Mac Plus and HD20

Hi everyone. First post here. This seems like the most active vintage Apple forum, aside from perhaps r/VintageApple.

I have recently gotten my hands on a Macintosh Plus and an HD20 (not the HD20SC, though). It's my first foray into vintage Apple stuff. The Plus was upgraded to 4 MB of RAM before I had it. I cleaned out as much dust as possible from both, and I cleaned and re-lubricated the floppy drive following Adrian's Digital Basement's tutorial. It and the hard disk work perfectly, as far as I can tell.

Unfortunately, the computer had no keyboard or mouse. The person I got it from---technically, it's not mine to keep, but nobody else wants it---included an ADB keyboard and mouse, sadly. I made a mouse from a PS/2 to Atari ST adapter from eBay (rewired into another DB-9 connector), and a keyboard from an Arduino with key input from my computer. I bought some floppies and made a serial cable, and with the help of a Performa 5260 I was able to borrow, I made System 6.0.8 disks. I have since installed that System on the hard disk and several tools, most notably of all THINK C 5.0, and I've been putting my C knowledge to use. It's a lot of fun.

I have a few questions, though. The computer came with a Fanny Mac accessory, a fan that sits in the handle of the computer and also acts as a power passthrough. In the interest of using it around other people, I typically use the Mac without the fan because it's very loud, but I run it for only a few hours at a time. I know that this is rather hazardous for the circuitry. How long is it safe to run a fully upgraded Mac Plus without a fan?

The other question I have is about the hard disk. It is almost concerningly loud. I cleaned out the fan from the dust that had accumulated on the blades, and I tested it. The fan in the drive is very quiet, maybe 40 dB if I had to guess. The noise, obviously, must come from the disk itself. Is this normal? How loud should the disk be?

I specifically no longer use my two Macintosh Plus as I have been unable to track down a FannyMac / System Saver. The Plus ran too hot when it was released and with 4mb of ram running it without a fan is going to crack those 30 year old solder joints.

for the hard drive unfortunately could be on its last legs. If it sounds like it’s grinding more than searching it’s in bad shape.

I personally wouldn’t run my Mac Plus any longer than perhaps 15 minutes without a fan. Definitely want to keep that flyback transformer somewhat cool. Definitely less replacements available now as they wear out.

For your FannyMac, guessing that is like the System Saver (what I have). Mine definitely makes noise but isn’t obnoxious. That said, if the noise level is too high can you swap out the fan component with something more modern?

As for the old hard drive, yeah those 1980s drives are loud in general. I’d say being able to hear it spinning when walking into a room is to be expected. That said, make sure you are backing up copies of any of your coding projects, I would put no trust in it to work the next day. Definitely keep using it until it dies, but don’t let it contain the only copy of any coding projects.

The Fanny Mac is loud, but it's not that big of a deal. I was more concerned about the hard disk, but from what the two of you have said, it's not an issue. I can definitely hear it within the room, and it doesn't make a grinding sound---it's more like a constant whir. I do make backups too, because duh, ha ha.

Would it also be worth recapping? It seems like a good idea, given its age, but I don't know.

Pluses aren't anywhere near as fragile as people think they are—they've lasted this long, after all, usually with abuse—but the PSUs are weaker than they should be. It won't be the end of the world to run it without a fan, it's very unlikely to spontaneously combust or anything—but it will shorten the life of bits of the machine. To what extent this really matters given how common pluses and plus spares are at this stage is up for debate. I err on the side of being reasonably careful; some other people do not. No matter what you do people will think you're being silly, so you'll really have to do your own risk analysis here.

Recapping the logic board on those things isn't really necessary; recapping the analogue board, on the other hand, is a good idea, preferably with capacitors all with 105 degree temperature ratings (the originals are often rated 85 degrees, and this was a misdesign). Another good idea which was popular around the time of release is to replace a number of the diodes with the next size/rating up. I think the details of which ones are in the 'mac plus logic board' PDF that's floating around.

The component to be really careful of is the small thyristor/SCR on the analogue board, I think it's Q11 on the US board.These are harder to find than flybacks, and much much easier to damage, and as far as I can see nobody's found a modern replacement that functions reliably.

And yes, the HD20 is pretty loud. If it sounds fairly smooth, rather than grinding, you're probably OK, but I'll defer to people who know more about it.

Old hard drives are loud; but depending on what sort o condition it is in; the sound it is making may mean it is on its way out. The thing that often kills the old drives is when they are powered up after sitting still for a long time.

As has been mentioned, running a Plus with no cooling won't immediately kill it, but it will also shorten its life - but it does depend on how long you're intending to run it for each day. The odd hour or two here and there with no cooling won't make much difference in my opinion.

I ran my Plus in the early 2000s all the time for a few hours. Still used it on and off these past few years, and it has now been recapped. Never had an issue at all.

Here's the bit I was thinking about:

"Other upgrades to improve reliability include a change in (nonpolar electrolytic) C1 to a 50V or 100V unit (from 35V), and changing 3A rectifiers CR1 and CR5 (GI854, equivalent to Motorola MR854) to 5A units. For the latter, Motorola part number MR824 seems to have been a popular choice."

(see https://vintageapple.org/gamba2/images/plus_analog.PDF, bottom of page 2)

cheesestraws said:

Here's the bit I was thinking about:

"Other upgrades to improve reliability include a change in (nonpolar electrolytic) C1 to a 50V or 100V unit (from 35V), and changing 3A rectifiers CR1 and CR5 (GI854, equivalent to Motorola MR854) to 5A units. For the latter, Motorola part number MR824 seems to have been a popular choice."

(see https://vintageapple.org/gamba2/images/plus_analog.PDF, bottom of page 2)

Click to expand...

Interesting reference, I hadn't see this before. I wonder if it has any merit?

I recently aquired a Mac Plus with a fan mod installed. They had cut a hole in the back and mounted the fan directly to the case, and then taped off a bunch of the air vents in order to force the air flow through a certain path. It works very well!

Stephen said:

Interesting reference, I hadn't see this before. I wonder if it has any merit?

Click to expand...

I only have anecdata: I have had failed semiconductors, probably due to heat. I replaced them with the next "grade" up and they have not failed again, though realistically that is more likely to be because they are new, rather than because they are more heat-resistant. Difficult to tell whether in the long term it will mean anything much.

I'm assuming the person who knew the AB well enough to write that document was probably better informed than I am, but that may be being more charitable than rational .

Thank you all. This is fun stuff, what can I say. I was originally trying to code in assembly (I have experience with Z80 assembly so I thought I'd take a stab at 68k), but I was using the original MDS and it was painfully slow. Also, I quickly discovered that assembly isn't exactly the best language for developing on a brand-new-to-me system.

I read in the System 6 user's manual that the hard disk shouldn't be turned on and off a lot because it can wear out the disk, and that it is better for the disk to leave it running unless you're going to be away from it for many hours. How much of a risk is this really?

I probably sound kind of paranoid, but I'm actually more curious than worried. I just wish I knew how much this system was used before I got it---I can definitely see menu burn-in on the CRT when it's off, for example.

Yes, writing assembly using the MDS as one's introduction to Mac programming sounds like an excellent way to tear one's hair out.

Certainly it is true that turning on and off new hard discs is the most stressful thing to do to them; what I don't know is whether this holds true after many years where other components might also be marginal.

The way I personally think of this, for what little it is worth, is that Pluses and Plus parts aren't at all rare or endangered at this point. They are also very repairable. So, while a little caution is sensible, don't forget that the only truly wasted computer is one that isn't being used at all. It's like preserved railway engines or cars: yes, they can look very pretty on pedestals all polished up, but these are things that were designed to go and be used, and it always feels (at least to me) like kind of a shame to stop them from doing what they were meant to do.

Very interesting perspective, cheesestraws. The vast majority of my machines are indeed "in the closet." I have roughly 3-4 out to be used at any time, mostly the same ones. That leaves almost 30 machines in the closet almost all the time. Most I have not yet gotten to fully repairing, and it will likely take me years to do so. However, once I do, and I don't use them, they stay there, in a humidity and temperature controlled, and dark environment for preservation. My goal is to have them last beyond me myself for the future. We all have a goal in mind, I suppose!

Yup. The only way to do this hobby wrong is to make yourself miserable by doing it . It'd be massively dull if we all did it in the same way.

My only complaint is when people hoard machines that they never intend to, or simply can't, fix, often just sitting there in a big pile to rot, or even exposed to the elements.

That is a whole other story. I cringe when I see the "finds" in a moldy warehouse, covered with soot. One guy I know found a pile of Apple IIs with a bees nest in them. Usually when I see some of these photos online, I just can't imagine what in the world happened to them.

Somewhere, there is a perfect balance between preservation and overuse. That said, these Macs seem shockingly reliable given their age and it's probably important to remember that.

Also, I always think it's unfortunate to hear someone instantly put down or abuse some retro piece of technology---how can you judge until you know the full story behind that thing, whatever it is?

I was also wondering about System 7(.5). I found a pre-made 500M disk image with 7.5.5 and I've been messing around in Mini vMac, but how would one go about installing it on a real Mac Plus? Clearly a hard disk larger than 20MB would be necessary, so I'm not planning to do it, but how would you get it on the disk in the first place? The disk images I can find are 1.4MB, obviously incompatible.

500MB would have been unthinkably huge at one point, but only moderately so by the time of 7.5 I think. As for transferring, you could (slowly) use appleshare, but you may want to use an intermediary mac with a large sd/scsi adapter to save time, if you have the materials.

What I've done in the past to get files transferred from a modern Mac to a 68K machine was to use a G3 or G4 minitower with a SCSI card and a 50-pin SCSI cable sticking out one of the back slots, along with a molex connector for power. Connect the bare drive to the two connectors, boot up the PowerMac, then transfer the files saved from the modern Mac to the 68K machine's drive. Once it's done, shut the PowerMac down, and reinstall the drive in the 68K machine (or an external SCSI case). Do whatever installation needs to be done on that machine. Later versions of DiskCopy can mount disk images, allowing installation of software without the need of a FDHD drive.

Another option is to use one of the USB zip drives and copy files from the modern Mac, then load them up on the 68K machine with a SCSI zip drive. That would nullify the need of an intermediate machine.

With respect to System 7.5.x, I've installed it on drives as small as 40MB. It'll run happily in that small of a space. Just have to strip out the excess junk that's installed. On a Plus or an SE, I'd probably do a custom install and prune it down to only what's necessary.

Strangely enough, I've never had a cooling fan on any of my pre-SE compact Macs. My original Mac (a PlatPlus 1/0 with dual floppy drives) had no issues running without one, even when I was playing Arkanoid and Super Tetris for hours on end. It'd feel warm after a long run, but never hot.

Keyboard-wise, the old DataDesk Mac101 keyboards can be used on either an ADB Mac or an earlier one that has the mini-RJ11 style keyboard cable, if you keep striking out on finding an actual Mac keyboard. An AppleMouse IIe or IIc is a direct replacement for the M0100 mouse used on the early Macs. Same connector, same shape and size. I actually use a M0100 with my Apple //e, since they are interchangeable.