68kMLA Classic Interface
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| Are There Foreseeable Problems (Currently) or Likely in the Near Future With This Analog Board? | |
| Posted by: butch on 2024-09-10 14:06:46 Okay folks: This is my first attempt to diagnose and repair (if necessary, but only if necessary) any apparent defective (or soon likely to become defective or fail) parts on a Mac Plus original analog board. Right now, the analog board is working (it's powering and providing signal to) a Mac Plus (1988) that I purchase for $200 ($100 plus $100 shipping) that originally had a Sad Mac ROM failure black screen. I put in new ROMs, upgraded the logic board to 4 MB and the sad Mac turned very happy and booted beautifully. The logic board is in near pristine condition, and other than the defective ROMS which have now bee replaced and the board upgraded to 4 MB, everything runs smoothly and without any hiccups. The screen is perfect, no pixel failures or fade lines or other problems and the only tiny weeny issue is a barely imperceptible difference in the width between the left black margin and the right black margin. The other issue is that the internal floppy drive, which works beautifully and accepts disks and reads them faithfully, is reluctant to let go of disk when we attempt to eject the disk and needs to be prodded with a push pin. That's in the process of being fixed and we're sure that a fully functional drive will be fully repaired in short order. No worries there whatsoever. However, what we could really use some help with is the analog board. While the analog board is fine and both powers and provides signal to the Mac Plus at the present time, we see that its the original analog board and doesn't appear to be in quite a near perfect condition as the logic board. While is is fully functional, we're worried that, perhaps, just perhaps, one or more capacitors may be nearing its end of life and need to be replaced and repaired. We've provided a bunch of pictures to give you a better idea of what condition its currently in. Would it be too much to ask you folks to take a look and let us know if you see things wrong with the board that needs repairing before we attempt to sell the re-assembled Mac Plus to some poor, unsuspecting buyer. We always want our customers to be happy and never want them to be sad with any purchase they make from us. Thank you for taking a look and pointing out anything you observe that may need attention. Sincerely, Butch Attachments
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| Posted by: falen5 on 2024-09-10 14:55:31 Hi In terms of selling on a vintage machine there is allot less to worry about regarding future possible failures. It is a 40 year old , vintage machine. The potential buyers already know this. You could simply list the machine as "fully working , not recapped" and then you are covered from future failures. Again any potential buyers would know this. Nobody gives guarantee's with vintage machines , at least I have never seen any. As for its present condition , Yes , it should be fully recapped to ensure its continued functioning. These capacitors get weaker with age , can leak their electrolite and go out of spec. Again this is already known by any potential buyers. Get the floppy working , put it all back together and put it up for sale with a title like " Mac Plus , stripped and cleaned , floppy stripped and cleaned, Machine working 100% - Machine has NOT been recapped " ....." Bought as is , no guarantee " This will protect you from any possible future failures. If you have a look on ebay this is exactly how many vintage machines are listed And again any potential buyers will be aware of this and will accept these terms , even if the machine fails a day after they receive it. It is simply the reality of the hobby | |
| Posted by: falen5 on 2024-09-10 15:03:11 and in the interests of safety , tell us you understand the dangers of the high voltages on that analog board you know and have correctly discharged the high voltage before you removed that analog board I assume you have but just have to keep asking people if not , say so ....... it is very important for your health cheers | |
| Posted by: cheesestraws on 2024-09-10 15:49:29 Echoing strongly what @falen5 says - if you are not comfortable working in old power supplies, do not muck with the analogue board. I don't use bold text often but this is important. Several of the big capacitors don't have bleeders (IIRC) and one of the heatsinks is live when the board is powered. If you are comfortable working with mains voltages, take this as a warning that the PSU section of this board is not particularly friendly and lacks modern safeties. The main problem you may see with those boards is that the PSU is chronically underspecced - the designers didn't take into account (possibly because the state of the art then just wasn't what it is now) that switching power supplies play merry hell with components. Also, because Jobs was so hot (geddit) on not having a fan, the boards basically bake themselves, and this makes the caps dry out. So replacing the caps might not be a bad idea, if and only if you can do it safely, but bear in mind that the failure mode you're guarding against here isn't the same failure mode as makes one recap later logic boards and failed capacitors in these analogue boards in my experience rarely take out other components on the board. So it's a bit safer to leave it as it is than LBs are. | |
| Posted by: falen5 on 2024-09-10 18:38:14 so you know how to discharge it - great - good luck | |
| Posted by: butch on 2024-09-11 06:22:09 Thank you sooooooo very much!!! You guys are great! That's what I love about the old Mac and Hackintosh communities, the care and dedication and willingness to share!!! Thanks again! | |
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