elnaldo
Lunatic Member
Hello. Working in this sound interface (8 channels, analog input and analog outputs, plus firewire), and I'm having this "noise" in all the outputs and all the channels, even headphones.
https://www.presonus.com/products/FireStudio-Project
Traced with the scope and the noise is present at the very 1st OPamp after the input.
I was thinking in a power supply problem, it's a switching mode PS, but the output seems OK (at least I don't see a noise following the output pattern). Even at each IC, V+ and V- look flat, with minor noise probably from the SMPS.
One diode on the power supply output looks replaced (rectifiers before the voltage output, not at the primary side)
Another detail. If I shut down the unit and power ON again, the noise could be gone. Sometimes it's noisy, sometimes not. I've ran out of Freeze spray trying to identify a guilty part with no success.
What do you see in this 1KHz waves?
Thanks!
https://www.presonus.com/products/FireStudio-Project
Traced with the scope and the noise is present at the very 1st OPamp after the input.
I was thinking in a power supply problem, it's a switching mode PS, but the output seems OK (at least I don't see a noise following the output pattern). Even at each IC, V+ and V- look flat, with minor noise probably from the SMPS.
One diode on the power supply output looks replaced (rectifiers before the voltage output, not at the primary side)
Another detail. If I shut down the unit and power ON again, the noise could be gone. Sometimes it's noisy, sometimes not. I've ran out of Freeze spray trying to identify a guilty part with no success.
What do you see in this 1KHz waves?
Thanks!