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External 720K floppy drive IBM XT

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    External 720K floppy drive IBM XT

    Hiya all,
    I've got an external IBM floppy drive hooked up to my XT. Seemed to read a disk for a second then fail on reading. Could be dirty heads. I've managed to get one side of the plastic case open but can't seem to get in any further to get to the heads to clean. I've tried a cleaning disk but really want to see the heads and check condition.

    Any ideas how to get in further without breaking the plastic?

    Here are the pics.
    Attached Files
    Not all those who wander are lost. - J. R. R. Tolkien

    #2
    The cleaning disk is sufficient. Opening the drive will only get you more trouble. I don't know what looking at the heads can tell you.
    PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

    Comment


      #3
      Try the cleaning disk first. If that fails, then disassembly is needed. Something big might be jamming the mechanism or it may be necessary to replace the drive.

      The PC Family Service Manual has a diagram of the parts for the 4865 external floppy drive. Ask again if you do decide to conduct the disassembly so one of those with one can verify the correct way. I think I remember a method but I am not sure and don't want to steer you wrong.

      Comment


        #4
        Drvparm needs to be setup correctly and you need to boot from an internal drive

        On my drive I could format and read disks made by the drive itself but not from other machines

        Comment


          #5
          Just to check its not a configuration error. I'm booting MDDOS 6.22 from floppy disk I made. the config.sys has the following command for the driver. For some reason Dos 3.21 does not like the driver.sys.

          DEVICE=A:\DRIVER.SYS /d:2 /f:2

          I've also tried with the /C for the drive door just in case.
          Is this correct?
          Not all those who wander are lost. - J. R. R. Tolkien

          Comment


            #6
            Right, as rmay635703 mentioned Seems to format a disk fine. And can read it but can't read disks formatted on other computers. How strange???

            Are there any work arounds for this? Or is this a limitation. I'm stoked the drive works though
            Not all those who wander are lost. - J. R. R. Tolkien

            Comment


              #7
              Originally posted by robbo007 View Post
              Right, as rmay635703 mentioned Seems to format a disk fine. And can read it but can't read disks formatted on other computers. How strange???
              Are there any work arounds for this? Or is this a limitation.
              Not a limitation according to the announcement letter for the 4865, which is at [here]. The letter includes, "adds the ability to interchange data between IBM Personal Computers with 5.25' diskette drives and those with 3.5' diskette drives."

              Maybe the radial head alignment is out on both drives.

              Comment


                #8
                Originally posted by robbo007 View Post
                Right, as rmay635703 mentioned Seems to format a disk fine. And can read it but can't read disks formatted on other computers. How strange???
                These are the classic symptoms of an alignment issue.

                What about reading a disk made on the external floppy on another computer?
                PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

                Comment


                  #9
                  What Stone said. And--you are using DS2D 3.5" floppies and the DSHD, right?

                  Comment


                    #10
                    Originally posted by Stone View Post
                    These are the classic symptoms of an alignment issue.

                    What about reading a disk made on the external floppy on another computer?
                    I don’t think that’s it, I had a stack of 5 drives all of them had the issue that they could only read disks made by another 4865 on the 5150, could never move data from another 720k system to the pc.

                    It may be a strange bios problem or something else causing this issue but I doubt every 4865 has the exact same alignment issue unless it’s a manufacturing defect

                    Comment


                      #11
                      So, what does AnaDisk say about the suspect floppies?

                      Comment


                        #12
                        Originally posted by rmay635703 View Post
                        I don’t think that’s it, I had a stack of 5 drives all of them had the issue that they could only read disks made by another 4865 on the 5150, could never move data from another 720k system to the pc.
                        IBM clearly states that this drive has that exact capability:

                        Originally posted by modem7 View Post
                        Not a limitation according to the announcement letter for the 4865, which is at [here]. The letter includes, "adds the ability to interchange data between IBM Personal Computers with 5.25' diskette drives and those with 3.5' diskette drives."
                        PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

                        Comment


                          #13
                          The drives in the 4865 are the same as the 5140 so data interchange there should work. But if the drives were all slightly out of alignment when manufactured, how would anyone know? The only drives to test against would be other drives made for IBM.

                          Comment


                            #14
                            Originally posted by krebizfan View Post
                            But if the drives were all slightly out of alignment when manufactured, how would anyone know?
                            I am pretty sure that the manufacturer would have had processes in place to ensure that just-made drives were in alignment. At that time, being a supplier to a big company like IBM could be fatal if 'bad' equipment was supplied to them.

                            Comment


                              #15
                              Originally posted by Stone View Post
                              These are the classic symptoms of an alignment issue.

                              What about reading a disk made on the external floppy on another computer?
                              Disk made on the external floppy does not read on another computer. I get sector errors.
                              Not all those who wander are lost. - J. R. R. Tolkien

                              Comment

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