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Found 8 results

  1. Yes, even the Macintosh 128k/512k KEYBOARD needs to be recapped: But does it really need to be 63V? Here's the keyboard schematic, with the 1uF cap showing in the upper right area nearest U2: And U2 is the 74LS123 shown here: Sure, I can find a Mouser $3.23 replacement, but why is the stock cap rated at 63V? Is it because people might be stupid and connect the keyboard to a phone jack, or is there some other reason? The reason I even wonder about this is because if lower voltage 1uF caps can safely be used in this keyboard, then more replacement options present themselves that are better and cheaper too. I look forward to your insightful replies!
  2. MacAttack

    Macintosh 128k Help

    So, I posted here about a year ago about a 128k Macintosh that I got off of craigslist. Since then I figured out that the ram was bad and replaced it. I've got to a point where the computer functions but the video has a major issue. I have been unable to find the issue so far, so here I am again! For further reference, I do have logic probes and an oscilloscope at hand if that helps fix the issue. (Before Ram Replace) (After Ram Fix)
  3. Hi - I have a 128K Mac with a Levco Monster Mac 2MB upgrade card installed in it, and somewhere over the years the covers on the EPROMs on the Monster Mac card have come off... and now the machine comes up to a sad mac icon with an error code of 0180D7; which my brief google search indicates that it's failed a ROM test - unsurprising considering the lack of UV protection on the EPROMs. I don't think the original Apple mask ROMs (they are mask ROMs, aren't they? Not EPROMs? They have no window on them...) are bad; just the EPROMs on the Levco board - so what I need is an image of that - but, the way I think the board works is it overlays the first 4K of the ROM address space with what is on the Levco board; so a standard ROM image obtained from software running on a working Monster Mac should have the data I need in it... well, I hope, anyway. So - can somebody with a working Monster Mac card run a ROM image program (such as CopyRoms http://www.gryphel.com/c/minivmac/extras/copyroms/) and post the result? Although, any other ideas would be welcome also... :b&w:
  4. I thought about putting this in peripherals, but it seemed better here since this type of floppy drive mechanism is exclusive to the 128 and 512K Mac. It is also found inside the guts of M1030 400K external floppy drives. As posted earlier (see links in this post), I have an early 128K Mac that is now fully functioning apart from the fact that it came to me with a non-working floppy drive. After a good bit of puzzling, I discovered that it was an original Sony OA-D34V 400K floppy drive (originally shipped with a stepper motor bearing the round sticker which should work in the 128K Mac with the Version A ROMs) with a stepper motor bearing the square sticker (more commonly found on the later OA-D34V-22 drives, and known NOT to work with the Version A ROMs). Since the drive itself bears a Feb 1984 production date, which predates the introduction of the square sticker stepper motor in summer 1984, I hypothesized that someone replaced the stepper motor on the drive at some point. Apple's textbook fix for this problem is to swap Version A ROMs for Version B ROMs, since Version B ROMs can read both types of drives. I have acquired a set of Version B ROMs, and the ROMs are socketed and easily swappable, so I could put in the Version B ROMs, keep the Version A ROMs stored with the machine for authenticity, and call it done. I don't intend to sell the machine anyway. But my OCD brain really wants the original type of drive in the original Version A 128K, and Science brain wants to take things apart. Frankenstein project: I have now acquired off ebay a collection of 5 400K drives, all pulled from 128K or 512K machines, all sold as non-working/AS IS (it was not totally clear to me whether the machines or the floppy drives had been tested and rated as non-working; possibly both, and I have visually examined the drives but not tested any of them yet). I paid more than I probably should have for this science experiment but I am measuring its value in hours of bench repair entertainment. The drives are a strange mix, as follows: April 84 - labeled OA-D34V - square sticker (I was disappointed to see this, as I knew one of the drives was an original OA-D34V and hoped it would have the round sticker) October 84 - labeled OA-D34V-22 - round sticker October 84 - no label where the OA label should be (?) - round sticker November 84 - labeled OA-D34V-22 - round sticker October 85 - labeled OA-D34V-22 - square sticker [this is the only "normal" drive out of the bunch] What I am wondering is this: can I remove the stepper motor from one drive and install it on another without highly specialized equipment, or will I end up with a non-aligned head mechanism that won't work on any Mac? It would be fun to rebuild my original floppy drive with a working round sticker motor. Another alternative is to see if the drives with the round sticker will work in my Version A Mac in spite of their OA-D34V-22 label. If the stepper motor is the only source of incompatibility, and Apple knew they had fixed the problem by instructing techs to install Version B ROMs in all machines with floppy drive incompatibility problems, they may have gone on for some months using up the "incompatible" stepper motor type in the Version B 128K machines they were selling up through late 1984. Nobody would ever know the difference since both types of drive worked with the Version B ROM machines. I would welcome advice on the wisdom of moving stepper motors around before I attempt radical surgery. Otherwise, I will report back here on my progress!
  5. MacAttack

    Macintosh 128k Video Problem

    Hello, I recently bought a 128k Mac (non-functioning) and the seller told me that he thought that the 74F253 Ram Multiplexers were bad. But after replacing them with new Motorola ones, the screen still has the same issue. Here is a photo: I have no idea where to got from this point and a google search came up inconclusive. Please Help!!
  6. So I got my parts for restoring my upgraded 128k. The 400k drive was completely seized up which is to be expected. But there is a problem. After lubricating the drive, it was making a continuous clicking noise. I found out that it was the limit switch that homes with head. It was to far away for the little notch to block the light. I loosend the screw holding the switch in place and moved it back a little. The drive homed properly. The drive reads and writes perfectly, But only its own disks. It will not read any disks from any other known working drive. I have multiple 400k formatted disks from my 800k drive. Not of them read, They just eject. I think that optical switch position was important as I don't think the head homes to the correct position to read the tracks. I got it to almost read one of my disks by messing with the switches position for a few hours, It almost fully booted but something was thrown off before it could finish. I connected the 400k drive to my 512ke with the scsi hard drive attached and formatted and transferred some software to its own disk. This disk reads perfectly and boots every time. The head looks brand new and I cleaned it with a q-tip and alcohol. IDK how to repair this. Its probably something really stupidly simple. How do I fix this?
  7. I got it. I am overly pleased to say the least. by the way, did I mention I got all of this for $300? everything is in mint/brandnew condition. Everything. Zero corrosion anywhere and besides the slight yellowing, its basically brand new. The mouse and keyboard, software, and the entire macintosh and carying bag are mint. The software is still sealed and also looks brand new. The motherboard is the old one with the purple ceramic CPU. The CRT is also one I have not seen yet and has a slightly more yellow tint to the picture. There is no burn in and the screen is very bright, Brighter than my 512ke. The picture is slightly warped and rotated and IDK how to fix this. It also has a Macsnap 2mb upgrade board which is awesome as I can just pop it into any 512k board and upgrade the ram without soldering. The old ram was upgraded on the board from 128k to 512k as removing the macsnap results in 512k of reported ram. The floppy drive is also the 800k drive which I want to replace with the original 400k drive and sled. If anyone has one to sell. Please email me at zastin17@gmail.com. I have not been able to get the hard drive to work but I have no idea how to use it in the first place so I will look into that. The clock battery believe it or not still has a charge. One thing I thought was odd was the dark amber colored flyback suction cup which is usually black, I think. However its definitely original as all the components used on the anolog board are from the time period and non of which have been replaced. The CRT seems to be different then anything else on the newer macintoshes and is Made by Samsung. The scsi board has the rom chips which are marked "apple 84-86" which are upgraded to obviously make the 800k drive work. Also what is the little board soldered near the ram? Anything else I should check? serial numbers ect? The crazy part is the seller lost over $100 in shipping. I paid $100 for shipping and it cost over $200 to ship. Se he only made a little over $100 in profit which I kind of feel bad as he did not know how to use ebay properly.
  8. Hi! I have a Macintosh 128K (a European version, 220V) which is converted to a 512K. It looks like just te chipset has been upgraded, but is it done by Apple (see attached photo)? The chips are branded with NEC so that makes me suspicious that it is not. Is this an original Apple-factory upgrade from 128K to 512K or is it done by someone else? Do you have any clue what the “Apple 16” sticker (round, white with red apple logo) on the large chip might mean (see photo)? Best regards, Rob The Netherlands
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