Zarquon

Hi Chas - thanks for the reply. My fault for not being clear! I'm after the Hitachi HD43517 IC's, rather than the CPU. I tried swapping the 2 chips over to check if the "good" one would work in the "upper octave keys" and vice versa - it is a bad chip, very distorted (quite nice sounding tbh, but I can get that with a fuzzbox!). Just wondering if they were used in any other keyboards that weren't Casio or maybe early computer boards etc?

New joiner here! Any ideas where these chips can be sourced, apart from the usual places (ebay/spares repairs etc)? I have a casio 1000P, with a distorted output on one of the IC sound chips (desoldered and swapped them over...), the other is fine. Are they all compatible - 601 /701 /MT-70 etc? thankyou