I just Ebayed a pair of powered wedge monitor speakers. One is fine. The other has a mains frequency hum. Symptoms;
Turning up the gain has no effect but turning up the master volume to max causes the hum to increase slightly.
I swapped the EQ sections between units and the hum stays with the amp.
There is an audible (mechanical )transformer hum. I fact, I think I can feel it vibrate.
Can transformers go bad like this? I've only ever seen complete failure.
Turning up the gain has no effect but turning up the master volume to max causes the hum to increase slightly.
I swapped the EQ sections between units and the hum stays with the amp.
There is an audible (mechanical )transformer hum. I fact, I think I can feel it vibrate.
Can transformers go bad like this? I've only ever seen complete failure.
transformers can develop "magnetic slap" over time as some of the laminations work themselves loose of the lacquer holding them together. this is easily cured in most cases with a syringe full of a wood finishing lacquer (if the loose plates are visible and easily reached) or re-dipping the transformer in lacquer. as far as the amplified hum, is it really loud or background hum? loud hum could be caused by a shorted output device (which would also cause the transformer to vibrate). background hum could be caused by a number of things, bad caps in the power supply, a loose ground wire in the eq stage, etc...
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