Hi all, Hope this is in the right spot, it was initially a power supply problem, but does look might it might be a fried IC now.
I'm working on a Casio AZ-1 Keytar, i'll copy and past from another forum:
"...Against my better judgement, I'm trying to repair a Casio AZ-1 keytar.
Initial fault was not powering on (possibly had the wrong power supply plugged in at some point in the past) and T4 (a PNP transistor) had exploded.
After replacing, I was only getting around 2v where I should see 5v on the collector and the transistor gets hot quite quickly. Breaking the connection to the CPU IC (NEC D78C11G 030) pins 42 VAREF & 43 AVDD restores a stable 5v and T4 remains cool. Does this definitively point to a shorted CPU IC?
From what I can tell, the *11* version of this guy has custom firmware in the built in ROM, does anyone know where I might get my hands on it, assuming I could find a replacement IC with programmable ROM?"
Or, given that it's mask ROM, would that mean I specifically need to find the 030 variant of D78C11G?
Thanks for any pointers or advice!
(Service manual here:CASIO AZ-1 SERVICE MANUAL & PARTS LIST Pdf Download.)
I'm working on a Casio AZ-1 Keytar, i'll copy and past from another forum:
"...Against my better judgement, I'm trying to repair a Casio AZ-1 keytar.
Initial fault was not powering on (possibly had the wrong power supply plugged in at some point in the past) and T4 (a PNP transistor) had exploded.
After replacing, I was only getting around 2v where I should see 5v on the collector and the transistor gets hot quite quickly. Breaking the connection to the CPU IC (NEC D78C11G 030) pins 42 VAREF & 43 AVDD restores a stable 5v and T4 remains cool. Does this definitively point to a shorted CPU IC?
From what I can tell, the *11* version of this guy has custom firmware in the built in ROM, does anyone know where I might get my hands on it, assuming I could find a replacement IC with programmable ROM?"
Or, given that it's mask ROM, would that mean I specifically need to find the 030 variant of D78C11G?
Thanks for any pointers or advice!
(Service manual here:CASIO AZ-1 SERVICE MANUAL & PARTS LIST Pdf Download.)