So I've had this issue ever since getting my 58 back in the summer.... i brought it in for repairs for a separate issue (which turned to be the motherboard/main control chip was fried, I was lucky enough to get a new one on ebay) and just got it back. I mentioned the hum issue to the tech but i guess he didnt notice it, or thought the new control board fixed it... but alas not. So back to the shop in a few days it goes.... but hopefully someone here might have some ideas that could help.
So there is hum on every channel output, only in repro... and the hum isnt printed to the tape so the problem lies after that in the circuit somewhere. The hum is pretty much the same volume on every channel except ch7 where its a bit louder. I can make the hum go away by pressing on the bottom plate of the machine, or by pushing in hard the rca output cable (rca outputs only on this 58) I've read there can be issues with the way the 58's rca jacks are mounted.... since the hum goes away when different areas of the machine have pressure applied, could this be something simple like a bad contact/ground on one of the outputs? or something not grounding properly inside the machine? possibly the louder humming output is the culprit & spreading the hum to the other outputs as well..? Sorry, not a very technical guy, but maybe someone here has encountered this
Thanks for any help