Hello! I recently bought an Aiwa CA-W30 boombox and everything is perfect except the left speaker: when connected to the AC power it sounds like a kind of constant buzz. Guys, could you tell me why it is? when it's running on batteries, that buzz isn't heard. This is a link to a sample from the buzzing noise (the sound is amplified with Audacity, normal volume is -48db) https://voca.ro/17CJzHNM6C5w Thanks and greetings!
What happens if you swap the speaker wires? Does it do it with all functions, radio/tape/aux? I'd clean the function switch with contact cleaner and see if that changes anything or move it rapidly to see if anything changes. Sometimes other things plugged into the same system will cause havoc, like LED lights, move it to another home and see if it's the same issue.
Yes, if I swap the speaker wires the same thing happens and the noise is heard independently in radio/tape/aix. In another part of the house the same thing happens, and even in another different house, exactly the same issue. Do you think it could be a ground loop problem?
Do you have a schematic or service manual for this AIWA CA W30 ? I attach a frequency analysis done in Audacity on the file you attached. It can be clearly seen that the main tone is 50Hz, not 100Hz. I assume the device uses a full-wave bridge rectifier (this needs to be double checked on a schamtic), which would generate 100Hz ripple. I'm interested to see the schematic, cause I don't know if the power amp is a single IC for both channels or separate amps. Please also attach a recording of the original sound, without amplification.
