The Macintosh Plus - The Best Retro Macintosh?

The Macintosh Plus is one of my favorite retro computers in my collection.  It's understood that the first Macintosh has the most value, as does the first of anything, but in this case the Mac Plus is the last of the "original" Macs.  It's got the same industrial design (the same shape), and the early machines in the run have the same color as the originals.  These computer are significantly more useful, as they can have up to 4MB RAM, an external SCSI connector, and can run System 7.  Also, the double sided drive allows the system to read and write the original disks, but is also more practical should you want to run off floppies for nostalgia purposes, since you can have a boot disk and a program on the same disk.

The SCSI port is compatible with the SCSI2SD hard drive replacement,  I have two examples of the Mac Plus, a unit from 1986 and another from 1989, and they both work with SCSI2SD after using these settings.  From reading online, I believe that there were some special features added to the SCSI2SD to support these machines, but it's possible that early ROM versions of the Plus won't boot off SCSI2SD.  Personally, I've gotten Mac OS Version 4.1 up to 7.5.5 installed and booting off of 2GB partitions, but I didn't set up SCSI2SD to simulate a Mac drive, so I had to use Lido to get the drives setup.  I also have a FloppyEmu, which I normally use on the Apple IIs, but it's quite useful for bootstrapping these machines when it's time to install a new version of Mac OS, or load programs.

I've used both the SCSI2SD 5.5 in the external case, and most recently, I've transplanted a Version 5.1 device into the External SCSI enclosure shown above to simulate a somewhat more period correct look.  I documented that build in another article here.

My 1986 Mac Plus had been experiencing problems with overheating.  I recently brought it back onto the workbench, opened it up, and was able to replace a bad capacitor on the Power Supply board that had started to show signs of leakage.  I had not noticed this before during previous repairs, so I went carefully over the entire board.  I also ended up breaking off the fuse holder on the board, but that was a very inexpensive part from DigiKey.  While doing these repairs, I also installed a 12volt 60mm fan that I had on hand inside the case.  The machines’s been running much better now after a couple of day long burn in sessions, so I’m greatly relieved to have what is currently the oldest Mac in my collection working well again.

Macintosh Portable (1989) - Learning about a "New to Me" Computer

One of my recent acquisitions in the collection is an Apple Macintosh Portable.  This computer was released in 1989 by Apple, and was the first Portable computer (Battery powered computer) from Apple.  

At that point in time, I was interested in computers, but pretty unaware of what was going on in the industry, and certainly not aware of high-end business machines.  I've recently developed a strong interest in the 68K Macs and because of the high cost and low number of these machines that was produced, I never thought I'd be able to afford one.  I ended up getting this in exchange for labor helping someone clean out and price a large lot of retro computers.  I was a bit concerned because a fellow retro computing enthusiast told me that it took collecting three Portables before they were able to get a single working unit.   I was hopeful however because of the care that this collector had obviously taken.

My example is from 1990, near the middle of the run, this computer was not a big commercial success for Apple.  The cosmetic condition is excellent but from what I've learned online, since these were made during the early '90s capacitor plague, they all need a Recap.  The first videos I like to watch on a new computer that I'm unfamiliar with are from Jason's Macintosh Museum, here's one that shows how to open the computer.

At this point, I knew that I'd need a battery in order to start the Macintosh portable, thanks to some good advice, I was made aware of this solution for buying a new one online from this eBay seller, Alaska360.  While I was waiting for that part to come, I was able to dive in on the Recap.

Bruce from Branchus Creations has provided an excellent recapping guide here.  Bruce's guide is for the later Backlit model, M5126, and my unit is the first M5120 model, which I believe to be more common.  I used Bruce's guide as a starting point, and made edits to update it for the 5120.  I will include my edited version of Bruce's guide here.  Also, I'd highly recommend watching Bruce's video on the topic, he's got a high level of both knowledge and skill at repairing these machines.

I did my recap using parts from Digi-Key, which we are very fortunate to have right here in the state of Minnesota.  This went OK, but as it was my first time around the main challenge was that the Radial Caps I'd ordered had leads that were too thick to fit through the holes in the circuit board.  Here's my updated Bill of Materials for this,  I've updated the part number of the Radial Caps too 0.6mm leads instead of 0.8mm leads, although I haven't tested this yet.  Let me know via email or in the comments below if you have success with these caps with the smaller leads.

So, after the recap was complete and the battery arrived, it was time for the "Moment of Truth", the power up test.  I was super excited to see that the computer worked!

Getting to play around with this computer has been one of the major highlights of my year in retro computing.  The SCSI hard drive works, making it one of the few functioning SCSI drives that I have.  This SCSI drive has a proprietary connector, but if it does stop working the eBay seller I mentioned for the battery also has a special SCSI adapter that allows the Portable to run off SCSI2SD.  I expect this drive will die soon and that's an upgrade that will be on the near horizon for this machine.

There were a few problems with my portable.  First, I noticed there was no power up sound.  I suspected something was wrong with the sound circuit because I knew that during the recap several pads had lifted.  I did my best to repair that damage, but I've had trouble with the sound circuit on computers from this era before.  So, I started to search the forums, and again based on advice joined a "New to Me" forum for 68K macs, the 68KMLA forum.  This thread seemed to be on topic, so I joined in.  I got some really great advice, and I was able to resolve the issue!  I did have to take the entire computer back apart again to get at the board.

The second issue is more concerning, the display appears to be degrading.  If you look closely at the image,  you can see a line of about may 50 dead pixels at the top left corner, right along the line of the menu bar.  This was an image I took right after getting the machine running again.  Since then, another line has appeared along the right hand side.  I do not know yet if this screen is at repairable, it would be great if this was just a loose contact or something, but I don't anticipate that it will be repairable.  This is Apple's first Active Matrix screen, and I think it may simply be failing.   I'll keep my eyes out for a donor, and in the meantime, enjoy using the machine!

Apple II Plus - Trash to Treasure - Part II

In the last update, we left off with the Apple II Plus able to power on, but without testing either the keyboard or any of the hardware.  After the replacement keyboard cable arrived, I plugged the keyboard in for the first test.  Unfortunately, with the Keyboard plugged in I was getting repeated keystrokes over and over again.  I could tell that the Keyboard was working to some degree because when I'd press a key the correct key would come through, but then fill the screen with repeating characters till the next character was pressed.

I started troubleshooting by doing Google searches on the Internet.  My first understanding from what I'd read lead me to believe that the Keyboard Encoder board could have failed, which is a separate board that is attached too but not part of the keyboard on the Apple II and the II Plus.  I found this modern replacement for the Apple II Keyboard Encoder and ordered it.  The great thing about this solution is that it also includes a PS/2 port for attaching a modern keyboard. With this board and a modern keyboard you have a complete known good keyboard solution for the Apple II or the Plus.  After this arrive and I plugged it in, it had no effect, the problem persisted.

So, understanding that this problem was not with the Keyboard or the Keyboard Encoder board, this pushed me back to looking at and considering the motherboard.  I had read about the book "The Apple II Circuit Description", and so after my failure to properly diagnose the initial problem, I decided it was time to dig in and read this.  I read through the introductory parts of each chapter, and also dug in a bit on the Keyboard I/O schematic.  Feeling a bit unsure after the disappointment with the Encoder board, I decided it was time to reach out on the Vintage Computer Forums.  As has happened before, I received some great advice.  It ended up being one and only one bad 74xx Logic chip, replacing this with a new device solved the repeating key problem!

After testing the keyboard, I determined that four of the keys were not working, the previous cleaning had not been enough to rejuvenate them.  By using the Ohmmeter I was able to determine that the key switch contact was not closing.  Having repaired individual key switches before using a procedure demonstrated on Adrian's Digital Basement, I removed the problem keys by desoldering them from the keyboard, dis-assembling them, and carefully cleaning the switch plates.  These ended up being Alps short-step switches, so the mechanism was a bit unfamiliar.  I found that for some of the switches I had to spray contact cleaner in between the plates, then blow it out with compressed air a couple of times to clear the contact of whatever was preventing the circuit from closing.

After getting a complete working Keyboard, it was time too test the RAM.   I've attached my Disk Controller II card from my Apple IIe, and FloppyEmu to this system, but I did not have any success loading software onto this Apple II Plus, other than successfully loading DOS 3.3.   It turned out that part of my problem was not understanding how the DOS system worked, I needed to go back and read about that, too.  This simple list of DOS commands was helpful.  After I learned that this is a 48K Apple, and that because it's an Apple II Plus, it has Applesoft in ROM and not Integer Basic, then I started to understand why I could load certain programs and not others.

At this point, I was finally able to load and successfully run Apple-Cillin diagnostics on the machine.  Using this tool I was able to diagnose that the machine did indeed have some bad RAM.  By doing trial and error using the first bank of 16K of RAM, I was able to condemn four RAM chips and set aside another group of RAM chips that are working, but their legs are broken. Again, due to the fantastic Retro Computing community's online contributions, I learned that the electronics distributor Jameco still has the correct RAM chips in stock.  I ordered a bunch in order to replenish the top bank to bring this machine back to 48K, and have a few spares as well.

With either 32K or 48K, I can't run most of the Apple II software that's out there from my childhood because most of that requires a 64K machine, but I have the Apple IIe for that.  I think I'll try to outfit this machine to behave as an original Apple II.  Original Apple II prices have gotten a bit crazy, but I did find this cool modern card, a MultiROM card that allows the machine to load Integer Basic, or boot to the monitor and behave just like an original Apple II.  I put this on order, and with the the current situation with shipping during the Holidays, this project will go back on hold for a while.

Thanks for reading!  Let me know in the comments or in email what memories you have of the Apple II, II Plus, or IIe.  One of the things I'm currently researching is what people did with their Apple IIs with less than 64K RAM, what games were popular from the late seventies up till 1981 or '82?