Symptom: after start-up the power standby button, main relay HA, hear the relay disconnects after about three seconds the display, display is off, reboot again, too, stumbled on can sometimes open a few more times normal, but normal again and open the phone can work properly. Feels like a machine after the heat is normal.MrSservice manual download site
MrSservice manual download site
This phenomenon can be characterized as a soft failure, so-called soft fault is that there is no obvious defects, sometimes good and sometimes bad, with instruments and equipment are not easily measured parameters exception fault. Hard failure refers to the clear symptoms, have a fixed fault occurs, will eventually find significant damage components.MrSservice manual download site
MrSservice manual download site
When the machine works properly when measuring the voltage, static equilibrium, the midpoint voltage, found no abnormalities. Cooler fault appears, try using hot air heating circuit board to boot correctly, explain the reasons for failure is caused by a bad component performance. For quickly finding the target component modified electric chrome iron heats the circuit one by one, when it comes to Q515 when working, after changing the Q515:C2229, after much trial and failure did not reappear.MrSservice manual download site
MrSservice manual download site
This fault is Yamaha amplifier Yamaha 690 does not power on protection of typical symptoms,MrSservice manual download site
MrSservice manual download site
Because of its many protection circuit is designed, such as leakage, short circuit, poor contact, and so on, and sometimes repair the machine did not protect cable plugged in. More Yamaha amplifier maintenance refer to the other article.MrSservice manual download site