Howdy, Looking at this CD player for a friend. He said it was humming along with the music. (Perhaps it doesn't know the words?) Both channels. I don't usually work on these, but thinking it was possibly a bad ground on the output RCA's I agreed to crack it open and have a gander. Short story is that the hum is somewhere else. I've pulled and measured the power supply (filter caps) and they're within 20%. I even subbed in a couple new caps there to zero effect. Swapped out the LM op-amp chips and still... hum Lifted 1 leg of the main diodes and they test good. I am suspicious of the 78XX series regulators in here, but not crazy about going full rabbit-hole without some assistance (or at least a shove in a meaningful direction). Anyone conquer this hum on a similar unit? (Phillips/Magnavox). I have Multimeters, oscilloscopes and function generators available and probably a frequency counter somewhere. Thanks.