Snagged an SX-3700 and went to put it through its paces, but got nothing on both A and B speaker outputs. There's no relay click. Upon visual inspection, no caps are bulging (with the exception of the two large 50v8200uF ones, but I believe that is slight warping of the plastic lids they have). Fuses are not blown. I worked all of the switches and pots quite a bit in the hopes a dirty one was the culprit, but no dice. I'm now hoping for some of the infinite wisdom from you find folks. Oh, and levels show, but only when the B speaker switch is off.