EPSON SG-615 Oszillator Speedup Clip

[franklyn]

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...

 

[franklyn]

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.

 

[Phipli]

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.

Making a Wombat Fast

Making 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.