I experienced an issue with my Onkyo HT S3500 after years of use, wherein some of the speakers were not giving any output even if I switch on All channel out. I suspected something is wrong with the receiver as I tested the speakers individually and they were working perfectly alright. Tried to reset all the settings and it did not work well and the receiver was overheating. I am staying at Kottayam, Kerala (India) and my only option was to take it to an Onkyo service center in Chennai. And then I found the contact details for Johny (9847676840) in Fort Kochi and he fixed it. The amount was reasonable, he charged 1.5K (Last time when I took it to Onkyo Service Center, they charged my 7k for service and courier for cleaning up the chipset). The issue was that the cables connecting the boards were faulty. The terminals had a lot of greenish oxide deposits and were not connected properly. It's best to keep using the receiver so that there won't be any oxide deposits and be extremely careful while transporting the receiver from one place to another. Provide sufficient ventilation and if possible add an extra fan on top if the room is not cooled properly. Hope this helps people who are facing issues with the audio output of Onkyo HT S3500.