EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: lordvader88 on June 11, 2019, 10:18:37 pm
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I have a little Logitech x-540 5.1 surround system for my computer, and it has a problem sometimes, like the output has some tremolo guitar pedal type effect, or some phasor pedal effect, that is at around 2 times per second, 2Hz. It was like it from the day I got it, years ago. And it's not the PC, trust me.
The easist way to hear it is, if any sort of white/brown//etc noise is playing, on any speaker (it happens on each speaker on it's own) and the physical volume potentiometer of the logitech, is at a certain place and the problem happens, it will sound like the volume is going up and down a bit, like pulsating. I haven't figured out if the volume actually is going up/down, or if it just some interference type effect.
I can hear that's it's about 2Hz, that's always the same, so is the intensity change/per volume, so the higher the volume, the more obvious the problem. At least I don't notice it most of the time, regular speech, parts of games, etc, u just won't notice.
Now if I wiggle the volume pot up/down a bit, I can often get rid of it.
Looking at the direct output from the logitech amp, to 1 of the speakers, last year, On my Tek 2215 and Tek2430A, I can't make out anything at all, working normal or not. It's just super low voltage jumble. And worst of all, at 2Hz, my scopes are pretty ugly looking, I hate using them at 60Hz, you still don't have a nice smooth beam.
Maybe I should solder in a set resistor for a while and see if it happens then ? It would be super lucky and easy if it's just the volume knob pot that's the problem.
If it is some sort of transistor based oscillation, IDK
Other than that, it's a pretty cheap and basic circuit, with 1 big output chip, that does pretty much everything, just add some big caps.
On a side mission, I could try making some audio meter type circuits. I want some of them.