Repair procedure: open cover measuring AC 220 volts is entering the tank, RX-V459 no AC switching power supply standby transformer directly, after the rectifier circuit plug CB3 output to the CPU board, CPU power on command-and-control work main relay main transformer. Measure voltage on the CB3 are as follows:2VDservice manual download site
S10:10 v PRY:0 v PDET:0 v +5M:5 v/RES:5 v.2VDservice manual download site
2VDservice manual download site
Instructions the standby power supply properly, PDET at 0 Volts is not normal, measuring CPU 2nd foot, 21st, 37th foot and 85th foot operating voltage of 5 volts is normal. Measurement of the 17th PIN reset voltage of 5 volts is normal. 18th foot, the 20th foot external Crystal oscillation waveform on both ends, and explain the reason for CPU is not working properly it is not turned on. PDET plug wire disconnected, no voltage measurements at both ends, separate PDET 5 volt supply on the CPU side,2VDservice manual download site
Voltage becomes 0, description has short-circuit, measurement its on to resistance for 50 Europe, obviously exception, cleanup circuit, PDET feet from CB3 entered circuit board yihou, is divided into two road, along to regulator Board tube D6, along to CPU30625 of 96th feet, split Xia 30625 Hou measurement circuit board, no longer short-circuit, does is 30625 damaged has, this situation not too may, will 30625 introduction feet all short received discharge Hou measurement introduction feet also no longer short-circuit, seems this short-circuit is a illusion, Place the chips returned to Chongqing after it PDET feet. PDET in stand-by power plate from trigger TC4013 on one side, and after trying to replace 4013, PDET voltage is restored. Power on the machine working properly.2VDservice manual download site
2VDservice manual download site
Worth noting is that Yamaha amplifier repair this case is very common, and in many cases easier to technician error-CPU is damaged, and after our repair proved, at least for now to this machine, there is not a single CPU is damaged.2VDservice manual download site