Really awkward humming coming from my AV Receiver.


Oct 29, 2017
Alright, I'll start with what the receiver is. It's a UBX (UBR510B) that I found on the cheap in a store about 1.5 years ago. It's honestly pretty garbage, and doesn't handle electricity well at all, but it is all that I currently have. When powering on, it immediately throws it's power to the speakers rather than building it up, causing the usual popping, and when powering down, it just cuts the power, resulting in a relatively normal whirring sound as the speakers lose power. That's relatively normal; what I'm used to and what I've come to live by.

Yesterday while listening to music, suddenly the AV Receiver did the usual popping for powering on the speakers, however, they were already on. It went crazy for about another 5 seconds before basically adding a loud constant humming noise. The humming persists throughout all the channels, even the radio, is on all speakers, and cannot be adjusted via the volume. It is absurdly loud, and makes the receiver unusable. Another thing to note is that the sound was added. It can still process audio and send it through the speaker, but the humming persists all throughout.

Now, no matter what I do with the AV Receiver, whether hooked up to anything or not, and no matter with what speaker, it's blasting a humming sound through. I've opened up the Receiver twice, once to fix the Volume Encoder a few months ago, and again yesterday to see if any resistors/capacitors are broken or if the solder was burnt or so. There was no visible damage, however, I'm convinced that one of the more unique components inside is broken. I myself am not sure which component it is, and haven't worked with all too many receivers. I've looked everywhere for the circuit diagrams or a teardown of the Receiver, but there's nothing for information anywhere.

I'm well aware of the usual quiet humming that some speaker/AV Receiver set-ups have when they're set up incorrectly. The problem mentioned above is not that as far as I know. The humming is way too loud and not just a minor wiring mistake. I'm also aware as to what the popping is and all that. I've adjusted to that and basically been living with it normally, knowing that the cheap UBR510B is at fault. All I'm looking for is some sort of guidance for how to fix the loud humming and to restore the Receiver, making it at least usable again.

UPDATE: After having seen the remark about the PS Caps being whack, I've reopened the receiver to double check. I did find a capacitor that I've actually never seen before, which would explain why I dismissed it previously. Its a HuiKe capacitor, so It was more or less hard to recognize any visible damage. I'll look into buying a replacement capacitor and actually replace it in the near future. Until then, this is the most likely broken component.
My guess would be the powers supply caps are bad. That would allow 60hz hum to come through, If the power supply is a switching type then it's more complex. Usually requires a tech or at least some soldering skills.