Sharp MD-X7H Service Manual page 111

• Although HF waveform is normal and time
indication is normal, no sound is not output.
Check the IC2 pin 48 (EFLG).
Check the IC2 pin 37 and pin 40.
Check IC501 and POWER AMP. IC201.
Trouble-shooting (Amp section)
• When the power supply is turned off (POWER
OFF), and the "PROTECT" blinks
Is IC901 pin 49 PROTECT input in Low
state?
Yes
Check
Is Q260 in ON
and Q260.
state?
Yes
No
Check IC201,
Is Q297 collector
Q297 and Q298.
voltage 0V?
Yes
No
Check Q251.
Is Q251 collector
voltage 0V?
Yes
No
Check Q252.
Yes
Yes
Monitoring the IC901 pin 49, press the
POWER key to turn on the power
No
supply again.
IC201
The state of pin 49 of IC901 is changed from H to L, and the power supply is turned off
again, resulting in "PROTECT" error.
Monitor the Q297 collector when the
power supply is on.
Is the state changed from H to L?
Monitor the Q251 collector when the
power supply is on. Is the state
changed from H to L?
Monitor the Q252 collector when the
power supply is on.
Error due to detection of abnormal
temperature rise in IC201After
cooling the set turn on the power
supply again.
The state of pin 49 of OC901 is changed from H to L, and the power supply is turned off
again, resulting in "PROTECT" error. Check IC201.
Usually, the number of pulses of flawless disc is 100 pulses/sec or
No
less.
Yes
No
No
Yes
No
Yes
No
Yes
No
Yes
No
– 75 –
The pin 49 of IC901 keeps High state,
and normal rise is ensured.
Error due to DC detection
Check IC201.
Check the power circuit.
Error due to Lch side overcurent detection
Check for short-circuiting on the L-ch side
SP terminal and subsequent parts.
Error due to Rch side overcurent detection
Check for short-circuiting on the R-ch side
SP terminal and subsequent parts.
The pin 49 of IC901 keeps High state, and
normal rise is ensured.
MD-X8H