Genesis overclocking problem: What am I doing wrong?

[wavel]

Hello to all!

I am trying to overclock my Sega Genesis, from the Epicenter schematic and plans. I have managed to successfully incorporate the halt switch and switch between the two onboard frequencies present on the stock machine. However, that speed is unstable, so I would like to run slower.

I purchased several metal can oscillators, 5v, including one specifically listed in David Howland's Genesis mod guide. 9.216 mhz, 10 mhz, and 12 mhz. However, when I feed the clock output into the 68000 clock input (the same pin I feed the onboard 13+ mhz signal), it doesn't work..with any of them.

Can someone who has successfully incorporated a different oscillator into a Genesis show me where I've gone wrong? I notice that the original 7.62mhz signal does not trace straight to the CPU. There is no continuity on a powered down board between the osc clk out and the cpu clk in pin.

I've checked my supply voltage (I'm running off the back of the 5V supply to the old osc), and ground. I don't have an oscilloscope, so the only thing I can't check is the clock output, but I can't believe that three different cans would be bad.


Am I connecting an external clock to the right point?

[flax]

I'm interested in a solution to this as well. I couldn't get a "external" oscillator either, went with the otherone on the motherboard, but as you say, it isn't stable. Think I fried the one I tried with first though. It didn't work so I thought that I had connected it wron, hooked up the un-regulated 10Vish power to it, burned my finger on it