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cj_reha

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  1. cj_reha

    CJ's miscellaneous finds

    No, sorry - prices for Color Classics are insane these days, and I'd be afraid I wouldn't be able to find another reasonably-priced unit. I plan on hanging on to it for a while.
  2. cj_reha

    CJ's miscellaneous finds

    Apologies for the very late post, but here's the other 512K I picked up a little while back. This one is pretty beat up and obviously led a hard life...it's never a good sign when you open the package and immediately get a whiff of nicotine. Gross. I bought this machine as it, like the 512Ke with the Mac Rescue upgrade, had a visible SCSI port installed in the battery compartment; inside, I discovered a Dove MacSnap 548S 2 MB RAM board, with the matching SCSI upgrade. The machine had also been upgraded with an 800K drive, presumably installed when the original ROMs were replaced. When I power tested it, it displayed the normal flashing disk icon, but also whined quite loudly and did not have any sound. After an analog board recap and cleaning of the audio jack on the logic board, I was able to get it up and running well again. My next conquest post will be about yet another 512K, but with a very special and rare upgrade that, in my opinion, is cooler than any of the other stuff I've posted about in this thread..more to come soon!
  3. cj_reha

    Molar Mac!

    Sweet find! Praying that the flyback stays good for many years to come...
  4. cj_reha

    CJ's miscellaneous finds

    It's been a little while since I last embarked on any conquests, but recently a pair of packages came in the mail bearing gifts! Namely a pair of 512K's with some neat upgrades. The first system that arrived is a 512Ke with a Computer Care Mac Rescue RAM/SCSI upgrade board installed. This is, in my opinion, one of the most useful upgrades one could get for a Mac of this vintage. It allows the user to upgrade a 512K to up to 6 (!) MB of RAM - 4 MB for the system, and 2 MB for a RAM disk that could be configured in software (although, unfortunately, this software is nowhere to be found these days ). It also adds an aforementioned 25-pin SCSI port in the battery compartment. My Mac Rescue board came with 1.5 MB installed, bringing the system to a total of 2 MB of RAM. I find it interesting that the SIMMs installed also Computer Care branded, a nice touch in my opinion. The Mac Rescue upgrade board uses the somewhat unreliable KillyKlip connector to interface with the Mac, and consequently, when I first got this unit, it only displayed a checkerboard pattern. However, a reseat of the upgrade board made it spring back to life, and it works flawlessly! The system is amazingly clean inside, and I didn't need to do any work at all to get it to work stably. Very glad I was able to find one of these interesting upgrades... its simplicity makes me think it might be possible to reverse-engineer at some point in the future.
  5. cj_reha

    CJ's miscellaneous finds

    I'm...actually not sure, sorry. I can open it up tomorrow and grab a picture of the "track" which the caddy slides into, if it would help.
  6. cj_reha

    MiniScribe arrive Lubrication Method

    Are you referring to the stepper motor that drives the heads? I've had to oil that motor to resurrect a few MiniScribes before, as the heads were having a lot of trouble trying to seek. Clock oil works like a charm for this type of thing, use a hypodermic needle and inject some oil into the motor, let it power up and seek to work the oil into the bearings, rinse and repeat. It is thankfully a pretty straightforward process.
  7. cj_reha

    CJ's miscellaneous finds

    In my vintage computing adventures, I've been acquiring more Mac-related equipment as of recent, and since this forum has a dedicated category for posting about stuff you find in the wild, why not start my own? To start off the thread, this beautiful Color Classic came in the mail today. A friend of mine is acquaintances with someone who is closing their e-waste facility, and was willing to let him sort through all the excess inventory left over at the warehouse before he sold it to other companies to get melted down. Said friend posted a picture of this system and a Classic with sticky notes advertising them as $50 each, and long story short, the guy accepted $35 for the Color Classic. Sweet! It even comes with a complementary ethernet card (which you can see in the second photo). It even has a label declaring it as property of the University of Vermont...hmmm... As the note on the front indicates, it did not power on when I first received it. Thinking that corrosion from the capacitors was probably causing the ADB ports to not work properly (and by extension, the power button on the keyboard), I gave the board a good scrubbing with isopropyl alcohol. No dice. After some more disassembly and removal of the analog board, I spotted a particularly nasty looking patch of capacitors situated right next to the yoke connector (third picture). After desoldering these caps and checking them, they all tested OK, however...I didn't trust them. Just to stay on the safe side, I perused my bag of various caps salvaged from junk boards and found suitable replacements (picture 4). Crossing my fingers and hoping for no smoke, I flipped the switch...it worked! The machine booted right to the flashing disk icon. Success! It needed a bit of convergence adjustment, but nothing else too major. I've since fully recapped the logic board and cleaned up the floppy drive, so the system is ready to go. I just need to source a SCSI hard disk for it, since the original (plus the caddy, which is an annoyance ) was removed. Disk swapping is not an enjoyable activity on any operating system past System 6 or so. However, the system works flawlessly otherwise, and I am super happy it turned out so well. More updates soon, as I have a few 512K's in the mail with some neat upgrade cards installed.
  8. cj_reha

    Macintosh Plus strange vertical/PSU failure

    Alright, I've been working on this Plus for the past few days, and some small updates: After making an incredibly stupid mistake on my part (do NOT work on computers when half asleep, kids) the analog board would no longer function at all, and immediately blew the fuse when the power switch was flipped. I eventually tracked this down to a pair of shorted diodes (CR25 and CR26, respectively), which, when replaced, caused the board to spring back to "life" (still exhibiting the mysterious symptoms, but displaying a picture as it did before). The problem is NOT the flyback or CRT/yoke - I've swapped in spare flybacks and tubes, and nothing changes. These parts are all known working, and booted up fine in another chassis. After experimenting with measuring voltages via the floppy port on the logic board, I discovered that turning up the contrast knob makes the voltage visibly drop by around a third of a volt. It only starts dropping once the horizontal bar is visible on the screen. This seems like a substantial drop, and like nothing I've ever seen before. I am still unsure as to what or where the problem component is, and any help would be greatly appreciated.
  9. Hello all - For the past few days I've been wrestling with this Macintosh Plus that has some serious analog board issues. When turned on, the system does not chime - it is completely silent. It appears to be dead, however, if the brightness is cranked up nearly to the max, a very distorted picture can be seen. It appears to be a partial vertical collapse, but on the top of the screen rather than in the middle. I've never seen a Mac exhibit this symptom before and am stumped as to where it is originating from. The small bit of vertical picture left also occasionally changes, as can be seen in one of the photos. Of note is the fact that measuring voltages through the mouse and external floppy ports, I get noticeably weak voltage - approximately 3 volts on the +5 volt rail, 8 volts on the +12 volt rail, et cetera. The floppy drive is also completely non-functional. I'm not sure if the problem here lies with the power supply or something in the video circuit. I've replaced most of the capacitors except for a few which I did not have replacements for, and those I verified with my meter to be within spec. (I did not replace C1, but it measured close enough to 3.9 uF that it seems to be fine). I've reflowed the yoke connector J1, the logic board power/video connector, and the flyback transformer solder joints and made sure they all have proper continuity. I've also tested the logic board with another known good Plus, and it boots and functions as normal. If anyone could point me in the right direction in fixing this issue, I would be extremely appreciative. Regards, CJ
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