Casio ZD-3 Service Manual page 30

4. Does not communicate. (Mecha mi-con does not start.)
Does not communicate.
Is system 5 V lines normal ?
Yes
Is system 3.3 V lines normal ?
Yes
Is RESET signal
normal ?
Yes
Can P-DOWN signal be
gotton ?
Yes
Does system rock oscillate?
Yes
Can signal be
gotton at communication
port?
Yes
* Mecha mi-con is defective.
No
No
No
No
No
No
28
* PS unit (set) or connector is defective.
* Check circuit around IC601.
* IC601 is defective.
* Check RESET circuit (set) or connector.
* RESET circuit (set) orconnector is defective.
* Check P-DOWN (set) or connector.
* P-DOWN (set) or connector is defective.
* Check oscillator.
* Oscillator is defective.
* Check communication line.
* Communication line is defective.