Casio ZD-1 Service Manual page 25

4. No audio signal to output terminals.
4
Does audio signal
appear at pins 1 and 7
of IC707 ?
No
Does 4.23 MHz
appear at pin 11 (CLOK)
of IC702 ?
Yes
Does 88.2 kHz
appear at pin 42 (LRCK)
of IC702 ?
Yes
Does digital signal
appear at pin 9 (DATA)
of IC702 ?
Yes
* Check IC707.
* Check circuit around IC707.
Yes
No
No
No
* Check circuit around and soldering
IC702.
* Check IC702.
23
* Check Q901 and Q902.
* Check circuit around Q901 and Q902.