Troubleshooting - Sharp SM-SX100 Service Manual

• Power is not supplied.
Does AC100V stand between Pins 1 and 2 of the power
filter PWB connector CNP502?
Yes
Is AC100V supplied between the input L1/L2 of the
rectification unit UNT503?
Yes
Is any normal voltage is output from the power PWB
B1503/CNS503?
Yes
Is 5V supplied to Pin 13 of the microcomputer IC904?
Yes
Is any oscillating waveform found at Pins 14 (OSC2) and
15 (OSC1)?
• It neither sound at the analog nor digital input.
Are the speaker relays RLY108 and RLY107 switched?
Yes
Are they properly wired to the 1-bit amplifying unit?
(CNWAM1, CNWAM2, CNWAM3, CNWAM4)
Yes
Is voltage properly supplied to 1-bit amplifier? (CNP102)
Yes
Is voltage properly supplied to 1-bit amplifier? (CNP109)
Yes
Is any signal output from the connectors CNP107 and
CNP108 for 1-bit amplifier?
Yes
Check the inside of the 1-bit amplifying unit.

TROUBLESHOOTING

(LED does not come on and it does not sound.)
• Check the fuse F501.
• Check the parts on the power filter PWB.
No
• Check the wiring of the inlets SOC501 and CNS501.
• Check the wiring of the power switches SW501 and CNS502.
No
• Check whether CNS502 is wired across ST1 and ST2 of
No
the rectification unit or not.
• Check the output voltage (OYT terminal) of UNT501 and
UNT502.
• Check the parts (L504 to L511, F502, FS503 and R503 to
R506) on the power PWB.
• Check the 1-bit amplification unit.
(Try to disconnect CNWAM4 and CNWAM3.)
• Check IC107 output.
• Check R189.
No
• Check X901.
No
• Check IC904.
(when power is supplied and LED is lit.)
• Check whether 12V is supplied to RLY107 and RLY108 or not.
No
(Check the surroundings of Q251, Q252, R251 to R253.)
• Check whether 12V is output from IC106 or not.
• Check whether Q118 and Q119 are on or not.
• Check the line Q118 and Q119 from Pin 41 of the
microcomputer IC904.
• Check whether the proper voltage is output from the power
No
PWB CNW503 or not.
• Check whether RLY106 is activated or not.
• Check whether Q116 is on or not.
• Check the line Q116 from Pin 42 of the microcomputer
IC904.
• Check -22V (around Q115 and Q114).
• Check 5V (around Q105 and Q106).
No
• Check reset 5V.
(Connection from Pin 21 of the microcomputer IC904.)
• Check CNS601A/B and main volume, VOL601.
No
• Check the IC107 output voltage which is supplied to drive
the relay.
• Check the relays RLY601 and RLY602 and drive circuit.
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SM-SX100