Help, im currently repairing this AU7500, at first relay clicking in and out like crazy so i isolate Pre-amp and main in by removing horseshoe connector between them, turns out the pre amp is the problem, since i dont have an oscilloscope, i chased the 1khz signal through preamp using and earphone in series with a 200 ohm resistor and a probe, signal passes through TR701, and TR703 just fine up until the base of TR705 after that 1khz signal is kinda fading in and out through the emitter of TR705, i already replaced it and TR707 with KSA992 and it still doing it, i also replaced the electrolytic caps around it , the components around them also tested fine.. Both Channels are doing this. im just clueless now.. help..
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Have you checked the voltages of power rails on the board? Both channels having the same problem would suggest a common cause.
Yeah im thinking too much i forgot the most basic thing to check,,,, supply rails are erratic,, 2 faulty transistors from the supply board,,, works fine now,,, thanks,,,