Hi trag thanks for your input.

Interestingly, the Macintosh II, now that I've soldered in two new PRAM batteries, (this is an old one that had soldered PRAM batteries) is doing exactly the same thing as the Macintosh IIci. The PSU is firing up, the monitor is rasterising to a light/mid grey screen and then nothing.

The only conclusion I can come up with for both of them is they need new capacitors.

Thoughts?