Jaxson: I have the 576 I think it is, one of the early hdmi units.
The hdmi board sits horizontal, above a nice heat source, = awesome design.
I replaced the caps myself a few years back after it stopped syncing with the TV.
All worked again fine.
Just recently it spat some eprom error and scared us all.
Cycling the power it went away and hasn't come back.
Time for a new one me thinks, but interesting to hear about the replacement board thing. I'll go and see if I'm on the list.
It is pretty fiddly though, not impossible, but as always with those flaky ribbon cables, it's risky if you don't have spare parts available should something break.
I think I had the same one if it's this
http://www.uk.onkyo.com/en/products/tx-sr576-34923.html
Did Dolby Digital Plus (no TrueHD). It worked great with my PS3 as the PS3 decoded Dolby TrueHD internally and output bitstream over HDMI which the Onkyo could handle.
I imported mine from ebay and one day the HDMI board died.
I tried the caps replacement and it didn't work and since it was an import I could not get local warranty support. It ended up in the recycle bin!