Is an extremely quiet hum acceptable? - Printable Version
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+--- Thread: Is an extremely quiet hum acceptable? (/showthread.php?tid=1614)
Is an extremely quiet hum acceptable? - scooby214 - 01-08-2009
I did a search before posting this new topic, but the results just gave me more questions...
I'm loving my first Philco, a 46-200, and have been listening to it a lot since it arrived. Now that I've been listening to it a while, I've noticed that it makes an extremely quiet hum that seems to be coming through the speaker. It is so quiet that I can only hear it when the volume is turned all the way down and I am close enough to touch the radio. The noise doesn't bother me, but I don't want to let it cause problems for the radio.
FYI... The large filter cap has been replaced, and a couple of the paper caps have been replaced (with an orange drop cap). (The seller claimed he tested or replaced the paper caps, so I figure he meant the other paper caps tested okay.)
Do I need to be immediately concerned with the buzz, or is this normal for a low-end Philco? I probably would've never noticed it, except I have been fooling around with the radio so much. The buzz is quieter than the amplifier hiss in many of my old Panasonic transistor radios.
Re: Is an extremely quiet hum acceptable? - codefox1 - 01-08-2009
Unless all the paper and electrolytic capacitors have been replaced, there is a chance you will have some residual hum. With half wave rectifiers, this will be mostly 60 hz, and most small speakers will reproduce this with much amplitude. That is unless you have young ears.
There is one other thing, try reversing the plug in the AC socket, or move the radio to another part of the room. Lamp dimmers, battery chargers, flourescent bulbs, pc's and other modern devices can cause interference.
Re: Is an extremely quiet hum acceptable? - Ron Ramirez - 01-08-2009
Some of my sets have a little residual hum, with all new paper and electrolytic capacitors...and I don't worry about it.
If your 46-200 still has any old paper caps, you had better replace them to avoid problems later!
Re: Is an extremely quiet hum acceptable? - scooby214 - 01-08-2009
Ron Ramirez Wrote:Some of my sets have a little residual hum, with all new paper and electrolytic capacitors...and I don't worry about it.I do plan on replacing the paper caps. There is a member of my local vintage radio club who advertises repair/restoration on the club website. I plan to contact him this weekend about either selling me caps or giving the radio a full checkup and instructing me on how to do any needed repairs. I will be happy to pay him for his expertise, but I want to do the actual work. I am hopeful that he will be interested in giving me some instruction.
If your 46-200 still has any old paper caps, you had better replace them to avoid problems later!
OT... Enjoying listening to the BCS national championship game on my Philco.
Re: Is an extremely quiet hum acceptable? - planigan - 01-09-2009
scooby214, hi. I don't think minor hum that you discribe is a problem. As with other things in life we never obtain perfection. A little hum is inevitable. I note that you said the "the large filter cap has been replaced". That set has a 30/25/20 mfd electrolytic, all in one can. Do you mean all three caps were replaced (e.g. large = the entire can) or the large 30 mfd was the only one replaced. All the electros should have been replaced. PL
Re: Is an extremely quiet hum acceptable? - scooby214 - 01-09-2009
planigan Wrote:scooby214, hi. I don't think minor hum that you discribe is a problem. As with other things in life we never obtain perfection. A little hum is inevitable. I note that you said the "the large filter cap has been replaced". That set has a 30/25/20 mfd electrolytic, all in one can. Do you mean all three caps were replaced (e.g. large = the entire can) or the large 30 mfd was the only one replaced. All the electros should have been replaced. PLGreat question. All three caps were replaced. The seller did a clean job of soldering them in, but I will have to remove one of them (and later replace it) to provide access to one of the paper caps. I was able to write down the values of most of the paper caps, but I couldn't get to that one. I hope the schematic is accurate.