Onkyo TX-RZ800 completely dead

In the Service Manual for the NR616 they list the RTAN430C for this circuit but also the RN1441. They actually list the RN1441 as the primary option and the RTAN430 as the second option so I just substitute the available part. Both Mouser and Digikey offer the RN1441 but you need to act fast because this part is being discontinued by the manufacturer. Both companies still have stock (at the moment).

As for the resistors, the 0 ohm are nothing special.  I don't think you need to spec 1/2 watt, 1/4 watt carbon resistors should be fine.  In my experience, 0 ohm resistors are used for two reasons.  1) they act as a kind of a fuse and can provide some level of protection 2) In designs where two traces would cross on the PCB, they are the easiest way a designer can build a "bridge" for one trace to run under the other without using a multi-layer board (which gets expensive).  In these cases a simple jumper wire would work but the advantage of using a 0 ohm resistor is that they can use the same robotics process as the rest of the components.  The process to install an SMD device uses different machines than the process to install "through hole" devices so they gain some manufacturing efficiency by using an SMD resistor that is essentially a piece of wire.

Looking at the circuit (the 0 ohm resistors don't show up on the schematic) the R4071 touches the Main Volume chip (Q4001) so there is a good chance that it will be damaged too.  I am not sure where you will find one of these.  If you do find one, be VERY cautious with this chip!  They are VERY difficult to remove without damaging the board.  Onkyo uses a film mask applied over the PCB on this board and then they glue the chip down at 4 points.  When you apply heat to try to remove it, the solder goes molten but the glue holds the chip to the PCB.  The problem here is timing.  At the moment the solder goes molten you need to use a screw driver to break the chip free from the glue.  If you wait too long, the heat causes the film mask to bubble.  This "bubble" can be up to 1 inch in diameter which will make it really hard to get the new chip to seat properly.  On the plus side when it "pops" it breaks the chip free from the glue but now you will have one side (or two) where the traces won't be flat.  The last time this happened to me (on an NR636) I reacted quickly enough to push the film back down and hold it until it cooled.  But it was still a bit off making it hard to get the new chip to fit.

I was REALLY hoping that the damage you were seeing didn't extend this far.  As I said in an earlier post, this type of failure is the most catastrophic I have seen on an Onkyo in terms of the number of parts that it breaks.  It took me weeks to debug all of these issues on an NR636.  On the plus side, you are on the right path.  The first step is always to fix the Amplifier circuit so that it doesn't happen again (sounds like you are done here).  The second step is to fix the Main CPU damage so that it will boot again (I think you are close here).  The last step is to fix the resulting issues with the signal path (Mute transistors and potentially Main Volume chip).

One interesting note, the way I figured out that the Main Volume chip was bad on my NR636 was to use the Onkyo built in diagnostics.  One of the tests that you can run is to exercise the vProtect circuit.  What this test seems to do is to apply a small positive DC voltage to each channel - one at a time - (instead of an audio signal) while monitoring the vProtect signal to see if it trips.  The Main Volume chip has the ability to direct a signal to any channel (or all channels or any combination of channels).  As I said, the test applies a DC voltage to each channel one at a time so that it can identify which vProtect circuit is bad.  What I found was that my NR636 never detected this positive voltage so it would fail the test every time.  I was able to trace the signal up to this volume chip but it never came out at the channel so I realized that it had blown and wasn't passing the input signal to the amplifier stage.  Once I changed this chip out, it passed all the test and everything worked again.  ROYAL PITA!

Let me start with the caveat that I HATE the newer receivers and won't work on them.  I have fixed 6 NR636's and they are simply no fun to work on so I refuse to work on the newer units.  One example is the voltage regulators they are using now.  To save money (I suspect) they seem to be using parts designed for cell phones like this little sucker: TPS22924CYZPR

6 solder balls, each only 0.15mm (the DSP uses 0.6mm solder balls as a reference).  0.000060 oz in weight and (oh yeah) a reflective surface on top.  The entire device is microscopic and I need a magnifying glass just to see it.  On top of all this, they weigh nothing so they blow out of place really easily but the reflective top won't pass heat to the solderballs so you can't apply heat from the side.  This thing is a nightmare to install.

Most people on eBay don't know how to describe a problem in the first place so you never really know what works and what doesn't.  Having said all this,

1) If a device is missing audio and video I would look for a voltage rail issue.  On several of the 636's I found that the 3.3V rail was down to zero and the root cause was a blown SII HDMI Receiver chip.  The DSP system turned out to be fine but it simply had no power to run on because of the shorted HDMI chip.

2) If a device is missing only audio, I suspect that the DSP has experienced cracked solder balls.  This is MUCH more common that people think and is a bi-product of the move to Silver based solder.  Silver based solder breaks before it bends. Lead based solder bends before it breaks.  As we learned from the other thread on this site, corrupted firmware is also a possibility.

The only good thing about the newer Receivers is that they use the "D" rev DSP part which means I can buy the broken boards, remove the DSP, reball it and install it into a good design like the NR-818.