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Thread: Mac 512K with "HyperDrive" add-on: Rare?

  1. #1

    Default Mac 512K with "HyperDrive" add-on: Rare?

    Hello, everyone. I was at an antique radio swapmeet, of all places, when I spotted a Macintosh 512K in its carrying case. It had a badge on the front reading "HyperDrive", which I hadn't seen before. There were no disks in the carrying case, but I figured I'd carry it to the test table to see if it powered up. Imagine my surprise when the expected disk '?' icon turned into a Happy Mac, followed by the HyperDrive splash screen! Turns out that it has an internal hard drive installed, which I'd never seen before in a pre-SE Mac. It apparently has System 1.1 (Finder 5.3) installed across three folders labeled "HyperDrive System Folder 1/2/3", oddly enough. Here are some pictures:








    Unfortunately, shortly after I finished taking these photos, I heard a series of crackling and popping noises from inside the case, followed by smoke rising from the ventilation slots! The unit was turned off at the time, so I'm guessing it was a 'safety capacitor' in one of the power supplies (it apparently uses a separate supply for the internal hard drive). Hopefully, there's enough of it left to read the component value off of, and hopefully I can find a replacement part without too much issue (haven't seen proper X/Y-rated capacitors at my local electronics suppliers, best I can tell). Pyrotechnics aside, I think I did pretty well for $60.
    -Adam
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  2. #2

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    It's fairly rare. It's a coveted upgrade for many 128k and 512k owners. A working one is pretty rare. Either the HDD dies from stiction or the power supply goes. The reason it's sought after is because you can have a relatively fast mass storage device on 128k or 512k without swapping the ROMs out for a Plus. It was one of the first (if not the first) internal fast mass storage solution for the original Macintosh. The original Macintosh and its successor, the 512k, didn't natively support SCSI or indeed any attached fast storage device, and up until the Hyperdrive was released, the only options for mass storage were serial based. Serial drives by comparison were very, very slow and often still required you to boot off a floppy disk first, then restart to boot off the serial drive.

    The Hyperdrive by comparison was really fast as it used SCSI. Not only was it fast, but it was also an internal solution. You didn't have to give up desk real estate for bulky external drives. It was very innovative for its time. If I remember correctly, GCC developed their own SCSI implementation that Apple eventually licensed or purchased for use with the Macintosh Plus.

    http://macintoshgarden.org/apps/gcc-...ftware-drivers

    I actually have a boxed Hyperdrive installation kit. I uploaded the software and most of the dealer installation manual (it was missing many pages, but the important pages were there.) It might be useful for troubleshooting or reassembling it.

    I'd recommend recapping the analog board and the power supply for the Hyperdrive. The Hyperdrive has its own dedicated power supply.

  3. #3
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    Installation for these things is a real nightmare. Bolting a 3.5" drive and another AC power supply in the confine of the compact case about an inch from the CRT neck and running all the wires and ribbon cable is a real bear. The Miniscribe drive they spec'ed out for this is generally unreliable, so finding one in working condition is quite a feat.

  4. #4

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    Quote Originally Posted by olePigeon View Post
    It's fairly rare. It's a coveted upgrade for many 128k and 512k owners. A working one is pretty rare. Either the HDD dies from stiction or the power supply goes. The reason it's sought after is because you can have a relatively fast mass storage device on 128k or 512k without swapping the ROMs out for a Plus. It was one of the first (if not the first) internal fast mass storage solution for the original Macintosh. The original Macintosh and its successor, the 512k, didn't natively support SCSI or indeed any attached fast storage device, and up until the Hyperdrive was released, the only options for mass storage were serial based. Serial drives by comparison were very, very slow and often still required you to boot off a floppy disk first, then restart to boot off the serial drive.

    The Hyperdrive by comparison was really fast as it used SCSI. Not only was it fast, but it was also an internal solution. You didn't have to give up desk real estate for bulky external drives. It was very innovative for its time. If I remember correctly, GCC developed their own SCSI implementation that Apple eventually licensed or purchased for use with the Macintosh Plus.

    http://macintoshgarden.org/apps/gcc-...ftware-drivers

    I actually have a boxed Hyperdrive installation kit. I uploaded the software and most of the dealer installation manual (it was missing many pages, but the important pages were there.) It might be useful for troubleshooting or reassembling it.

    I'd recommend recapping the analog board and the power supply for the Hyperdrive. The Hyperdrive has its own dedicated power supply.
    Thanks for the reply! I figured these sorts of upgrades weren't terribly common; before I found this 512K, I was only vaguely aware of its existence. I'm rather amazed that it worked on the first try; my experience with 3.5" MFM hard drives has been rather poor, particularly with regards to the 20MB MiniScribe HD used in my Sun Remarketing-modified Apple Lisa 2. I'm not sure who made the hard drive used with this mod; the only marking I could find, on the defect sticker, looks like two 'M's stacked one atop another, with a lower-case 'i' to the right of them (it's hard to see due to the small amount of clearance between the top of the drive and the mounting bracket). Trying to search for "MMI hard drive" on Google brings up loads of info on Audi car audio systems, so I'm rather stumped at the moment. Anyway, here are some pictures of what I found when I cracked open the 512K's case:


    Side view. You can see the hard drive with its mounting bracket, the line filter installed on top of the floppy drive (with ferrite beads), and the thin cable going to the cooling fan. The HyperDrive power supply is between the floppy drive cage and the analog board.


    Corner view, for good measure. Rather cramped fit in there.


    The wires which run power to the HyperDrive's power supply. Also, you can see collateral damage from the blown safety capacitor.


    The culprit. Capacitor C38 on the 630-0102 (820-0082D) analog board. Have yet to track down the service manual to figure out the value of the part, and most of the case has been obliterated. Appears to be Y-rated, at the least.


    A view of the cooling fan, for good measure. Not sure off-hand what the purpose of the box between it and the power cable is supposed to be. Some sort of temperature sensor?

    Very cool that you have a boxed kit! How were these installed? Did you have to bring the Mac to a HyperDrive dealer, or could you opt to do it yourself if technically proficient? By the way, according to Wikipedia, the General Computer Company (Corporation?) had a hand in both Ms. Pac Man and the Atari 7800. As a collector of vintage video games, I find it fascinating that they moved into the computer accessory market afterwards, and created the HyperDrive.
    -Adam

  5. #5

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    Quote Originally Posted by dorkbert View Post
    Installation for these things is a real nightmare. Bolting a 3.5" drive and another AC power supply in the confine of the compact case about an inch from the CRT neck and running all the wires and ribbon cable is a real bear. The Miniscribe drive they spec'ed out for this is generally unreliable, so finding one in working condition is quite a feat.
    Yeah, it definitely looks like it was a pain in the ass to cram all this stuff into the little case! However, it seems to have been done about as well as could've been expected for a hack of this magnitude, and the fit-and-finish seems to be reasonable overall. As I mentioned above, the hard drive does not appear to have been made by MiniScribe, or at least, I couldn't see their logo on what of the top plate I could see. The only marking I spotted resembled something like "MMi".
    -Adam

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    Quote Originally Posted by AdamAnt316 View Post

    The culprit. Capacitor C38 on the 630-0102 (820-0082D) analog board. Have yet to track down the service manual to figure out the value of the part, and most of the case has been obliterated. Appears to be Y-rated, at the least
    Get that battery out ASAP, you can see the connection has the stereotypical green corrosion. It's only a matter of time before the battery spills its guts all over the logic board.

    Clean out the battery compartment and use vinegar to neutralize the battery goo.

    The blown capacitor is an X capacitor, not a Y capacitor. Y caps are generally blue and cylindrical, which go from the circuit to ground. An X cap is placed across the load in parallel. Judging from its proximity from the mains plug, its probably part of the transient filtering stage and usually has a value between .22 and .33uF. X capacitors usually have built in resistors, and it looks like that might be what failed inside it since the top is blown off. If you take the cap out, you should be able to see the rating on the side of the capacitor.
    Last edited by GiGaBiTe; May 15th, 2018 at 12:18 AM.

  7. #7

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    Quote Originally Posted by GiGaBiTe View Post
    Get that battery out ASAP, you can see the connection has the stereotypical green corrosion. It's only a matter of time before the battery spills its guts all over the logic board.

    Clean out the battery compartment and use vinegar to neutralize the battery goo.

    The blown capacitor is an X capacitor, not a Y capacitor. Y caps are generally blue and cylindrical, which go from the circuit to ground. An X cap is placed across the load in parallel. Judging from its proximity from the mains plug, its probably part of the transient filtering stage and usually has a value between .22 and .33uF. X capacitors usually have built in resistors, and it looks like that might be what failed inside it since the top is blown off. If you take the cap out, you should be able to see the rating on the side of the capacitor.
    Thanks for the reply. I have indeed pried the battery out of its holder. Not nearly as much corrosion leakage as the Maxell 1/2-AA in my Mac Classic, so I think the computer will be OK. There's other areas of corrosion on the chassis (particularly the left side under the analog board, and on the left rear near the port shield) that are far from the PRAM battery socket; not sure what's up with that. Couldn't find an obvious source for said corrosion, and I'm pretty sure it didn't come from the battery. I'll clean up what of it I can, in any case.

    Thanks for pointing that out. I found a repair document which stated C38 as being a 0.1F capacitor, but didn't mention anything about an X- or Y-rating. I've seen pictures of blown-up capacitors of this style before, but this is the first time I've had one blow up on me in one of my own computers (did once have a 0.47F molded-paper capacitor blow up on me in an old tube radio, but said part was about 25 years older than this one, and not a safety-rated part). The sides of the C38 capacitor have also been blown apart, and you can see the soot residue on the large radial electrolytic capacitor across from it, so it went up rather violently.
    -Adam
    Last edited by AdamAnt316; May 15th, 2018 at 02:29 PM.

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    Quote Originally Posted by AdamAnt316 View Post
    Thanks for the reply. I have indeed pried the battery out of its holder. Not nearly as much corrosion leakage as the Maxell 1/2-AA in my Mac Classic, so I think the computer will be OK. There's other areas of corrosion on the chassis (particularly the left side under the analog board, and on the left rear near the port shield) that are far from the PRAM battery socket; not sure what's up with that. Couldn't find an obvious source for said corrosion, and I'm pretty sure it didn't come from the battery. I'll clean up what of it I can, in any case.
    Someone could have spilled something on it at some point, old crackerbox macs tended to be abused once their useful lifespan was over and they went into storage.

    Quote Originally Posted by AdamAnt316 View Post
    Thanks for pointing that out. I found a repair document which stated C38 as being a 0.1F capacitor, but didn't mention anything about an X- or Y-rating. I've seen pictures of blown-up capacitors of this style before, but this is the first time I've had one blow up on me in one of my own computers
    A bit of brief research had people saying that the epoxy potting used tended to break down over time from the hot box nature of crackerbox macs having nearly zero ventilation. The other capacitors on the board are suspect as well.

    Quote Originally Posted by AdamAnt316 View Post
    (did once have a 0.47F molded-paper capacitor blow up on me in an old tube radio, but said part was about 25 years older than this one, and not a safety-rated part).
    Hopefully you recapped the entire radio. Old wax and paper capacitors in even the newest tube radios from the late 60s and early 70s are long since expired. The paper starts to go acidic and causes the capacitors to leak electrically. The electrically leaky caps start passing DC current through them and can red plate tubes, drive them really hard and burn out transformers. If the radio was stored in a hot environment, the allen-bradly style brown resistors commonly used can also fail from internal breakdown that causes internal arcing.

    Just be careful inside those old tube radios, they're even more dangerous than a CRT. Pretty much everything can be high voltage DC in the range of 300-500 volts.

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    Steel-and glass Sprague "Vitamin Q" capacitors can fail in very spectacular and dangerous ways. I narrowly avoided having one embed itself in my ugly puss. Instead, it embedded itself in the ceiling tile seconds after I moved away to grab a meter.

    Probably why they don't make them any more.

  10. #10

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    Quote Originally Posted by GiGaBiTe View Post
    Someone could have spilled something on it at some point, old crackerbox macs tended to be abused once their useful lifespan was over and they went into storage.
    Not entirely sure. I've seen corrosion like this on the chassis of other Macs; while some of it could be chalked up to battery leakage, that likely isn't the case with this one. I'll have to take some pictures of it next time I have the case open to show you what I mean.

    Quote Originally Posted by GiGaBiTe View Post
    A bit of brief research had people saying that the epoxy potting used tended to break down over time from the hot box nature of crackerbox macs having nearly zero ventilation. The other capacitors on the board are suspect as well.
    According to this forum post, these old RIFA safety capacitors don't have a very good reputation in general. The resin shrinks over time, causing the case to crack, letting moisture in which leads to failure. Even NOS examples show signs of impending doom. As for the rest of the capacitors, I will look into replacing them. None of the ones I could see had swollen tops, but I know it's only a matter of time with electrolytic capacitors this old.

    Quote Originally Posted by GiGaBiTe View Post
    Hopefully you recapped the entire radio. Old wax and paper capacitors in even the newest tube radios from the late 60s and early 70s are long since expired. The paper starts to go acidic and causes the capacitors to leak electrically. The electrically leaky caps start passing DC current through them and can red plate tubes, drive them really hard and burn out transformers. If the radio was stored in a hot environment, the allen-bradly style brown resistors commonly used can also fail from internal breakdown that causes internal arcing.

    Just be careful inside those old tube radios, they're even more dangerous than a CRT. Pretty much everything can be high voltage DC in the range of 300-500 volts.
    It's currently on the 'to-do' pile. The radio in question was an AC/battery portable, namely a Zenith TransOceanic. Highest voltage seen by the circuitry (apart from the input of the AC power supply) is somewhere around 90 volts. I generally ran it on a homebrew battery pack (six D-cells for filaments/A+, ten 9V batteries for plate/B+), and it actually worked fairly well in spite of still being equipped with 1950s/1960s parts. Only issues I had with it were fading when operated on AC power (likely due to a bad selenium rectifier), and the failure of the filament in one of the tubes (3V4). Other than that, it worked pretty well for a number of years.

    I'm aware of the dangers of working on tube equipment. Fortunately, I haven't gotten any particularly nasty shocks from the gear I've worked on as of yet ***KNOCK ON WOOD***. I do my best to respect these sets, and keep one hand in my pocket if I think I might come into contact with the high voltage section.

    Quote Originally Posted by Chuck(G) View Post
    Steel-and glass Sprague "Vitamin Q" capacitors can fail in very spectacular and dangerous ways. I narrowly avoided having one embed itself in my ugly puss. Instead, it embedded itself in the ceiling tile seconds after I moved away to grab a meter.

    Probably why they don't make them any more.
    Yikes! How the hell did that happen?! I've never heard of a Vitamin Q capacitor exploding in that fashion. Generally, they're considered quite reliable, and paper-in-oil capacitors are sought-after by audio nuts. Of course, that's not always the case; Japanese paper-in-oil capacitors as used in early tube hi-fi equipment like the Sansui AU-70 are generally referred to as being akin to firecrackers, and even the 'bathtub' capacitors used in old military radio gear have been known to spring leaks, both in the electrical and literal senses.
    -Adam

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