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TROUBLESHOOTING
Nature of Trouble Faulty Block Checkpoint
No power Power IC (LA5668N) Pin 2 should have +9 V.
Power jack Jack contact.
No sound at all Power IC (LA5668N) Pin 6 should have +5 V.
Power amp (LA4127) Check output signals of pins 1 and 20.
Main clock generator Check oscillation at pin 105 of CPU.
CPU (CDT109-005) Pin 6 should receive a trigger pulse when
turning on the power switch.
Check signals DATA, BCLK, WCK1 and LRCK
of pins 107, 109, 111, and 112.
ROM (HN62414PD25) Check address/data bus.
Reset IC (S8053ALR) Pin 1 should provide a low level pulse when
the AC adapter is connected.
Key and switch matrix Open circuit on KO or KI line.
Key and switch matrix Dust on the con tact.
Distorted sound Power IC (LA5668N) Check voltages of pins 2 (+9 V) and 6 (+ 5 V).
ROM (HN62414PD25) Check address/data bus.
CPU (CDT109-005)
Certain keys or switches
do not function
A certain key or switch does
not function
Filter output: M5218APR-1 pin 1
B
Filter output: M5218APR-1 pin 7
Tone: Piano
Key: A3
C
C
B
Filter output: M5218APR-1 pin 1
D
Filter output: M5218APR-1 pin 7
Tone: Flute
Key: A3
E
E
D
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