Paulo P wrote: ↑Mon Jul 20, 2020 7:43 pm
So, the solution of this problem is not simple at all and practically impossible to do if I understand it correctly? Is there any simple explanation? Or is it not over yet?
Unfortunately there is no simple solution to this. Noise is introduced on the power rails on various parts of the motherboard. It is in particular been noticed that when RAM is being accessed, it generates all sorts of additional noise... Multiply that by every trace on the PCB... But because a lot of this board is running in the megahertz range, noise simply gets transmitted and coupled to other traces which compounds the problem which all ultimately ends up in the audio system.
As I said in a previous post, the entire DAC & audio system would have to be designed on a better PCB. Maybe even run on its own power rail. And would likely need to be screened in a container to stop the RF pickup as well.
The DAC fix PCBs I did for people to test, this did solve some problems, but as far as simple fixes go, I don't believe there is anything else which can be done other than rebuilding the whole circuit.
Really,we have to accept that these computers ( like many others) were built to a price. They not going to invest months of research in ironing out all these little issues. But back in the days of TVs, maybe was just not simply noticeable, or the TV amplification was just so bad it never reproduced the noise anyway. But again, these are low-cost computers and built to a price,. Works yes, works good, not so much
So it is over until someone takes on the challenge of rebuilding the circuit and continuing the investigation. Though I think no one will really have the time interest or motivation to do such work. This thread is already over two years old now