08.05.2017, 10:55
Hallo Ken,
a possibly similar case was reporteded recently, where somebody observed a strong humming sound at low supply voltages (below the recommended ?5.5V?). At those low voltages the decoupling function of the supply voltage regulation vanishes resulting in low frequency oscillation of the audio pre-amplifiers.
Is only one channel affected by the problem ?
I could imagine that failure (loss of capacitance) of another electrolytic capacitor in a channel strip could lead to relaxation oscillations that might produce the observed noise.
Could you estimate the pitch or repetition rate ?
Do you have the service manual & schematic ?
Regards Kai
a possibly similar case was reporteded recently, where somebody observed a strong humming sound at low supply voltages (below the recommended ?5.5V?). At those low voltages the decoupling function of the supply voltage regulation vanishes resulting in low frequency oscillation of the audio pre-amplifiers.
Is only one channel affected by the problem ?
I could imagine that failure (loss of capacitance) of another electrolytic capacitor in a channel strip could lead to relaxation oscillations that might produce the observed noise.
Could you estimate the pitch or repetition rate ?
Do you have the service manual & schematic ?
Regards Kai