Mac Plus screen repair

Discussion in 'Apple Collectors' started by daniel-b, Mar 20, 2012.

  1. daniel-b, Mar 20, 2012
    Last edited: Apr 1, 2012

    daniel-b macrumors member

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    Jan 27, 2012
    #1
    Hi all,

    The same attic that contained my Powerbook Duo also contains a Mac Plus.

    This computer has been in my attic for 10 years, I can hear it booting, but the screen is completely dead.

    It has an external hard disk but is missing a mouse.

    How likely is it that the screen problem is an easy fix like replacing a fuse or something? I don't have the skill to make a complex fix myself, and I don't want to spend a lot of money on it.

    Thanks,

    Daniel
     
  2. MacTech68, Mar 20, 2012
    Last edited: Mar 20, 2012

    MacTech68 macrumors 68000

    MacTech68

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    #2
    If the machine attempts to boot and the screen is entirely dark, there are two possibilities:

    1. The brightness control under the front edge is turned all the way down, or

    2. A dry and cracked solder joint on the video & power connector which is approximately in the center of the "Power/Sweep" or "Analog Board".

    Give the machine a thump on the left side (when viewed from the front) whilst it's running and see if the picture intermittently flashes up. If it does, it will be a simple re-soldering job.
     
  3. daniel-b thread starter macrumors member

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    Jan 27, 2012
    #3
    Thanks!

    I'll take a look and see if I can see anything.


    D.
     
  4. Macman45 macrumors demi-god

    Macman45

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    #4
    Keep us posted...I love old Macs coming back to life!
     
  5. daniel-b thread starter macrumors member

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    Jan 27, 2012
    #5
    You're not gonna believe this - I gave it a good thump on the left-hand side, and it's been working ever since! The screen is a little smaller than it is supposed to be, I think, but it is stable.

    I even mnanaged to get it to boot from it's 20-year-old hard disk, It says 20SC on the HD BTW, does that mean it's a 20MB disk?

    There's not much you can do with it without a mouse, so the next thing is to get one.

    I can hardly believe it ....
     
  6. MacTech68, Mar 21, 2012
    Last edited: Mar 21, 2012

    MacTech68 macrumors 68000

    MacTech68

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    #6
    :)

    Cool. Don't be surprised if the picture disappears suddenly. ;)

    Yup, 20SC is 20MB.

    The mouse may be a little difficult. An old PC serial mouse will NOT work. :(

    There's a few on eBay: http://www.ebay.com/sch/i.html?_nkw=mac+plus+mouse

    The screen size is probably adjusted as per the specs in the service manual. The border was always quite large looking IMHO.
     
  7. daniel-b thread starter macrumors member

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    Jan 27, 2012
    #7
    Well, obviously the loose connection is still there,but this does mean that we know what the problem is, and that it's easily fixable. What I really couldn't believe was how everything still works after being junked and spending 10 years in my attic.

    You tend to forget how slow the old disks were, and how noisy. When you run the old stuff in emulators it runs really fast .. . . .
     
  8. MacTech68 macrumors 68000

    MacTech68

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    #8
    Yup, just remember that there is a small trap with that video connector.

    It's keyed by having one pin removed (2nd pin location from one end). this leaves the video pin (often the one that causes this fault) sitting out by itself and is often missed when these boards are re-worked. I saw quite a few like this.

    :)
     
  9. thagomizer macrumors 6502

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    #9
  10. ivnj macrumors 65816

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    Dec 8, 2006
    #10
    I found a apple II adb mouse at my good will store for 2 dollars so keep looking.
     
  11. daniel-b, Apr 1, 2012
    Last edited: Apr 1, 2012

    daniel-b thread starter macrumors member

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    #11
    Hi all,

    My mouse arrived in the mail today, so I was able to use my Mac Plus for the first time. It came on OK, although it needed a little gentle persuasion to display the screen stably. Once it was stable, however, it stayed rock solid, and I'm really wondering whether it is worth getting it fixed - I have found someone who is willing to do it, but there is always the risk that he'll muck it up. I am thinking of waiting till it won't come on at all any more, and then getting it seen to; it's not as if I'm actually going to use it for anything, after all.

    Anyway, here are some pictures that I thought you may find interesting.

    It is interesting because the system is in Hebrew:

    Here is the Mac in all its yellow and grimy glory. The mouse is brand new and a completely different color:

    [​IMG]

    A menu in Microsoft Word with the key commands on the wrong side:

    [​IMG]

    The finder version. What system is this?:

    [​IMG]

    The control panel in Hebrew:

    [​IMG]

    The Rav Ktav Hebrew word processor:

    [​IMG]

    ----------

    One more picture - the startup screen. It says "Macintosh at your service"

    [​IMG]


    PS. The diskette drive does NOT work...
     
  12. daniel-b thread starter macrumors member

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    Jan 27, 2012
    #12
    Hi all,

    Here are some more Mac Plus pics:

    I've had the Mac apart to work on the floppy drive (and something is not working right, see separate thread). While I was in there I took some photos:

    Grimy motherboard. I'd like to clean it up, but since it seems to work perfectly, I don't want to do something drastic like putting it in the dishwasher, Any suggestions as to how to clean it?

    [​IMG]

    Inside the Mac, sans motherboard:

    [​IMG]

    The analogue board:

    [​IMG]


    The Mac with his wizkid grandson. Neither of these two Macs has a floppy drive, at the moment:

    [​IMG]

    Finally, this Mac is running System 4.1. this is the oldest system I've ever used (except on emulations). Here is Switcher:

    [​IMG]
     
  13. MacTech68 macrumors 68000

    MacTech68

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    Australia, Perth
    #13
    You could try an air compressor and a long, soft-bristled brush.
     
  14. daniel-b, Apr 13, 2012
    Last edited: Apr 13, 2012

    daniel-b thread starter macrumors member

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    Jan 27, 2012
    #14
    Hi,

    I'm a little puzzled by this screen issue.

    It's getting better. The screen always comes on. All that's left of the issue is a little shimmery effect when the machine is stone cold, that goes away as soon as it warms up. It even works when it's standing on top of the HD. At first the vibration made the screen flash like crazy.

    Is it conceivable that the issue was not caused by a cracked solder, but by dirt and dust which I partially cleaned off when I dismantled the computer and which is gradually burning off as I use it?

    I can't imagine that a cracked solder would gradually heal itself; I've certainly never seen similar issues get better in other devices that I own, like old electronic musical instruments.

    EDIT: This Mac stood idle for nearly 20 years. I can find no evidence that it was use after 1994. It presumably stood for 10 years in an office at the university, and then since about 2004 in my attic.
    This what killed the floppy; the amazing thing is that everything else works, including the old hard disk and the original keyboard.
     
  15. MacTech68 macrumors 68000

    MacTech68

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    #15
    Yes, but it's misleading. Every time you see a slight shimmy, the cracked solder joint is arcing. This is referred to as a "hot joint". Generally, these will worsen over time as the arcing burns away more solder. Flexing these hot joints will often give the appearance of improving if the flexing allows more contact surface area.
     
  16. daniel-b thread starter macrumors member

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    Jan 27, 2012
    #16
    Thanks.

    It's definitely past time I learned how to solder. I've done electrical soldering in old cars, but nothing delicate like soldering in a computer.

    D.
     
  17. daniel-b, May 4, 2012
    Last edited: May 4, 2012

    daniel-b thread starter macrumors member

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    Jan 27, 2012
    #17
    Hi all,

    This afternoon I took a large dose of brave pills, and soldered the video pin on my Mac Plus's analog board. As far as I can see, it's now working perfectly :) The screen is stable and perfect.

    Thus far I've only gone as far as the flashing disk icon.

    Next step is to prepare a boot zip disk for it on my Quadra, and see if it can be an alternative to the large, noisy and heavy SC20 hard disk.

    I am extremely chuffed . . . .

    D.


    PS. I have not yet replaced the cardboard on the analog board; I thought I might leave it off to see if it continues to work OK or if I need to do some more work. Is this a problem?

    Edit: I got the Mac Plus to boot from the zip disk into System 6.0.8, and I got the Quadra to work with my 24" Samsung monitor. Wonders never cease . . .
     
  18. MacTech68 macrumors 68000

    MacTech68

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    Australia, Perth
    #18
    Excellent work. Glad to hear it's working better.

    I would re-fit the insulating card on the analog board. If it was held on with double-sided tape, you can purchase the 'snap-rivets' to refit it via the holes instead. Richo SR series rivets were used later. I just can't remember which size fits the hole. RS-Components sell Richo SR Snap rivets. They are re-usable by lifting the head of the rivet.
     
  19. daniel-b thread starter macrumors member

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    Jan 27, 2012
    #19
    Thanks.

    I was going to use new double sided tape, which is why I was going to leave it off till I'm sure it's working OK (I was going to stick it on when I install the floppy drive, which I will be receiving soon).

    The double sided tape tends to stay stuck once you stick it and I didn't want to have to take it off again any time soon.

    D.
     
  20. daniel-b thread starter macrumors member

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    Jan 27, 2012
    #20
    A couple of pictures:

    My desk; three keyboards, three mice, two computers. Note the zip drive on top of the Mac PLus and System 7.6 on the 24" monitor:

    [​IMG]

    THe Quadra is under the desk:

    [​IMG]
     
  21. daniel-b, May 6, 2012
    Last edited: May 6, 2012

    daniel-b thread starter macrumors member

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    Jan 27, 2012
    #21
    Hi all,

    I just killed my Mac Plus :(

    It became obvious to me that my previous soldering had not in fact solved anything, so I went in and soldered the rest of the power plug contacts. This went smoothly, with a new soldering iron.

    When I turned it on it was still flickering, so I basically opened it up and then closed it again. When I plugged it in there was a loud pop and then silence.

    I think what has happened is that a tiny drop of sweat fell unnoticed on the back of the analog board, and this killed it.

    I retrieved a very black and dead fuse from the machine. What are the chances it might be revived? There is no visible (to me) damage and there was no smoke or smell of burning.

    Needless to say I am pretty pissed off at myself for killing my computer in such a silly way after it survived my efforts at soldering it. It does seem that the soldering didn't help, so I am wondering what the problem was...

    THanks,

    Daniel
     
  22. MacTech68, May 6, 2012
    Last edited: May 6, 2012

    MacTech68 macrumors 68000

    MacTech68

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    Australia, Perth
    #22
    Bummer. I feel really bad for you, (and a little responsible). :(

    A little trick with glass fuses. If, when it blows, the inside of the glass is blackened and splattered, then there is a lot more wrong than just the fuse. Something has more than likely shorted. Replacing the fuse under these circumstances is likely to do more damage.

    If you can see through the glass, and can see the ends of the fuse wire with a gap in the middle, generally, the fuse can be replaced.

    Unfortunately, in your case, it seems that there is more damage here, and I am sorry that I suggested attempting to re-solder it (if indeed this caused the damage).

    It is possible, that the work you did DID NOT cause the problem, as these analog boards were not known for their reliability.

    EDIT: if you didn't have the insulator card fitted, it could be worth while checking for black marks on the inside of the rear case that faces the analog board. Unfortunately, without at least a multimeter, diagnosing this failure will be near impossible. :(
     
  23. daniel-b thread starter macrumors member

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    Jan 27, 2012
    #23
    Hi,

    Thanks for replying.

    As I said before, I believe that what made the fuse blow is that the board got a drop of sweat on it. I do not think my work killed it. I do not however believe that my work fixed it either.

    I think the drop of moisture caused a short. I cannot see any other signs of damage (if this means anything).

    Thanks,

    Daniel
     
  24. daniel-b, May 7, 2012
    Last edited: May 7, 2012

    daniel-b thread starter macrumors member

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    #24
    Don't. I blew the damn computer up, not you.

    Here are some pics. I do have a multi-meter, and I know how to use it. I once rewired an entire car.

    The card was in when it blew. Here is what it shows.
    [​IMG]

    The marks in the circle are new, and they correspond to where the analog got wet. The rest were already there before.

    Here is the analog board at the area corresponding to the new mark:

    [​IMG]

    Perhaps more interesting, here is the area corresponding to the old black marks:

    [​IMG]

    Finally, for what it's worth, here is my soldering work:

    [​IMG]

    [​IMG]

    Ideally, I would like to get this machine going, but if I've killed it, then I will view it as a learning experience.

    Thanks for all your help,

    Daniel
     
  25. iMacC2D, May 7, 2012
    Last edited: Aug 12, 2017

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