Recent content by RetroViator

Charlie is Copacetic Charlie was working well after the recap, except it would not properly shutdown with Caymac's Power Up IIusi replacement PSU. I followed the power signal on the PSU's pin 9 (J15) back to the Egret chip, a 68HC05, at UB1. The connection seemed good, so the issue was either...

Bravo is Beautiful Bravo is the system I've worked on the longest (technically, I started working on it in 2021), and it is finally good to go. It's last problem was bad serial communication. TechStep was reporting a Serial Communication Controller test failure. Most specifically, it said...

Alpha is A-Okay After spending time on Bravo's audio problems, I decided to check out Alpha's speaker problem while the subject was still fresh in my mind. Alpha was working perfectly after I restored it back in 2021, but I was using it as a known-good system for testing, and along the way, my...

Back to Bravo Bravo finally has a voice. I went back to consider the odd oscilloscope readings I saw earlier, and I started at the beginning with the power going into the Sony sound ICs. Both were getting 4V. At first I wasn't sure what voltage they should be receiving, but I knew 4V seemed...

I suggest getting an extension cable with individual cables (like the one I have in the photo), and then use a hack saw to cut off the first ten pins that align with the Mac's power input jack. Be sure to check the orientation so you get the right pin alignments.

Yes, an 24-pin ATX power supply cable can be cut down as an extender for several ‘90s Mac PSUs. Here is one connected to a Mac IIsi.

What's next... I tested each of the five functional boards with my snazzy TechStep built by @max1zzz. It confirmed that Delta and Echo are working perfectly. Charlie tested fine, but it would not shut down with the new Power-Up-IIusi PSU (it works properly with the Magnetek PSU) . It was the...

The Dreaded Power Supplies Knowing how bad the IIsi power supplies are (due to leaky SMD caps on the soft power daughter board and leaky axial caps on the low voltage side of the main board), I decided to try the Power-Up-iiusi (Lucy) board that Caymac Vintage posted on Github. I realize he is...

Back in the day, I ran my college's computer store, and I dialed into AppleLink regularly to place orders, download product sheets, access software, etc. This was back when it was just an internal/dealer network. I have good memories of staying up late into the night to download system software...

I've worked with ex-military guys over the years, and while it seems a bit gimmicky at first, it really does clarify and simplify things. Sort of like using a 24 hour clock instead of AM/PM.

I've seen it eat one of those resistors, but it's impressive to see all three obliterated. 😬

What a mess. 😩 I’d be interested in a poll of what Mac or Mac peripheral has the worst corrosion or leakage problems. I’d have to think the IIsi PSU would be among the top contenders.

Hard Drive Archeology Tonight, I plugged in seven hard drives from the Mac IIsi to see if anything was salvageable. There were three Quantum LPS drives (two of which were 80MB and one was 230MB), a Quantum ELS of unknown size, a 40MB Conner drive, a 120MB Maxtor, and finally a 200MB Maxtor...

Tonight was floppy night I worked on all seven floppy drives, following @Branchus excellent restoration tutorial. It was like spending an evening with the Bob Ross of vintage Mac repairs. 🙂 I nearly stumbled on the eject gears. While disassembling the eject mechanisms, I noticed that two...

Logic Board Summary: I started with one working IIsi, and I now have five functional IIsi logic boards! Here is a run down: Alpha - Recapped and working in 2021, now has an audio issue * Bravo - Recapped and failed repair in 2021, now working except for an audio issue Charlie - Recapped and...