Apple II+

This Apple II+ was acquired from one of the computer history/museum message boards around November 2020. It was a pretty nice system:

  • Apple II+ working but video seemed corrupt
  • Apple Disk II x 2
  • Apple Monochrome composite monitor
  • Microsoft language card
  • Apple Super Serial card
  • TimeMaster card
  • Applied Engineering Viewmaster card
  • Disk Interface card
  • Microsoft Softcard

The machine was in fantastic shape when it arrived and everything looked fantastic. Taking a chance, I hooked it up to a power supply from another machine and tried it out to see if it would boot. The video was very scrambled, although it was somewhat better when I bypassed the Viewmaster card. At this point, I set the system aside for future service.

Coming back to this system last weekend (6/17/2022) I started working on it. I stripped everything down so I could check solders on the motherboard, particularly around the video. I didn’t find anything suspicious and later decided I have at least 1 bad RCA composite video cable.

I replaced the 0.1 uf RIFA capacitor in the power supply with a new one (100 nf that seemed to be a replacement X2 class for the original X class). BTW, if you’re disassembly the power supply from an Apple II series unit, for the wiring harness going through the strain relief, hold the power supply so you are looking at the end with the strain relief and its cutout should be up. It will be tight and you’ll need to watch your fingers and also the wires when you do the next part: firmly rotate the strain relief body 90 degrees clockwise (not counterclockwise as suggested by some videos). At approximately 90 degrees rotation you should be able to firmly rock the strain relief out of the frame towards you. Be very careful not to nick any wires.

Due to some cards that I already had available, I chose to install the following cards as I brought the system back online:

  • Slot 0: Microsoft Langauge (2022-06-21: Found Titan Accelerator IIe apparently causing problems with Disk II and 5.25″ Drive Controllers)
  • Slot 1: Apple Super Serial Card
  • Slot 2: Microsoft Softcard (2022-06-21: Installed, not yet tested)
  • Slot 3: Applied Engineering Viewmaster card (needs new cables)
  • Slot 4: Saturn 128k RAM card
  • Slot 5: Empty
  • Slot 6: 5.25″ Drive Controller card (2022-06-21: Working with 1 5.25″ A9M0107, need to switch back to Disk II controller and drives)
  • Slot 7: Empty

Next, testing the drives I found that neither one would boot or read a disk. So far I’ve disassembled one of them and found that it was pretty clean inside. However, there was a 74LS125 chip trapped between the housing and the floppy drive frame. Further inspection revealed it was damaged but wasn’t missing from the drive I was working on. After running the drive outside the case I’m nearly positive someone has plugged it into the drive controller incorrectly. I’ve ordered 10 74LS125 chips and will be replacing it in both drives as they both act exactly the same. [Note 2022-06-21: Likely these problems were caused by the Titan Accelerator IIe card]

Installed BOOTI card in Slot 7 on 2022-06-21. Within 10 seconds of power up, magic smoke was coming out the back of the Apple II+ chassis. Turned off power, found BOOTI card had 2 traces that had burned off varnish and a couple of discolored chips. Not going to try this again until I find out why this happened. Can’t find support email address to see if this has happened to other people. Not willing to trust in my oldest machine again, though.

Updates will follow. If you have questions about any of the info above let me know. I’ll be adding a few pictures as well, particularly of the RIFA safety capacitor. Turns out it was very badly cracked and I’m surprised it hadn’t already exploded.

ADTPro works fine for BootStrapping ProDOS and ADTPro Serial Client to the SSC in both slots #1 and 2. However, after that it will not work to allow DIR or RECEIVE on my MacBook. I’m using a legit cable so I don’t think it’s just a driver issue. Went ahead and switched to my IIe Platinum to do some additional testing 2022-06-21.