Humming Sound?

[PE VSX 95]

Can some one point me in the right direction with handling a humming sound i am hearing when i turn on my Pioneer Elite VSX 95. The sound is coming through the speakers. Is it something i need to look for and can fix? Or is it a professional repair?

[mgoyack]

I am having the same problem, sounds like a buzzing. I have disconnected ever component from the receiver and the speakers still buzz. the volume of the buzzing does increase and decrease with the volume control.
Any ideas as maybe a fualty relay chip that turns on and speakers a and b ?? or a bad ground some where in the receiver. the over all receiver is grounded ok though.

[Guest]

[torbjorn]

If the hum disappears completely when turning down the volume control, then the hum source must be before the volume control in the signal chain.

Check out the supply voltages for the preamp stages if there is any ripple on them. Common reasons are dried out electrolytics in the power supply, faulty voltage regulators (three-leg regulators like 78xx or semiconductors in regulators built with discrete components), or open-circuited diodes in rectifier bridges. In case of symmetrical power supplies with a grounded center tap on the transformator secondary, also check any fuses or fusible resistors between the transformer and rectifier.
In the last case, the hum will always be of mains frequency (50 or 60 Hz), but if the bridge rectifier operates properly and there is a filtering or regulation problem, then the hum will be double the mains frequency (100 or 120 Hz).

Make sure that you have access to an oscilloscope and to the service manual for the receiver before commencing with troubleshooting.