Uploaded August 2025 | Updated September 2026, 1 week ago
The Macintosh IIsi was launched as a lower-cost alternative in the Macintosh II series. To keep costs down, Apple used more electrolytic capacitors, and the surface-mount electrolytic capacitors from the early 90s are past their expected lifetime. In addition, despite the power supply being made by Sony, the capacitors in it are also known to leak (though I can't help think "cost tweaking" by Apple led Sony to use lower grade capacitors).
And there lies the crux of the problem I'm facing: the power supply is currently irreparable. Specifically, the daughterboard in the power supply has too much corrosion to repair, and needs to be replaced. Folks are working on a replica PCB for this daughterboard, so I'm not going to scrap the original parts just yet. But I would like to be able to continue troubleshooting the logic board, which is going to require something more than a Iici power supply*...
That's why I ordered some PCBs from a major PCB manufacturer (they're not sponsoring the project or stream, so I am going to decline to name them). This PCB should allow me to mount an AC to 12VDC power supply and a PicoPSU inside the original IIsi power supply case. I won't have all of the parts, but I have enough to then use a standard ATX power supply for testing.
Will the power adapter board work? Will the IIsi "just work"? Or will I find more work to do? You'll have to watch to find out!
* The IIsi and Iici power supplies are electrically compatible, but not physically compatible: Apple turned the power connector 180°. Not that they were physically compatible size wise to begin with, but the connector rotation makes using a Iici power supply on a IIsi just a bit awkward...
*
Table of Contents
0:00:00 Pre-Roll
0:02:39 Greetings and Announcements
0:04:42 Things You All Have Sent Me: Stickers from @JamiesHackShack
0:09:24 Wheel of Regrets™ (Who comes up with these titles anyway?)
0:10:02 Wheel of Regrets™: Kouwell KW-557B Super ISA Bus Multi I/O Card
0:14:20 Wheel of Regrets™: Soyo SY-012 386DX Motherboard with 8MB of DIP RAM
0:28:36 Wheel of Regrets™: Pentium Pro Industrial Single Board Computer
0:36:45 Wheel of Regrets™: Three Corsair 1GB DDR2 Memory Modules
0:39:20 Wheel of Regrets™: the SE-style keyboard and tank-style mouse that were supposed to be included with the Performa 600
0:44:54 Building a Power-Up-iiusi to Adapt a Desktop ATX Power Supply to the IIsi
1:56:26 Smoke Test of the Power-Up-llusi and Continued Troubleshooting of the Macintosh IIsi (number 1)
3:56:16 Closing Thoughts
4:06:19 Outro
Links for Following Along:
Power-Up-llusi: github.com/brporter/iisi-pcb-replacement
(I used the Gerber files from this repo; order from your favorite PCB manufacturer.)
Note: Several people are working on a "reloaded" boards for the original IIsi power supply components. Those PCBs were not ready in time for trying them during this livestream. Therefore I used the only option available for rebuilding a IIsi power supply.
*
Ways to Support the Channel:
☕️ Tips or Support via Ko-fi: ko-fi.com/jdmcs
🈷️ Support me on Patreon: patreon.com/jdmcs
📦 Amazon Wishlist: jdmcs.net/wishlist
... or simply do the YouTube things: Like/Dislike, Comment, Subscribe, Enable Notifications, and participate in the Chat. These things help the channel, too!
**
Read Computerized Start™, my Official Blog: jdmcs.net/myblog
Follow me on Instagram: jdmcs.net/myinstagram
Follow me on Twitter: jdmcs.net/mytwitter
The Macintosh IIsi was launched as a lower-cost alternative in the Macintosh II series. To keep costs down, Apple used more electrolytic capacitors, and the surface-mount electrolytic capacitors from the early 90s are past their expected lifetime. In addition, despite the power supply being made by Sony, the capacitors in it are also known to leak (though I can't help think "cost tweaking" by Apple led Sony to use lower grade capacitors).
And there lies the crux of the problem I'm facing: the power supply is currently irreparable. Specifically, the daughterboard in the power supply has too much corrosion to repair, and needs to be replaced. Folks are working on a replica PCB for this daughterboard, so I'm not going to scrap the original parts just yet. But I would like to be able to continue troubleshooting the logic board, which is going to require something more than a Iici power supply*...
That's why I ordered some PCBs from a major PCB manufacturer (they're not sponsoring the project or stream, so I am going to decline to name them). This PCB should allow me to mount an AC to 12VDC power supply and a PicoPSU inside the original IIsi power supply case. I won't have all of the parts, but I have enough to then use a standard ATX power supply for testing.
Will the power adapter board work? Will the IIsi "just work"? Or will I find more work to do? You'll have to watch to find out!
* The IIsi and Iici power supplies are electrically compatible, but not physically compatible: Apple turned the power connector 180°. Not that they were physically compatible size wise to begin with, but the connector rotation makes using a Iici power supply on a IIsi just a bit awkward...
*
Table of Contents
0:00:00 Pre-Roll
0:02:39 Greetings and Announcements
0:04:42 Things You All Have Sent Me: Stickers from @JamiesHackShack
0:09:24 Wheel of Regrets™ (Who comes up with these titles anyway?)
0:10:02 Wheel of Regrets™: Kouwell KW-557B Super ISA Bus Multi I/O Card
0:14:20 Wheel of Regrets™: Soyo SY-012 386DX Motherboard with 8MB of DIP RAM
0:28:36 Wheel of Regrets™: Pentium Pro Industrial Single Board Computer
0:36:45 Wheel of Regrets™: Three Corsair 1GB DDR2 Memory Modules
0:39:20 Wheel of Regrets™: the SE-style keyboard and tank-style mouse that were supposed to be included with the Performa 600
0:44:54 Building a Power-Up-iiusi to Adapt a Desktop ATX Power Supply to the IIsi
1:56:26 Smoke Test of the Power-Up-llusi and Continued Troubleshooting of the Macintosh IIsi (number 1)
3:56:16 Closing Thoughts
4:06:19 Outro
Links for Following Along:
Power-Up-llusi: github.com/brporter/iisi-pcb-replacement
(I used the Gerber files from this repo; order from your favorite PCB manufacturer.)
Note: Several people are working on a "reloaded" boards for the original IIsi power supply components. Those PCBs were not ready in time for trying them during this livestream. Therefore I used the only option available for rebuilding a IIsi power supply.
*
Ways to Support the Channel:
☕️ Tips or Support via Ko-fi: ko-fi.com/jdmcs
🈷️ Support me on Patreon: patreon.com/jdmcs
📦 Amazon Wishlist: jdmcs.net/wishlist
... or simply do the YouTube things: Like/Dislike, Comment, Subscribe, Enable Notifications, and participate in the Chat. These things help the channel, too!
**
Read Computerized Start™, my Official Blog: jdmcs.net/myblog
Follow me on Instagram: jdmcs.net/myinstagram
Follow me on Twitter: jdmcs.net/mytwitter
![COMPUTER Repair: Three Rows of Sockets To Go In My MCA Apple ][+ Clone (Computerized Start™ Live)](https://i.ytimg.com/vi/LEtutHlUnMs/mqdefault.jpg "COMPUTER Repair: Three Rows of Sockets To Go In My MCA Apple ][+ Clone (Computerized Start™ Live)
If COMPUTER, my MCA Apple ][+ Clone, could sing, it might be singing:
Desolder me down (Repair)
You desolder me, you desolder me
Or something like that...
Theres three rows of bad sockets left in COMPUTER, so the project to replace all the original sockets is in the home stretch. With each new row of sockets, both the appearance of the motherboard and my confidence in a fully-working COMPUTER increases. Maybe tonights the night.
Will I get the remaining sockets replaced tonight? Will I be able to test the board? Will I find a mistake the had way? Youll have to watch to find out!
*
Use discount code JUSTINTIME for for 5% off all Computerized Start™ merchandise at https://shop.jdmcs.com.
*
Ways to Support the Channel:
☕️ Tips or Support via Ko-fi: https://ko-fi.com/jdmcs
🈷️ Support me on Patreon: https://www.patreon.com/jdmcs
📦 Amazon Wishlist: https://jdmcs.net/wishlist
... or simply do the YouTube things: Like/Dislike, Comment, Subscribe, Enable Notifications, and participate in the Chat. These things help the channel, too!
**
Read Computerized Start™, my Official Blog: https://jdmcs.net/myblog
Follow me on Instagram: https://jdmcs.net/myinstagram
Follow me on Twitter: https://jdmcs.net/mytwitter")
