Hey,
I've removed the data corder and all that's left is a separate pcb connected to the power switch
It's kind of big. Is it possible to do away with this and replace with a much smaller circuit?
(and retain the speaker and sound generation of the original PCB)
If there was a schematic for this PCB maybe could copy it just without the tape stuff?
Did you check the schematics page on the WIki?
https://www.cpcwiki.eu/index.php/Schematics => CPC classic => Disc and cassette schematics
On the connector to the tape deck, the top pin and the third pin need to be bridged to start the computer. You can run any switch you like (that can take a 3A switching current) to those pins.
Bryce.