Hum after recapping - Printable Version
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Hum after recapping - mrmurr2003 - 10-29-2019
I just finished recapping my Farnsworth AC-70. I am getting a very slight hum still when I turn it on, nothing compared to it's original level, and I was wondering if there were other sources that could create it (tube?). There is very little on the internet though what I did find indicated that some radios just did hum even when new. I am also considering I might be too picky? Any feedback would be great!
RE: Hum after recapping - Phlogiston - 10-29-2019
I am leaning towards you being "too picky" because I am too picky as well. Some of the old 20s radios hum, noticeably IMO too much, but that is the way they are. Beyond that , fixing them to not hum is in fact modifying them, something I generally won't do.
Thirties (1930s) radios are generally better, but the better is usually tied to the original price.
If you are sure that you rebuilt it correctly, what you are hearing is likely normal.
The questions people are going to ask are:
Does the hum increase with volume?
Does the volume and tone control(s) seem to work properly? Have they been cleaned - with the right compound?
Have you or anybody added an input - phono, MP3 or other?
On a transformerless model, sometimes (very seldom) hum can be reduced by reversing the power plug (at the wall socket). This is more common with ground loops created by adding the above input devices.
RE: Hum after recapping - mrmurr2003 - 10-29-2019
Ok, my being picky is good. I actually had to put my ear to the speaker to hear it. The slightest increase in volume and it is undetectable. I just didn't want to cause any harm by letting it go like that. No additional inputs added and, because of very little free time, recapping took two weeks (literally replacing one cap a night) so I was slow and methodical (aka "picky"). Thanks for the reassurance. It's my first radio. Glad I didn't burn the thing up!