Another thing to check. See the jumpers at the bottom in the back? If theyre not there, you can jumper them with RCA cables. One is a pre-out, and the other is a main-in. If you remove the jumpers, you can use it as a preamp, or a power amp...but not an integrated amp.
Whatever it is probably isnt too hard to fix. Im still thinking fuses. Even if it had some other faulty parts, youd still get some sort of sound out of 1 channel atleast
I love them old 'suis. A guy I used to work with had an old tube Sansui integrated amp he bought at the PX stationed in Okinawa back in the 60s...tried like hell too buy it off of him, as he didnt use it for 30 years. Back about a year ago, I got ahold of him and asked if he was ready to sell it yet. Bastard sold it to somebody for $250. The output transformers alone are worth 3x that much. The good part, when Sansiu went "Best Buy", the good engineers left and started their own company, Hashimoto, that still produces very nice gear. These are the transformers in that old unit my coworker had.