Hi there,
Have you looked at the amount of ripple voltage on the power supply feed. If it is high, it may indicate a faulty power supply rectifier or capacitor. The sound being a 'buzzzzzz' more that a hum would confirm that. Do you have another power supply you could test it with to check this?
Hope this helps,
Mike
Have you looked at the amount of ripple voltage on the power supply feed. If it is high, it may indicate a faulty power supply rectifier or capacitor. The sound being a 'buzzzzzz' more that a hum would confirm that. Do you have another power supply you could test it with to check this?
Hope this helps,
Mike
When you buy an old piece of equipment (this one looks to be at least 40 years old), some if not all of those electrolytic capacitors will be original and probably well past their useful lifetime. Replace them - all of them, including the little coupling capacitors, because the buzz is most likely due to their failure.
This then points to something in common to them which is probably the power supply.
As Nigel has suggested, the likely culprits are the power supply smoothing capacitors and they will need replacing.
Regards
Mike
I have replaced the 3000uf 25v filter capacitors with new equivalent capacitors but still have a buzzing noise
I have replaced the 3000uf 25v filter capacitors with new equivalent capacitors but still have a buzzing noise
Looks to be an old selenium rectifier in this one 😱 I think I would look at replacing that with a new chassis mounted rectifier.
You need to test the buzzing with only speakers connected and with the inputs (or at least the selected input) shorted.
High quality scanned circuit here:
Alba UA 700 Solid State Integrated Amplifer Manual | HiFi Engine
You need to test the buzzing with only speakers connected and with the inputs (or at least the selected input) shorted.
High quality scanned circuit here:
Alba UA 700 Solid State Integrated Amplifer Manual | HiFi Engine
I think this may be a language / semantics thing. I assume buzzing (from speakers) may be what is normally called “hum” from the mains. Hum from mains might be due to PSU caps or bad rectifiers - but as the caps were replaced, it may be from a ground loop or inadvertently contacting signal ground to chassis ground somewhere. A few more closeup photos at oblique angles rather than straight rectilinear may show us more detail to help debug.
It is not clear that the aluminum chassis has a connection to earth/mains ground. Try grounding the chassis and see if it helps. Maybe use a 10ohm resistor ground loop breaker.
It is not clear that the aluminum chassis has a connection to earth/mains ground. Try grounding the chassis and see if it helps. Maybe use a 10ohm resistor ground loop breaker.
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Mooly has provided a link which gives the amplifier specs. The line level input SN ratio is only 63db. The buzzing if its a low level might be normal. Is the buzzing noise the same on all inputs? You mentioned the buzzing gets louder as you turn up the volume. Check the shielded cable ground connections.
I check the ground connection of everything is fine, I found the "hum" in the Loudness floor of amplifier, when I turned down the Loudness button, the phenomenon no longer exists.
"hum" sounds when not connected to input devices. I broadcast the loudness floor got "hum"