Classic Troubleshooting

Discussion in 'Apple Collectors' started by bunnspecial, Nov 17, 2015.

  1. bunnspecial macrumors 603

    bunnspecial

    Joined:
    May 3, 2014
    Location:
    Kentucky
    #1
    I bought a lot of Compact Macs the other day, and between the three(512Ke, SE 800K, and Classic) the least interesting and least valuable one seems to be the one getting the majority of my attention :) . To be fair, the other two work fine, and are more or less dupes of computers I already have(I have a 512Ke and an SE FDHD).

    In any case, when I went to pick up the computers the seller powered them all up, and I was greeted by a "scrambled" pattern on the screen of the Classic along with no boot tone.

    I've been tinkering with it the last few days, and was able to first get it to single vertical lines followed by a checkerboard pattern and now, finally, the standard gray start-up screen. It will not, however, progress anywhere past this-I don't get a boot tone, a cursor, or Happy Mac/floppy disk. As best as I can tell, when I plug in the hard drive the computer sounds like it is accessing it. I also occasionally get some static-type sounds from the speaker.

    I've scrubbed the logic board with soapy water, rinsed with deionized water, and dried thoroughly. This was what got me to the gray the screen. I also tried washing with 100% isopropyl alcohol, and after drying the result was the same. There's no visible leakage from the caps on the logic board, although it did have a corroded battery in it.

    I do have the RAM expansion card. The status of this card(removed, installed, SIMMs installed or removed) doesn't change the operation of the computer.

    I can force a "sad mac" by pressing the rear button on the side of the logic board, and then reset it with the front button. These are the only things I can get the computer to do.

    Any thoughts on where I can go from here? Even though the Classic isn't a particularly exciting computer, I want it to fill out my Classic collection and am also intrigued by its ability to boot from ROM.
     
  2. MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #2
    Even though the caps look like they haven't leaked, they probably have.

    However, you could try gently heating the motherboard to warm up the caps. Before the caps fail completely they usually work after a warming up with a hairdryer.

    You may want to check the tracks on the board for any that have black spots on them. That would indicate corrosion/etching by electrolyte.
     
  3. havokalien macrumors 6502a

    havokalien

    Joined:
    Apr 27, 2006
    Location:
    Kelso, Wa
    #3
    mactech is 100 percent correct. I have a few classics and the motherboards rank worst to leakage right next to the LC line.
     
  4. weckart macrumors 68040

    Joined:
    Nov 7, 2004
    #4
    I have a Classic with so much leakage and corrosion that I am not even bothering to resurrect it. Probably would be a better use of my time to source a spare logic board for it from a Classic with a bust screen.
     

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