All:
I am reading with some distress the replies to HMmmmmmmm. I will refrain from true snarkiness in deference to the moderators, but Really!
a) The hum developed apart from any changes in the system.
- This eliminates ground loops as the cause. Full Stop.
b) The hum is on both channels, all the time.
- This pretty much eliminates external component problems.
c) The hum is also on the transformer.
- this is systemic, and probably load-related.
Nothing in the original post, nor in the component design suggests or implies that a 3-prong cord would solve anything related to the issue. Worse, it might mask a developing problem in the transformer, rectifier or filter caps.
When making a diagnosis:
1. Eschew needless complexity - do not 'multiply entities' as William of Occam stated.
2. Do not utilize solutions for problems that do not exist.
3. Be systematic.
4. Follow the evidence. Gather data. Eliminate possibilities. Follow probabilities. Taking one path eliminates other paths - so, again, FOLLOW THE EVIDENCE!
5. If nothing else, create a flow-chart starting from before the problem to where things are now, marking any change to the equipment or its environment.
I have to step back some on this rant, as over the last 45 years in the hobby, I have accumulated a reasonable amount of basic test equipment and some exposure to unusual conditions that others have not. But, that does not mean that much cannot be learned from a basic VOM and basic (but cautious) tests.
BUT,
PLEASE,
DO,
NOT,
Advocate tests and solutions that are not specific to the condition(s) described, nor could they be. That is both dangerous to the equipment and to its owner.
I am reading with some distress the replies to HMmmmmmmm. I will refrain from true snarkiness in deference to the moderators, but Really!
a) The hum developed apart from any changes in the system.
- This eliminates ground loops as the cause. Full Stop.
b) The hum is on both channels, all the time.
- This pretty much eliminates external component problems.
c) The hum is also on the transformer.
- this is systemic, and probably load-related.
Nothing in the original post, nor in the component design suggests or implies that a 3-prong cord would solve anything related to the issue. Worse, it might mask a developing problem in the transformer, rectifier or filter caps.
When making a diagnosis:
1. Eschew needless complexity - do not 'multiply entities' as William of Occam stated.
2. Do not utilize solutions for problems that do not exist.
3. Be systematic.
4. Follow the evidence. Gather data. Eliminate possibilities. Follow probabilities. Taking one path eliminates other paths - so, again, FOLLOW THE EVIDENCE!
5. If nothing else, create a flow-chart starting from before the problem to where things are now, marking any change to the equipment or its environment.
I have to step back some on this rant, as over the last 45 years in the hobby, I have accumulated a reasonable amount of basic test equipment and some exposure to unusual conditions that others have not. But, that does not mean that much cannot be learned from a basic VOM and basic (but cautious) tests.
BUT,
PLEASE,
DO,
NOT,
Advocate tests and solutions that are not specific to the condition(s) described, nor could they be. That is both dangerous to the equipment and to its owner.
Last edited by Peter W. on Tue May 29, 2018 1:47 pm; edited 1 time in total (Reason for editing : #$%^&*( Auto-Correct!)