68kMLA Classic Interface
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| EPSON SG-615 Oszillator Speedup Clip | |
| Posted by: franklyn on 2026-06-02 09:43:53 I’ve been tinkering a bit and am attempting to build a clip-on adapter for my Quadra 650 motherboard to overclock it to up to 40 MHz. I had tried this once before using homemade contact springs, but it didn't work due to contact issues with the SG-615 oscillator. I really don't want to solder directly onto the motherboard. I am now using parts cut from an ISA slot, which offers exactly the right pin pitch. All the individual pieces were cut from the slot—specifically using a Dremel or Proxxon tool fitted with a thin diamond cutting disc. So far, it looks promising. My plan is to solder a standard DIL-14 oscillator onto a small piece of perfboard mounted on top of the clip. If this works well, I might design a proper PCB to accommodate various 5-volt oscillator form factors. When the clip is seated over the SG-615 oscillator, all four contact points make a perfect connection. I simply need to connect GND, VCC, and the CLOCK output; additionally—specifically for the connection to the motherboard's SG-615 oscillator—I need to tie Pin 1 to GND to disable the onboard oscillator. I'm curious to see if it all actually works out... | |
| Posted by: franklyn on 2026-06-03 11:00:31 It works but my Quadra 650 Mainboard has some problems to run at 40Mhz. The Quadra boots up fine but the video output is corrupted, and the computer then freezes. | |
Posted by: Phipli on 2026-06-03 11:12:12It works but my Quadra 650 Mainboard has some problems to run at 40Mhz. The Quadra boots up fine but the video output is corrupted, and the computer then freezes. 
Making a Wombat FastMaking a Wombat Fast Or, how to bump your Centris 650, Quadra 650 or Quadra 800 to 40 MHz with minimal effort. A 40 MHz Quadra 650 (“Current System”) Traditionally, the way we have over…
elephantandchicken.co.uk
Tweak the timing resistors. There are 40MHz timings in the ROM. | |
| Posted by: franklyn on 2026-06-04 01:22:03 Thanks | |
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