Loading ...
Sorry, an error occurred while loading the content.

RE: [midatlanticretro] Re: FD 1771 - Floppy Drive Controller TAX?

Expand Messages
  • Bill Sudbrink
    Ok, here are a couple of weird things that have bit me in the past: Cracked pins. I have had TI pins crack in such a way that they looked good in place,
    Message 1 of 29 , Apr 4, 2012
    • 0 Attachment
      Ok, here are a couple of weird things that have "bit" me
      in the past:

      Cracked pins. I have had TI pins crack in such a way that
      they looked good in place, would test good with a probe but
      were bad during a run. I've seen two kinds of cracks.
      Warning, bad ASCII art follows:


      | | <-1
      | |
      \ /
      \ /
      || <-2
      ||
      \/

      I have seen cracks at position 1, right where the pin makes
      the bend to go into the chip body. Straight across the bend
      on a soldered chip. Almost invisible to the naked eye.
      Pressure from a probe on top of the pin closed the crack and
      made the pin look good under test.

      I have seen cracks at position 2, at the bottom of the taper
      where the pin narrows to its insertion width. I have seen this
      in both soldered and socketed chips. In the socketed case, I
      stupidly didn't notice the missing piece of pin through several
      removal/insertions. Under test, it can behave just as above,
      with the pressure on the pin closing the circuit.

      On other thing I have seen exactly once was a case where the
      pin from the socket was crumpled under the socket. This board
      was probably machine assembled. The crumpled pin was making
      intermittent contact with the solder pad that it had been
      intended to be soldered to. It was one of those tall, solid
      body sockets making the problem very difficult to see.

      Bill S.
    • Evan Koblentz
      ... That might be the post of the year.
      Message 2 of 29 , Apr 4, 2012
      • 0 Attachment
        >> I've seen two kinds of cracks. Warning, bad ASCII art follows

        That might be the post of the year.
      • joshbensadon
        Hi Bill, Thanks, that s good solid advice. I found a #2 break on one of the front panel chips. Always good to check the pins of the sockets too. I ll give
        Message 3 of 29 , Apr 4, 2012
        • 0 Attachment
          Hi Bill,

          Thanks, that's good solid advice. I found a #2 break on one of the front panel chips. Always good to check the pins of the sockets too. I'll give the board a good visual before moving the problem to a bread board (what would be my next step without your input).

          I am also curious about the -5V. I saw some chips don't require it. But I think I have chips that do.

          While fixing an Ohio Scientific Superboard, the extra pressure I applied to the pin when scoping it had it make contact to the socket. I caught on to this pretty quickly but it still tricked me at first.

          Again, my biggest stumbling block on my 1771 problem is how it produces valid numbers when there are 2 data pulses for every clock pulse. This leads me to believe the CPU decoding/interfacing is correct, along with my code. I don't believe the data sheet and circuit could be wrong either. So there's something here that I've never seen before... but with a little patience and persistence I might have a good story to tell!

          Cheers,
          Josh


          --- In midatlanticretro@yahoogroups.com, "Bill Sudbrink" <wh.sudbrink@...> wrote:
          >
          > Ok, here are a couple of weird things that have "bit" me
          > in the past:
          >
          > Cracked pins. I have had TI pins crack in such a way that
          > they looked good in place, would test good with a probe but
          > were bad during a run. I've seen two kinds of cracks.
          > Warning, bad ASCII art follows:
          >
          >
          > | | <-1
          > | |
          > \ /
          > \ /
          > || <-2
          > ||
          > \/
          >
          > I have seen cracks at position 1, right where the pin makes
          > the bend to go into the chip body. Straight across the bend
          > on a soldered chip. Almost invisible to the naked eye.
          > Pressure from a probe on top of the pin closed the crack and
          > made the pin look good under test.
          >
          > I have seen cracks at position 2, at the bottom of the taper
          > where the pin narrows to its insertion width. I have seen this
          > in both soldered and socketed chips. In the socketed case, I
          > stupidly didn't notice the missing piece of pin through several
          > removal/insertions. Under test, it can behave just as above,
          > with the pressure on the pin closing the circuit.
          >
          > On other thing I have seen exactly once was a case where the
          > pin from the socket was crumpled under the socket. This board
          > was probably machine assembled. The crumpled pin was making
          > intermittent contact with the solder pad that it had been
          > intended to be soldered to. It was one of those tall, solid
          > body sockets making the problem very difficult to see.
          >
          > Bill S.
          >
        • joshbensadon
          Yeah! Thanks for the Bad Ascii art warning! lol.
          Message 4 of 29 , Apr 4, 2012
          • 0 Attachment
            Yeah! Thanks for the Bad Ascii art warning! lol.



            --- In midatlanticretro@yahoogroups.com, "Evan Koblentz" <evan@...> wrote:
            >
            > >> I've seen two kinds of cracks. Warning, bad ASCII art follows
            >
            > That might be the post of the year.
            >
          • Bill Sudbrink
            ... Actually, that s old usenet code for be sure your viewer is set to a fixed width font or this won t make any sense . Bill S.
            Message 5 of 29 , Apr 4, 2012
            • 0 Attachment
              Joshbensadon wrote:
              >
              > Yeah! Thanks for the Bad Ascii art warning! lol.
              >

              Actually, that's old usenet code for "be sure your viewer is
              set to a fixed width font or this won't make any sense".

              Bill S.
            • joshbensadon
              ... I never joined usenet. How long ago was usenet popular? Is it still around? I recall the days of BBS s and all the cool ANSI art. There wasn t a need to
              Message 6 of 29 , Apr 4, 2012
              • 0 Attachment
                > Actually, that's old usenet code for "be sure your viewer is
                > set to a fixed width font or this won't make any sense".
                >
                > Bill S.
                >

                I never joined usenet. How long ago was usenet popular? Is it still around? I recall the days of BBS's and all the cool ANSI art. There wasn't a need to worry about fixed width then, it was all 80 column.
              • Dave McGuire
                ... It s still around, and it s still active. I was shocked out of my gourd to find this out about a year ago. I thought it was completely dead. I was (among
                Message 7 of 29 , Apr 4, 2012
                • 0 Attachment
                  On 04/04/2012 07:22 PM, joshbensadon wrote:
                  > I never joined usenet. How long ago was usenet popular? Is it still
                  > around?

                  It's still around, and it's still active. I was shocked out of my
                  gourd to find this out about a year ago. I thought it was completely dead.

                  I was (among other things) a news admin at a large ISP for a long
                  time. We bought one of the first SGI Origin 2000 systems to build a
                  news server; that was fun.

                  When I learned that it was still active, I built a news server here
                  and finagled my way into getting a news feed. I get all the major
                  hierarchies but no binaries. (I don't care about the binaries) The
                  technical groups, in particular, are wonderful. My news server receives
                  between 30,000 and 40,000 articles per day. (remember, that's not
                  including binaries!) Probably 1/3 of that is spam, but the rest is a
                  lot of good meat.

                  -Dave

                  --
                  Dave McGuire, AK4HZ
                  New Kensington, PA
                • Dave McGuire
                  ... I ve seen this failure mode as well. In one case, microscopic examination revealed that the only thing holding the pin together was the thin layer of
                  Message 8 of 29 , Apr 4, 2012
                  • 0 Attachment
                    On 04/04/2012 10:12 AM, Bill Sudbrink wrote:
                    > Ok, here are a couple of weird things that have "bit" me
                    > in the past:
                    >
                    > Cracked pins. I have had TI pins crack in such a way that
                    > they looked good in place, would test good with a probe but
                    > were bad during a run. I've seen two kinds of cracks.
                    > Warning, bad ASCII art follows:
                    >
                    >
                    > | | <-1
                    > | |
                    > \ /
                    > \ /
                    > || <-2
                    > ||
                    > \/
                    >
                    > I have seen cracks at position 1, right where the pin makes
                    > the bend to go into the chip body. Straight across the bend
                    > on a soldered chip. Almost invisible to the naked eye.
                    > Pressure from a probe on top of the pin closed the crack and
                    > made the pin look good under test.
                    >
                    > I have seen cracks at position 2, at the bottom of the taper
                    > where the pin narrows to its insertion width. I have seen this
                    > in both soldered and socketed chips. In the socketed case, I
                    > stupidly didn't notice the missing piece of pin through several
                    > removal/insertions. Under test, it can behave just as above,
                    > with the pressure on the pin closing the circuit.

                    I've seen this failure mode as well. In one case, microscopic
                    examination revealed that the only thing holding the pin together was
                    the thin layer of oxide. That was a serious pain to track down.

                    -Dave


                    --
                    Dave McGuire, AK4HZ
                    New Kensington, PA
                  • joshbensadon
                    I ve been struggling with this Tarbell 1011 controller using the FD 1771 controller for a couple of weeks. I kept getting FF s out while I was watching good
                    Message 9 of 29 , Apr 6, 2012
                    • 0 Attachment
                      I've been struggling with this Tarbell 1011 controller using the FD 1771 controller for a couple of weeks.

                      I kept getting FF's out while I was watching good data go in.
                      The only time I got any other data, was when the (external) Clock/Data seperator swapped the clock & data.

                      I looked everywhere for the problem. I even made my own Clock/Data test pattern generator to give clean pulses. Once again, only when I reverse Clock and Data does it seem to work.

                      So, I swaped the Clock and Data. Curiously, the circuit now works!

                      The first ID field looks like this...
                      FE 00 00 01 00 D2 C3

                      I am assuming the CRC (D2C3) is correct.

                      Does anyone have any ERRATA on the FD 1771 Floppy Drive controller?

                      I am curious if anyone else out there has any schematics or circuits using the FD 1771 with external data seperator and would you confirm Pin 27 for Data, Pin 26 for Clock (as per data sheet) or are these truely reversed?

                      PS. Thank you to everyone for all the help, support and invaluable idea's given. And sorry for the mess of hair on the floor :)
                    • B Degnan
                      Herb Johnson would know a lot about that stuff, but he is not usually checking this list. He can be contacted through his web site retrotechnology.com
                      Message 10 of 29 , Apr 6, 2012
                      • 0 Attachment
                        Herb Johnson would know a lot about that stuff, but he is not usually
                        checking this list. He can be contacted through his web site
                        retrotechnology.com
                        http://www.retrotechnology.com/herbs_stuff/s100bus.html
                        Bill

                        At 10:47 AM 4/6/2012, you wrote:
                        >I've been struggling with this Tarbell 1011 controller using the FD
                        >1771 controller for a couple of weeks.
                        >
                        >I kept getting FF's out while I was watching good data go in.
                        >The only time I got any other data, was when the (external)
                        >Clock/Data seperator swapped the clock & data.
                        >
                        >I looked everywhere for the problem. I even made my own Clock/Data
                        >test pattern generator to give clean pulses. Once again, only when
                        >I reverse Clock and Data does it seem to work.
                        >
                        >So, I swaped the Clock and Data. Curiously, the circuit now works!
                        >
                        >The first ID field looks like this...
                        >FE 00 00 01 00 D2 C3
                        >
                        >I am assuming the CRC (D2C3) is correct.
                        >
                        >Does anyone have any ERRATA on the FD 1771 Floppy Drive controller?
                        >
                        >I am curious if anyone else out there has any schematics or circuits
                        >using the FD 1771 with external data seperator and would you confirm
                        >Pin 27 for Data, Pin 26 for Clock (as per data sheet) or are these
                        >truely reversed?
                        >
                        >PS. Thank you to everyone for all the help, support and invaluable
                        >idea's given. And sorry for the mess of hair on the floor :)
                        >
                        >
                        >
                        >
                        >
                        >------------------------------------
                        >
                        >Yahoo! Groups Links
                        >
                        >
                        >
                      Your message has been successfully submitted and would be delivered to recipients shortly.