, where it has many of the back stories from the
                  early machines up to the microprocessors.

                  =Dan

                  [ My Corner of Cyberspace http://ragooman.home.comcast.net/ ]



                  Herb Johnson wrote:
                  >
                  >
                  >
                  > For those who don't know: I have a very very large collection of S-100
                  > manuals,
                  >
                  >
                • Dan
                  At my old job(Lucent), I had to troubleshoot across the pond using a vnc server on a HP16500 analyzer (unix) and a Motorola processor emulator from Amsterdam
                  Message 8 of 12 , May 8 6:10 PM
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                    At my old job(Lucent), I had to troubleshoot across the 'pond' using a
                    vnc server on a HP16500 analyzer (unix) and a Motorola processor
                    emulator from Amsterdam to Chicago.
                    Always alot better than email but it helps with someone at the other end
                    to wakeup and turn on the equipment (the 6hr time zone didnt help
                    either--Shanghai was even worse).

                    =Dan

                    [ My Corner of Cyberspace http://ragooman.home.comcast.net/ ]



                    Herb Johnson wrote:
                    >
                    >
                    >
                    > This is why I don't do diagnosis of S-100 problems by email.
                    >
                    >
                  • B. Degnan
                    ... LOL
                    Message 9 of 12 , May 8 6:48 PM
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                      At 03:32 PM 5/8/2007 -0700, you wrote:
                      >Nice photo. Made me want to get some marshmallows...
                      >Do you have fire insurance?
                      >
                      >--- B Degnan <billdeg@...> wrote:
                      >
                      > > Here is a pic of the affected area on the board:
                      > >
                      > > http://www.vintagecomputer.net/Morrow/wuderbuss_mb_s-100.jpg
                      > >
                      > > Bill
                      > >


                      LOL
                    • jack99rubin
                      ... with a ... Anyone ... for this ... I can ... Being on the digest version of the list, I m a little slow to get messages and being disorganized enough that
                      Message 10 of 12 , May 9 7:29 PM
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                        :
                        >
                        > Herb/Anyone else..
                        >
                        > I have a 1977 Morrow Wunderbuss "Thinker Toys" S-100 Motherboard
                        with a
                        > blown Zener diode near a 12+V position at the back of the board.
                        Anyone
                        > have a schematic? I checked Herb Johnson's site, there is nothing
                        for this
                        > board listed. I would like to determine the exact type of diode so
                        I can
                        > replace it.
                        >
                        > What would cause a Zener diode to pop?
                        >
                        > Thanks.
                        > Bill
                        >

                        Being on the digest version of the list, I'm a little slow to get
                        messages and being disorganized enough that it took a couple of days
                        to find my Wunderbuss manual, I'm a bit slow to respond...I think
                        Herb pretty much covered all the relevant points.

                        All I can add at this point is that the tantalum caps associated with
                        the voltage regulators on this board are listed as 1 ufd on the
                        schematic and called out as 20v parts in the parts list.

                        Certainly no reason not to go with a higher voltage replacement -
                        these guys tend to provide a common source of entertainment on many
                        S100 systems and also frequently self-destruct on Heathkit H89
                        systems. Yet another good reason to avoid leaning over a vintage
                        system when you first power it up after a long rest.

                        Always glad to pay my respects to Chairman Morrow,
                        Jack
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