two.dogs
Active Member
Still trying to solve this problem - also have a thread at Diyaudio. I think the hum is the fault of Sansui engineers. Let me restate that the only things I've done is to recap and put in new transistors - no design changes. This receiver hummed before and after the recap. I have another unmolested Sansui 5000A that has the same hum. I've also seen other threads complaining about hum with this model. Hum is unaffected by volume and occurs at all inputs (even when shorted).
According to this writeup (Grounding and Shielding for your DIY Audio Projects) there should be "three separate grounds; the signal return, the power supply return, and the chassis." But here is the way this receiver is built...
John
According to this writeup (Grounding and Shielding for your DIY Audio Projects) there should be "three separate grounds; the signal return, the power supply return, and the chassis." But here is the way this receiver is built...
- Signal return - through the chassis
- Power supply return - through the chassis
- Chassis - two wire plug with no ground. Mains are referenced to the chassis through a capacitor and 1M resistor.
- Connected a source (iphone) to the aux input of the receiver, then ran the preamp output to a T-amp and speaker (see pic). Good sound with no hum.
- Connected a source (iphone) directly to the amp driver board with speaker connected to the Sansui (see pic). Good sound with no hum.
John