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tattar8

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  1. Update: I opened one of the first two's eject mechanism gear box, removed the gears, and found that it was just stuck, even though the grease wasn't that bad. I re-greased it and put it back together and now it's good as new. I also lubricated the third one's drive tray, and cleaned it with IPA, so now it's able to accept a disk properly, but any disk I insert immediately results in an unreadable disk message within a second (so too fast for it to actually have read the disk). It also couldn't eject similar to the other two. I opened up the gear box and found that it was in severe need of new grease, but when I went to take it apart to clean out the old grease, the infamous yellow gear just fell apart the second I touched it with my tweezers. So now I need to get a new gear. I have been meaning to buy a 3D printer, so maybe this is the time...
  2. I wasn't sure where to post this as this spans Mac categories (these drives came from a II-series, Portable, and SE/30). I have 3 drives that are dead and am wondering if any of them are likely to be fixable, or if I should just toss them and not spend hours on a futile effort. Two of them exhibit the same symptoms -- they seem to work (but need a head cleaning), but will not eject. I would suspect the infamous eject gear, but I don't hear any indication that the eject motor is even spinning. Is this some simple fix, like a capacitor that needs replacement or something? The third is a drive that is very dirty and needs serious cleaning and lubrication, but also makes a constant hum when the Mac is powered on, with or without a disk. The drive motor does spin, however. Any ideas?
  3. The Mac now boots. Swapped all the capacitors and she fired right up. This machine came with a Supermac video card (looks like a Spectrum/8 Series III), but I had to swap in a Mac II video card since the Supermac was having trouble with the monitor I'm using. The hard drive (looks like an aftermarket Quantum) is totally dead, which is no surprise, but I have a spare SCSI2SD to throw into it. The bigger issue is the floppy drive, which seems to be in bad shape. It needs to be cleaned and lubricated, which I can do, but what I'm not sure about is the fact that it makes a constant hum when the machine is powered on. If you insert a disk it does not read, but the disk does spin. Any idea how to fix that? Or another spare drive I have that doesn't seem to be able to eject?
  4. I’ll check to see if there was over voltage on the 12v line; I should be able to power on the supply without the logic board if I just provide +5V from USB or something, right? These were the factory tantalums, so they shouldn’t be under specced.
  5. In that case I'll wait; the caps will probably show up this week, so I don't save a lot of time by trying to boot the machine now. I did desolder C1 (far more easily than I expected) and found that the pads underneath were pristine. Could it be because C1 is the only one on the 12V rail? All the others are on 5V I believe.
  6. I recently acquired a IIfx that was sold as totally dead. When it arrived, first thing I did was remove the old batteries and swap in new ones (since this machine won't power on without them). I then tried to turn it on. Clearly the batteries were the cause of the "totally dead" issue, since it immediately powered on. However, within seconds (so don't know if it chimed yet) C1 exploded with a bright flash and released its magic smoke; this board was already populated with tantalums. I immediately yanked the power cord and shut the machine off. According to the schematics, C1 is supposed to be between the +12V rail and ground, so unless I'm mistaken the only thing it could have affected is the (probably already dead) hard drive and the floppy drive. I had already ordered a full set of replacement capacitors, but those haven't arrived yet. In the meantime, I have 2 left over from the last time I did a recapping project. Can I safely just swap the blown one and try to power up the machine again, or should I wait until the rest come and recap the whole board first?
  7. tattar8

    GCC on A/UX?

    There's an entire archive of A/UX software that gets installed under /usr/local kicking around somewhere. It includes a bunch of GNU tools including GCC. I just FTPd it to the box and untarred it there. It's here: ftp://ftp.atlas.altexxa.net/software/mac/unix/robbraun/aux-usr.local-10172010.tar.bz2
  8. tattar8

    Corroded Chip

    When you say it's behaving weird, what exactly does that mean? You get signs of life out of it but it behaves erratically? If you even get a chime (either kind) out of it I'd think that eliminates the CPU as being the problem. I have a IIci with what I believe to be a dead 68030, and that's because it does nothing at all after poweron -- no chime, nothing on the address lines, etc, even with a good system clock.
  9. tattar8

    Corroded Chip

    Yes, that notch is there to mark Pin 1.
  10. tattar8

    LCIII battery 'splosion

    That software can read old unknown ROMs? Last time I tried I wasn't able to make it work either, trying to read a ROM out of some old 6502-based terminal I was messing with. For that thing I ended up just wiring up a microcontroller I had laying around.
  11. tattar8

    Macintosh 128k replacement went (almost) perfectly!

    On my board, the 74LS253 was installed on a little PCB attached to a header. I just removed it and used a jumper to jump the two pins that corresponded to the cut trace. Now as far as the Mac is concerned, it's back to only having 128k.
  12. Do you know of any ready-made development boards for Atmel/Microchip's CPLD lines? I can't find any, and I really don't want to spin my own board for one at this point. I built a circuit based on the VHDL code that generated the waveform I posted earlier, but while it didn't stop the machine from booting normally, it still didn't allow larger RAM sizes. @Bolle Did I completely overcomplicate this? Does the GAL's logic for the WE not worry about CAS-before-RAS at all, and instead just holds WE high whenever RAS is high regardless of what CAS is doing? So this whole thing boils down to simply "RAS * WE", which I can just build using a single AND gate?
  13. tattar8

    Macintosh 128k replacement went (almost) perfectly!

    Nice! So you downgraded the 512k back down to 128k? I just got my hands on a 128k that has also been upgraded, and trying to figure out what I need to do to reverse the upgrade. What did you have to do?
  14. The Mac II has separate CAS and RAS lines going to each SIMM. Does that mean that all the banks are getting refreshed independently? Or can I assume that while accesses may occur at different times, the CAS-before-RAS refresh will always be synchronized? If they're completely independent, then I'll need to build the whole design 4 times, which would make it impractical to just use 74 series logic, and instead actually find a CPLD or FPGA and appropriate level shifting hardware (since all the ones I can find run at 3.3v).
  15. Could I just throw a series of noninverting buffers on the /weout to introduce some propagation delay?
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