Just for what it's worth the OEM service manual for the 9090 also covers the 8080. Any reference to the " Model A" version is the 9090 and the "Model B" version is the 8080 in that manual. Almost all of the components/boards in the 9090 are interchangeable with the 8080 and vice versa. It appears to me that the only difference in the two is that the 9090 is 110 wpc and the 8080 is 80 wpc.