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Thread: Mac Plus video issue

  1. #1
    Join Date
    Oct 2016
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    Cincinnati, Ohio USA
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    426

    Default Mac Plus video issue

    I just picked up a Mac Plus cheap. No keyboard or mouse. Insides look fairly clean so I turned it on. I get a vertical bar about 1/2 inch wide that does look to have an image in it. The computer gives one long beep when turned on. I tried putting a System 6.07 options disk in it and turning it on. The drive doesnít do anything. Maybe I need a mouse or keyboard before trying that? It looks like some of the solder joints are fresh especially around the transformer that the high voltage cable comes out of. Please help me fix this.
    PCjr, DTK PC-XT Turbo, 386DX 33, 486 laptop, Pentium 120, Pentium III 500, various old laptops, Commodore Colt, all working. I also have a 286 that I need to see if I can repair.

  2. #2
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    Apr 2018
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    Los Angeles, CA
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    I've posted these before but it's always worth reposting:

    Classic Mac Repair: http://www.ccadams.org/se/classicmac2.pdf
    Dead Mac Scrolls: https://archive.org/details/TheDeadMacScrolls

    The Dead Mac Scrolls has pictures that will guide you to your possible issue and possible solutions. I've not had your exact issue but if others have, then i'm sure they'll comment as well. As for the Mouse and Keyboard, they don't matter for a working system. When I was repairing mine I didn't have a working keyboard. I did have a mouse but not hooked up. The sad part is that finding a cheap mac plus is easy, finding an affordable keyboard to go with said computer is going to be the challenge. You'll likely pay more for the keyboard and mouse then you did for the computer itself.

    The drive should do something, but if it's been sitting, it's almost guaranteed that you'll need to open it up and oil most of the moving parts. The mac drives used this grease that basically turns to concrete over time so lots of oiling and moving parts around might help that. Assuming it works at all. Obviously cleaning the head while you're at it.
    -- Brian

    Systems: Amstad PCW 8256, Apple IIe/II+/Mac+/Mac 512k, Atari 800/520STFM, Commodore 64/Amiga 3000/PET 4032/SX-64, IBM PS/1 2121-B82, Kaypro II, Osborne 1, Tandy 1000 SX, TI-99/4A, TRS-80 Model 4 GA

  3. #3
    Join Date
    Oct 2016
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    Cincinnati, Ohio USA
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    Default

    Thanks. I actually found those two after I posted. My first try seems to be re-soldering a connector and the coil for width adjustment. I also have to find my plastic tool for adjusting coils. I was afraid it was the fly back transformer, but that isn’t one of the suggestions for my symptom. If I can get the display working, I will pull the drive and work on it. I have cleaned and lubricated drives before, so that shouldn’t Be a problem. Yes, buying a mouse and keyboard are likely to be much more than the $25 I paid for the Mac, but worth it if I get it working. If I can’t fix it, I won’t need them. LOL
    PCjr, DTK PC-XT Turbo, 386DX 33, 486 laptop, Pentium 120, Pentium III 500, various old laptops, Commodore Colt, all working. I also have a 286 that I need to see if I can repair.

  4. #4
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    Oct 2016
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    Cincinnati, Ohio USA
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    I took another look. Capacitor C1 has a definite bulge. So I guess I order a replacement and start there.
    PCjr, DTK PC-XT Turbo, 386DX 33, 486 laptop, Pentium 120, Pentium III 500, various old laptops, Commodore Colt, all working. I also have a 286 that I need to see if I can repair.

  5. #5
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    Apr 2018
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    Los Angeles, CA
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    Quote Originally Posted by KenEG View Post
    Thanks. I actually found those two after I posted. My first try seems to be re-soldering a connector and the coil for width adjustment. I also have to find my plastic tool for adjusting coils. I was afraid it was the fly back transformer, but that isnít one of the suggestions for my symptom. If I can get the display working, I will pull the drive and work on it. I have cleaned and lubricated drives before, so that shouldnít Be a problem. Yes, buying a mouse and keyboard are likely to be much more than the $25 I paid for the Mac, but worth it if I get it working. If I canít fix it, I wonít need them. LOL
    That was my thinking as well which is why I didn't bother finding a keyboard til i fixed it... and when i did find one, it didn't work. Eventually found a few locally that took care of the 512k and the Mac Plus I have. I mostly did adjustments the 'lets try and not kill myself' method, with the exception of L2 because you need to do that with a special tool or with the machine off (I chose the later since I didn't have a tool or the inclination to make one). Though your issue doesn't sound like an adjustment problem. I found following the info in the classic mac repair first will get all the basic issues out of the way and get things calibrated, then follow the dead mac scrolls f you still have specific issues that didn't get solved in the earlier troubleshooting.

    Quote Originally Posted by KenEG View Post
    I took another look. Capacitor C1 has a definite bulge. So I guess I order a replacement and start there.
    Ironically I've had C1 look kinda bad on both of mine and still work fine. It's not something I had in stock so I didn't bother looking for a replacement since my board worked anyway, but it is a common issue from what i read. That said, if you have to get capacitors anyway, you might want to replace the RIFA's at C38 and I believe C37 / C33... assuming it's not a newer board or they've never been replaced (still gold plastic covered paper caps). Replacing won't fix any of your issues but worth doing if you're working on the board anyway and will keep family members from disowning you when they blow.
    -- Brian

    Systems: Amstad PCW 8256, Apple IIe/II+/Mac+/Mac 512k, Atari 800/520STFM, Commodore 64/Amiga 3000/PET 4032/SX-64, IBM PS/1 2121-B82, Kaypro II, Osborne 1, Tandy 1000 SX, TI-99/4A, TRS-80 Model 4 GA

  6. #6
    Join Date
    Oct 2016
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    Cincinnati, Ohio USA
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    OK, I will look at the RIFA caps, but I tend to only replace what id needed to get them working. Maybe as I gain confidence in my abilities I will do more. I'm not sure what C1 does, but if it is causing low voltage in the horizontal sweep circuit, it would explain my issue. The solder joints for it are definitely newer than most of the board. Someone has worked on this before. The capacitor looks the same as the one next to it, so maybe someone refreshed the solder joint but didn't replace it.
    PCjr, DTK PC-XT Turbo, 386DX 33, 486 laptop, Pentium 120, Pentium III 500, various old laptops, Commodore Colt, all working. I also have a 286 that I need to see if I can repair.

  7. #7
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    Oct 2016
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    Cincinnati, Ohio USA
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    What is the difference between a high frequency capacitor and a regular one. The first ones I ordered say bipolar, but not high frequency. Through a lot of googling, I discovered that I really wanted a horizontal deflection high frequency capacitor. I ordered one of those at a price that was similar to 5 of the regular bipolar capacitors. Is this a difference in ESR?
    PCjr, DTK PC-XT Turbo, 386DX 33, 486 laptop, Pentium 120, Pentium III 500, various old laptops, Commodore Colt, all working. I also have a 286 that I need to see if I can repair.

  8. #8
    Join Date
    Oct 2016
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    Cincinnati, Ohio USA
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    I decided to try a couple of things today. I unplugged and checked the yolk connector J1. It looked OK. When that didn’t change anything, I reflowed solder joints on the width adjust coil, J1, and the flyback transformer. Again, no change. I tried adjusting the width with the computer off since I don’t have a non-metal tool right now. I can change the width a little. Does this rule out the coil as a potential cause?
    PCjr, DTK PC-XT Turbo, 386DX 33, 486 laptop, Pentium 120, Pentium III 500, various old laptops, Commodore Colt, all working. I also have a 286 that I need to see if I can repair.

  9. #9

    Default

    Quote Originally Posted by KenEG View Post
    I decided to try a couple of things today. I unplugged and checked the yolk connector J1. It looked OK. When that didn’t change anything, I reflowed solder joints on the width adjust coil, J1, and the flyback transformer. Again, no change. I tried adjusting the width with the computer off since I don’t have a non-metal tool right now. I can change the width a little. Does this rule out the coil as a potential cause?
    If you don't have a plastic tool handy you can use a wooden BBQ skewer. I just whittle down the end until it fits snugly.
    System 80 Expansion Interface located! Thanks to all who helped out and the good people in the NZ vintage computer forums!

  10. #10
    Join Date
    Oct 2016
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    Cincinnati, Ohio USA
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    Default

    Thanks for the information. I have the tool around here somewhere and I just ordered a full plastic tool set today.
    PCjr, DTK PC-XT Turbo, 386DX 33, 486 laptop, Pentium 120, Pentium III 500, various old laptops, Commodore Colt, all working. I also have a 286 that I need to see if I can repair.

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