Don't know if anyone is still looking at this thread, but just in case:
I tried the kitchen wall outlets; no change in the hum. What does this mean? Does it mean that the problem is not "DC offset"? That I would not therefore benefit from a DC Blocker? (I notice that the "Humdinger" site says that device will NOT cure a hum caused by a faulty transformer, although it might reduce it.) Remember that the "old" unit never hummed in 30+ years of operation, and none of my other audio devices hum even now. So the problem does seem to be in the transformer, and not in the wall power. Still, I'd love to believe a DC blocker would help; that would be the easiest, and cheapest, solution.
chris_w_uk: thanks for your suggestion! I think, finally, it's my best bet here: a DIY "re-potting" with 555 varnish and an oven. But the link you provide is not, as far as I can tell, to a business that could do this for me. For one thing, it's in Mumbai! No way I'm sending this very heavy, and apparently vulnerable transformer to India.
I tried the kitchen wall outlets; no change in the hum. What does this mean? Does it mean that the problem is not "DC offset"? That I would not therefore benefit from a DC Blocker? (I notice that the "Humdinger" site says that device will NOT cure a hum caused by a faulty transformer, although it might reduce it.) Remember that the "old" unit never hummed in 30+ years of operation, and none of my other audio devices hum even now. So the problem does seem to be in the transformer, and not in the wall power. Still, I'd love to believe a DC blocker would help; that would be the easiest, and cheapest, solution.
chris_w_uk: thanks for your suggestion! I think, finally, it's my best bet here: a DIY "re-potting" with 555 varnish and an oven. But the link you provide is not, as far as I can tell, to a business that could do this for me. For one thing, it's in Mumbai! No way I'm sending this very heavy, and apparently vulnerable transformer to India.