20MHz Daystar Turbo 040i Speedup
The Daystar Turbo 040i 20MHz card in a Mac IIsi can be clock chipped to roughly 40MHz with virtually no loss in stability. A few pointers from Brad Wilson (email@example.com) are included below with regards to the modification.
- The original crystal oscillator on the card is a 10MHz full size metal can which gives a 20MHz card.
- This is the board without the FPU, but it probably makes no difference.
- Initially the Mac IIsi itself was not clock chipped.
- Later the Mac IIsi was clock chipped, and there was a speedup in the video.
- Replacing the oscillator with a 4 pin IC socket enabled an easy testing platform where different oscillators could be tested. Be careful when removing the original crystal oscillator as the card is a multi-layer PCB and Daystar did a great job in soldering the crystal onto the board. An industrial-grade desoldering station with vacuum pump can be very handy.
- Install a heatsink on the 68LC040.
- If you have extra heatsinks you may want to install them on some of the other smaller components on the board; they get pretty warm.
The latest version of the Turbo 040 software is QuadControl Cdev v2.3
- With a 12MHz oscillator (24MHz) the machine was rock solid.
- With a 14MHz oscillator (28MHz) the machine was rock solid.
- With a 20MHz oscillator (40MHz) the machine was rock solid.
- This is as fast as he tried.
If you have any questions feel free to contact Brad Wilson (firstname.lastname@example.org)