Good advice.Check your inbox Barry, I replied to your inquiry and got you covered.
FYI, I did a little looking and this chip seems to be prevalent in many of the AX- model receivers as well. Perhaps a wise person would do well to snatch up any parts unit they come across if they can verify its presence.
I've got an MX-1 and it would be a damn shame if it lost a channel due of a bad HCA IC. AK'er amr2 researched which Yamaha gear used the BA3122N, and here's a link to the thread he started:
http://audiokarma.org/forums/index....perbolic-conversion-amplification-hca.737425/