My VSX-816 center channel was dropping out after having it for several years, and it has been getting worse over the past few months. I tried the usual jiggling and re-doing of speaker connections but no joy. I noticed that using the remote to switch to Stereo only mode and back to Auto Surround would bring the center channel back. The speaker relays click when you do this.
I took it apart as dandersox suggested and de-soldered and removed just the center channel speaker relay, since that was the only one causing problems for me. I pried the case off the relay and lightly burnished the contacts with a single pass of #600 emery cloth. There is no glue holding the relay case on, just a couple of tabs on the sides. I broke one getting it off, but it still snapped back together. I needed a third hand to help hold the relay in place while re-soldering.
I also re-soldered a few other solder points that looked suspicious: the 2 chips that stick out from the side of the board and screw down to the bottom chassis, and a center channel jumper wire.
I don't know if dandersox was exaggerating about having to remove 35 screws, but I managed it with just 13 screws and 1 plastic push pin. I did not unplug anything inside the chassis.
Here are the steps:
1. Remove 6 top cover screws: 2 on 1 side, 1 on the other side, 3 on back (lower corners, top center), then remove top cover.
2. Remove 1 back case screw at lower center. This holds the back panel in place, along with a metal tab beside it.
3. Remove 2 copper screws holding heat sink assembly to chassis bottom.
4. Remove 2 screws holding the 2 chips to the chassis bottom behind the power transformer. There is no heat sink grease on these.
5. Remove 1 screw on the transformer side of the chassis that holds the power supply board to the chassis.
6. Remove 1 screw on other side of chassis that holds the main board to the chassis bottom. There are holes for 2 screws here, but mine only had one installed.
7. Remove 1 plastic push pin behind the Multi Jog dial that holds the long circuit board in place. Push on the small tip of the pin on the component side, then carefully pull the opened pin from the board.
8. Unwind the black coated wire behind the push pin that holds several grey wires in place, and pull the wires loose.
9. Carefully flip the chassis over, resting the top of the receiver on your table.
10. Rotate the bottom of the chassis upwards, pivoting at the front. Prop it up with some wood or whatever to allow access to the solder side of the main board.
The speaker relays are lined up with the speaker outputs on the back panel that they control. Lettering on the circuit board identifies them. I outlined their locations with a magic marker to make life easier. Be careful to not solder the very small diodes under the main, surround, and surround back relays.
I have never noticed the fan running in mine either. Presumably it only comes on at high power levels, so you probably wouldn't hear it over the speakers except during quiet pauses. I was worried about overheating, since it is mounted in a cabinet with only a 2 inch space both above and below the receiver (the feet rest on rails), but wide open at both front and back. One advantage of this setup is that no dust has collected inside even after 4+ years.
Attached are some pictures. I have more if anyone is interested.