I have a pioneer VSX-819H-K (https://www.pioneerelectronics.com/PUSA/Home/AV-Receivers/Pioneer+Receivers/VSX-819H-K) and It has a problem of sometimes not playing sound. It will be perfect for 30 minutes then all the sudden it will cut off, then there will be no audio from any of the ports (I've tested them all). Some days it works perfectly the whole day, some days it won't work at all. It's starting to really piss me off because I can't seem to figure out what the problem is. I found that if there is no sound and I leave the device on for two hours with nothing plugged into it, then it will sometimes work again but I can't tell if this is mere coincidence or if I'm onto something. Any help, suggestions, or anything would be much appreciated.
Is the receiver going into protection? The front panel usually will indicate if it is.
If that's the case you could have a bad speaker or speaker wire. Disconnect them one at a time at the back of the receiver. If the receiver comes back then that wire or speaker is bad.
If the receiver is just silent but seems OK otherwise then you may have a problem with the HDMI board,. Does the problem occur with the radio or analog inputs? If not then the HDMI board may be bad.
Given the original price of the receiver repairing is probably going to cost you as much as replacing it with a more up to date unit.