Hi,

you have to check your oscillators if they are groundtone types or 3rd overtone (data sheet).

Overtone oscillators are much cheaper than groundtone ones, but they need a specific circuit to start in the right frequence. Modern hardware can use these types without problems.

The old chess computers do not have that specific circuit and are designed for oscillators < 25 mhz in most cases. You cannot change the basic circut easily and so high frequency oscillators will not run, if not in groundtone.

So I and others were looking for these special oscillators/resonators for a long time and are happy to find some. Only with these rare types tuning of old hardware makes sence. And there is no guarantee that it will work, it depends on the quality of the cpu/ram. E. g. we tried the same chess computers (Atlanta) and some work with 40 Mhz + high voltage, some only with 30 Mhz + high voltage, others with 36 Mhz and standard voltage - every item is a little bit different in the behaviour during overclocking.

Regards,
Achim