Troubleshooting - Sharp 1-BIT AMPLIFIER SM-SX1 Service Manual

SM-SX1/SX1W
• Power is not supplied.
Does AC100V stand between Pins 1 and 2 of the power
filter PWB connector CNP502?
Yes
Is any normal voltage output from the power PWB
B1503/CNS503?
Yes
Is 5V supplied to Pin 13 of the microcomputer IC907?
Yes
Is any oscillating waveform found at Pins 14 (OSC2) and
15 (OSC1)?
• If no sound is present at the analog or digital input
Are the speaker relays RLY201 and RLY202 switched?
Yes
Are they properly wired to the 1-bit amplifying unit?
(CNWAM1, CNWAM2, CNWAM3, CNWAM4)
Is voltage properly supplied to 1-bit amplifier? (CNP306)
Yes
Is voltage properly supplied to 1-bit amplifier? (CNP305)
Yes
Is any signal output from the connectors CNP303 and
CNP304 for 1-bit amplifier?
Yes
Check the inside of the 1-bit amplifying unit.
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TROUBLESHOOTING

(LED904 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 output voltage (OYT terminal) of UNT501 and
No
• Check the parts (L504 to L511, F502, FS503 and R503 to
• Check the 1-bit amplification unit.
• Check IC306 output.
• Check R391.
No
• Check X900.
No
• Check IC907.
(when power is supplied and LED904 is lit.)
• Check whether 12V is supplied to RLY201 and RLY202 or not.
No
• Check whether Q203 and Q204 are on or not.
• Check the line Q203 and Q204 from Pin 41 of the
• Check whether the proper voltage is output from the AC
No
• Check whether RLY303 is activated or not.
• Check whether Q303 is on or not.
• Check the line Q303 from Pin 42 of the microcomputer
• Check -22V (around Q115 and Q114).
• Check 5V (around Q105 and Q106).
No
• Check reset 5V.
• Check CNS601A/B and main volume, VOL601.
No
• Check the IC107 output voltage which is supplied to drive
• Check the relays RLY601 and RLY602 and drive circuit.
– 34 –
UNT502.
R506) on the power PWB.
(Try to disconnect CNWAM4 and CNWAM3.)
(Check the surroundings of Q201, Q202, R201 to R202.)
microcomputer IC907.
input filter CNP502 or not.
IC907.
(Connection from Pin 21 of the microcomputer IC904.)
the relay.