I took a 40 minute drive yesterday to pick up this beauty of a Pioneer for under $100, complete with original remote and in absolutely mint condition. The seller notified me of the 'humming' sound that it produced, played it so I could hear it, and I decided I could probably live with it (or fix it)..
Got home, connected it, and my A/D/S SAT7's make the humming even more noticeable than what I heard at his house (he tested with a pair of Bose 2.2's 🙄). This hum does not increase with volume (or any other variables), it seems to be just a constant low volume sound. It becomes much less apparent as the volume increases.
It may be helpful to mention that the power cord for this unit (which seems original) is not grounded.
I have:
- Reset the unit
- Disconnected ALL cables except speaker wires
- Unplugged ALL other units (TV, Cable, etc) from the circuit
- Attempted 3 different circuits in my house
..none of which helped.
Am I overlooking something? Any help is greatly appreciated.
Got home, connected it, and my A/D/S SAT7's make the humming even more noticeable than what I heard at his house (he tested with a pair of Bose 2.2's 🙄). This hum does not increase with volume (or any other variables), it seems to be just a constant low volume sound. It becomes much less apparent as the volume increases.
It may be helpful to mention that the power cord for this unit (which seems original) is not grounded.
I have:
- Reset the unit
- Disconnected ALL cables except speaker wires
- Unplugged ALL other units (TV, Cable, etc) from the circuit
- Attempted 3 different circuits in my house
..none of which helped.
Am I overlooking something? Any help is greatly appreciated.
Chances are, if you looked at the power amp's supply rail with a scope, one of them would have severe ripple. Either that, or the hum already comes in via the preamp.
In both cases it would be either a dead electrolytic or blown rectifier diode. (Do any 'lytics show a bulging top?) Sometimes people also observe contact problems with plugged-in ribbon cables.
The easiest way to check whether it's one of the big electrolytics for the power supply rails (which are kinda $$$) is soldering a ~1000µF with appropriate voltage handling in parallel, observing polarity. At 125 wpc, I'd guess you'd need 63V types at the very minimum, and maybe even more (82V or 100V).
In both cases it would be either a dead electrolytic or blown rectifier diode. (Do any 'lytics show a bulging top?) Sometimes people also observe contact problems with plugged-in ribbon cables.
The easiest way to check whether it's one of the big electrolytics for the power supply rails (which are kinda $$$) is soldering a ~1000µF with appropriate voltage handling in parallel, observing polarity. At 125 wpc, I'd guess you'd need 63V types at the very minimum, and maybe even more (82V or 100V).
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