Macintosh Plus 800K circuit

Discussion in 'Apple Collectors' started by mikemike690, Feb 9, 2016.

  1. mikemike690 macrumors regular

    mikemike690

    Joined:
    Apr 7, 2012
    Location:
    New Zealand
    #1
    I opened the floppy drive to clean and I noticed that the little circuit board on the photo below was snapped? Is there anyway to either replace or fix? Thanks.
    http://imgur.com/rrrbgZv
     
  2. MacTech68, Feb 10, 2016
    Last edited: Feb 10, 2016

    MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #2
    If the wires are long enough to reach the circuit board, remove the wires from the broken rear portion and solder them to the corresponding pins on the optical sensor.

    DO NOT remove or loosen the screw that holds the optical sensor. It's factory aligned for track zero.

    Thus:

    800K Floppy Trk0 PCB.jpg
     
  3. mikemike690 thread starter macrumors regular

    mikemike690

    Joined:
    Apr 7, 2012
    Location:
    New Zealand
    #3
    Okay thanks, I've done that but don't think the connections are that good, anyway before I saw your message I plugged it in for about 10 seconds at the max and the drive was now clunking/rattling and running without a disk, what would cause that? Thanks.
     
  4. MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #4
    If you've accidentally shorted any of the pins on the sensor, the drive will keep trying to move the head ro the track zero position, never stopping. Alternatively, the eject mechanism is stuck, trying to eject.
     
  5. mikemike690 thread starter macrumors regular

    mikemike690

    Joined:
    Apr 7, 2012
    Location:
    New Zealand
    #5
    Thanks, I'll try to fix it tomorrow morning and post an update if not in a couple days
     
  6. mikemike690 thread starter macrumors regular

    mikemike690

    Joined:
    Apr 7, 2012
    Location:
    New Zealand
    #6
    Okay so I've fixed the wiring, booted the computer, and it's not clunking, but as soon as I insert a disk it rejects it and has a X floppy disk icon. Any ideas?
     
  7. MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #7
    Dirty heads, wrong system, corrupted disk, wrong format, bad alignment.

    If you're going to clean the heads, DO NOT pull the top head up higher than normal as you will stretch the pressure spring and the head assembly will be permanently damaged.

    The heads are the raised block of highly polished ceramic with a black stripe across the middle. You can use a q-tip/cotton bud to clean them, but be careful not to snag the cotton in the copper plate they sit on. The copper base has slots cut in it to allow the head to self align on the disk media. If it catches and you pull, you can bend the copper and make the head sit at a bad angle.
     
  8. mikemike690 thread starter macrumors regular

    mikemike690

    Joined:
    Apr 7, 2012
    Location:
    New Zealand
    #8
    Thanks, it will be alignment because I actually dropped the drive, (don't ask how). How do you align it? Thanks
     
  9. MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #9
    That's not an easy thing to do. Usually it requires proper test equipment, an alignment disk (which cost several hundred dollars) and special software.

    If it starts to read, track zero is probably ok. It may NOT be alignment, but could also be bad/sticky worm drive bearings.

    Are you able to provide a video of it's behavior ?

    Do you have more than one boot floppy ?
     
  10. mikemike690 thread starter macrumors regular

    mikemike690

    Joined:
    Apr 7, 2012
    Location:
    New Zealand
    #10
    Ohh crap, I'm busy for the next few days but when I last saw it, it did start to read I think. I'll upload one when I get some time and I don't think so, I don't even really know what those are to be honest, I inserted a MacPaint one and it booted to the desktop then it blew that part. Thanks.
     
  11. maczo macrumors newbie

    maczo

    Joined:
    Dec 25, 2014
    Location:
    Italy
    #11
    Did you unscrew the track0 sensor when you repaired the wirings?
    If yes, you need to realign the track0 sensor. The fixing screw allows for some adjustments. I usually do this with a trial and error approach. It's a long process but eventually will give good results.

    1. take a known good floppy disk (be sure that it reads correctly on another, working, floppy drive)
    2. Unscrew the track0 sensor very very slightly (just slightly enough to be able to move the sensor from its current position)
    3. Move the track0 sensor in one direction very very very slightly (about 1/4 mm or even less)
    3. Tighten the fixing screw again
    4. Try if the floppy reads, if not repeat from step 2 by moving in the same direction as before

    Note: At step 3, when trying to move the track0 sensor, if it cannot go any further, invert the direction of the movement

    Sometimes, you have to try both directions many times to finally hit the "hot spot".It's a long process, but I never had a miss. Unless, of course, the drive has other kind of problems. But I usually try this method at first before messing with the heads.

    Good luck. ;)
     
  12. mikemike690 thread starter macrumors regular

    mikemike690

    Joined:
    Apr 7, 2012
    Location:
    New Zealand
    #12
    Thanks for the help guys, I managed to bend the leaf slightly and it now gives the happy Mac. Once again thanks for your help
     
  13. maczo macrumors newbie

    maczo

    Joined:
    Dec 25, 2014
    Location:
    Italy
    #13
    Good to hear that you solved the problem. BY the way, what do you mean with "bend the leaf slightly"?
     
  14. MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #14
  15. maczo macrumors newbie

    maczo

    Joined:
    Dec 25, 2014
    Location:
    Italy
    #15
    Oh yes, I used this tip before.... It works! I also used to shorten other springs of the automatic inject mechanics
     

Share This Page