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MPI 360k won't read/write

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    #31
    I'm pretty certain that the drive uses the same head suspension that the 5x series uses--the casting is the same and the connectors appear to be the same.

    So, here's the MPI 51 drive manual.

    My guess is that at some point, someone tried to clean the heads a bit too aggressively and deformed the suspension. It should be possible to bring it back to operation.

    Comment


      #32
      Yes there is a tail there:

      20190812_130144.jpg

      20190812_130154.jpg

      So is there a way to readjust things without messing up the alignment?

      Comment


        #33
        No, there's nothing on the leftmost 2 pins of the large red connector in your 2nd photo. You definitely don't have a HL solenoid.

        Your photo betrays the problem you're having. Both photos show that the spring sheet metal head support has been distorted on the right side (looking toward the back of the drive), which means that the head isn't making good contact on that side.

        If you remove the head and sheet metal spring and try to straighten in, you'll very likely mess up the alignment, as you suspect. It might be possible to get the thing working halfway by bending the coil spring lead (using 2 pairs of long-nosed pliers to exert slightly more force on the head. This isn't great for disks, but it might work in a pinch.

        So, it seems to me that you've got two options--fix the sheet metal spring and struggle with realigning or do a half-a**ed fix that might be good enough for now.

        If Dwight has any better ideas, I'm open to suggestions.

        Comment


          #34
          Originally posted by Chuck(G) View Post
          No, there's nothing on the leftmost 2 pins of the large red connector in your 2nd photo. You definitely don't have a HL solenoid.

          Your photo betrays the problem you're having. Both photos show that the spring sheet metal head support has been distorted on the right side (looking toward the back of the drive), which means that the head isn't making good contact on that side.

          If you remove the head and sheet metal spring and try to straighten in, you'll very likely mess up the alignment, as you suspect. It might be possible to get the thing working halfway by bending the coil spring lead (using 2 pairs of long-nosed pliers to exert slightly more force on the head. This isn't great for disks, but it might work in a pinch.

          So, it seems to me that you've got two options--fix the sheet metal spring and struggle with realigning or do a half-a**ed fix that might be good enough for now.

          If Dwight has any better ideas, I'm open to suggestions.
          I was thinking of maybe affixing a small weight of some kind to the head armature. Or something like plasticine on the head 'tent'. Just enough to get it there?

          I don't know how good the alignment is. When I got this drive, it did not work (probably was always bent like that). This was many, probably 15 years ago when I knew a lot less than I do now. I'm sure I made things worse by playing with the resistor trimmers above and goodness knows what else. I'm shocked the thing actually can read anything at all. So we might be clinging to an alignment that isn't any good.. unless by some fluke it is actually aligned properly with the head weighted down.

          Comment


            #35
            Well, if you fancy that you can handle alignment issues, the best repair is to remove the head assembly and straighten that spring. Be sure to mark reference lines on the parts, however, so you stand a chance of getting things right again.

            Doubtless the head azimuth will be off, but as long as it's close, you'll be okay.

            Comment


              #36
              While we're on the subject of MPI 5x drives, if you look at the PCB on the front left side of this photo:



              You'll see a row of holes for a 10-position header. Ever wonder what it's for? It takes a small plug-on PCB with a 9602 dual monostable, some capacitors, a trimmer and a couple of resistors. It generates a READY/ signal based on the index interval.

              MPI PCBs varied quite a bit. My 5x for 100 tpi has a huge stepper, about 2" in diameter.

              Comment


                #37
                The best way to make a mark is to use a small triangular file and make a notch towards the back on either side. It would cut into the square washer, spring and base. Having them on both sides would help getting it right.
                I was right that the spring hinge looked a little wanky.
                Dwight

                Comment


                  #38
                  I'd just grab my diamond-tipped scribe and make my marks. A carbide scribe would work just as well. No need to notch anything.

                  Comment


                    #39
                    Let me follow up by saying that if you work with metal at all, one of these is an inexpensive addition to your toolkit. Your local big-box or hardware store usually has them--they can scribe glass as well.

                    If you're of the inclination to drill holes in metal, an automatic center punch is an essential tool that will give you an accurate starting "dimple" for your drill. I also use one to set wirewrap pins.

                    Comment


                      #40
                      I've got one of those. The advantage of the file is that you can insert the file to get best alignment. From past experience, scribing across three surfaces, with one being a thin spring is a little on the tough side.
                      Dwight

                      Comment


                        #41
                        Do whatever works for you. I'm not overly optimistic on the success of a repair in any case.

                        Comment


                          #42
                          Originally posted by Chuck(G) View Post
                          Do whatever works for you. I'm not overly optimistic on the success of a repair in any case.
                          The same here. Repair is given about a 30% working. Using a weight is not likely to work well either. With the spring tweaked like it is, the head will have a different force on the leading than the trailing edge. This is likely to cause premature wear on the disk.
                          Work straightening the spring, one bend at a time. This will reduce the chances of breaking it.
                          It would be better to find another complete head assembly. The only issue there is you'd likely have to adjust for both disk track 0 and the track 0 sensor.
                          Dwight

                          Comment


                            #43
                            Yeah, someone familiar with watchmaking or a jeweler could probably figure this out. My impulse might be to take a couple of small pieces of brass bar or rod stock and cut a slit in the side near the end of each with a jeweler's frame saw. You could then slip both over the spring and see if you could correct the bend by manipulating both. You could also try a jeweler's angled burnisher, with a block under the spring and see if that might straighten things out.

                            It's just that once the head's removed from its suspension, things get pretty nasty.

                            Comment


                              #44
                              So I took a chance and removed the head, bent the copper leaf spring just enough to get the top head to sit down properly.

                              The drive reads directories fine. I can create directories and small batch files. The working drive can read both. But I cannot read or copy larger files, either from the working drive or entirely on the non working one.

                              I played around a little with one of the trimmers I know I had messed with and got it to a point where I could write batch files pretty much as large as I wanted.. but still no 'regular' file copying. I get either sector read or sector write failure, or general failure.

                              Comment


                                #45
                                Try a little more weight to see if it is still contact issues.
                                Also check the rotation speed.
                                Dwight

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