The DSP-A2 fault when sent to a repair shop for: normal power operation, front-channel sound normal, middle and surround from time to time, sometimes after boot time sound, sometimes disappear after boot time a voice sometimes hoarse.fwqservice manual download site
At first glance this phenomenon seems to be more complicated, teardown machine structure is more complex, but our Yamaha amplifier maintenance a lot, its circuits are more familiar with it.fwqservice manual download site
fwqservice manual download site
Transformer and circuit board inside the machine room was full, fortunately has a maintenance window at the bottom of the machine can be broken down or change what part needs to be removed so many boards is a major headache for today, @# I did was to be very thoughtful, this sense of domestic manufacturers should learn. Experience and practice have proved that the symptoms, the more complex machines, from the simplicity of the place you want to start,fwqservice manual download site
fwqservice manual download site
Sometimes there are sound amplifier level after no problems because after Yamaha amplifier circuit usually these phenomena do not exist poor contact, only homemade amplifiers making process is very cold solder joint unsoldering and A2 models are high-end machines. Previous level and have problems with decoding, it can use an oscilloscope waveforms, just find the Main-In point on the line, and tests these are no problem.fwqservice manual download site
So most likely amplifier tube common to the output circuit between terminals, through a close look revealed that output relay there is water nearby and there is a little rust is an artificial inlet. Remove the relay itself has been badly corroded, replace the fault remove.fwqservice manual download site