Hello my RCA Victrola X624 is fixed thanx Renee and Denis! However, the filter caps have been replaced and like my other RCA Victrola 9Y5 it has a slight hum a little to loud for my liking I think it's 60 cycle and as I like to listen to AM before I go to sleep I tend to listen at low volumes therefore the hum is more apparent at these times. Are there any mods or maybee wire positioning changes that may improve on this or is it just inherant to this type of transformerless radio design? My other question is, both of these amps have no input or power transformer and have 12 and 35 volt filaments is this what you guys mean when you say it's an ac/dc radio?? If this where a guitar amp which I work on all the time I would check the filter caps but I just put new filter caps in both radios although I used a 100uF instead of the 80uF 150 that I replaced and a 47 instead of a 50uF 150V. Thanx Brian

You may be picking up the hum in some stage prior to or in the audio stage.
Be sure and check or replace all caps. I have restored radios where I have had to replace
EVERY cap in the thing. Especially be sure the caps from plates to grids have no
leakage and the cathode bypass caps are OK. Denis
: Hello my RCA Victrola X624 is fixed thanx Renee and Denis! However, the filter caps have been replaced and like my other RCA Victrola 9Y5 it has a slight hum a little to loud for my liking I think it's 60 cycle and as I like to listen to AM before I go to sleep I tend to listen at low volumes therefore the hum is more apparent at these times. Are there any mods or maybee wire positioning changes that may improve on this or is it just inherant to this type of transformerless radio design? My other question is, both of these amps have no input or power transformer and have 12 and 35 volt filaments is this what you guys mean when you say it's an ac/dc radio?? If this where a guitar amp which I work on all the time I would check the filter caps but I just put new filter caps in both radios although I used a 100uF instead of the 80uF 150 that I replaced and a 47 instead of a 50uF 150V. Thanx Brian

Brian:
You may have yet one more cap to replace. There should be a cap that connects from one of the leads from the power cord to the metal chassis. If this cap is leaking, sometimes it will introduce a 60 cycle hum. Your question on filament voltages...the typical tranformerless AA5 radio will have filament voltages in series that add up to line voltage, i.e. 35+50+12+12+12=121. When one tube burns out, they all go dark.
Rene
: You may be picking up the hum in some stage prior to or in the audio stage.
: Be sure and check or replace all caps. I have restored radios where I have had to replace
: EVERY cap in the thing. Especially be sure the caps from plates to grids have no
: leakage and the cathode bypass caps are OK. Denis
: : Hello my RCA Victrola X624 is fixed thanx Renee and Denis! However, the filter caps have been replaced and like my other RCA Victrola 9Y5 it has a slight hum a little to loud for my liking I think it's 60 cycle and as I like to listen to AM before I go to sleep I tend to listen at low volumes therefore the hum is more apparent at these times. Are there any mods or maybee wire positioning changes that may improve on this or is it just inherant to this type of transformerless radio design? My other question is, both of these amps have no input or power transformer and have 12 and 35 volt filaments is this what you guys mean when you say it's an ac/dc radio?? If this where a guitar amp which I work on all the time I would check the filter caps but I just put new filter caps in both radios although I used a 100uF instead of the 80uF 150 that I replaced and a 47 instead of a 50uF 150V. Thanx Brian

Hi,
If Dennis', and Rene's suggestions do not work, are within about 50 feet of a flourescent, or about 30 feet from a High Intensity Discharge light? These can produce RF, as well as lighting dimmers, or ceiling fan controls that are electronic rather than by selecting windings on the fan motor.

I would look at these as possible sources, plus you might want to flip the plug in the outlet. Sometimes this alone will do the trick on an AC/DC radio.

: Hello my RCA Victrola X624 is fixed thanx Renee and Denis! However, the filter caps have been replaced and like my other RCA Victrola 9Y5 it has a slight hum a little to loud for my liking I think it's 60 cycle and as I like to listen to AM before I go to sleep I tend to listen at low volumes therefore the hum is more apparent at these times. Are there any mods or maybee wire positioning changes that may improve on this or is it just inherant to this type of transformerless radio design? My other question is, both of these amps have no input or power transformer and have 12 and 35 volt filaments is this what you guys mean when you say it's an ac/dc radio?? If this where a guitar amp which I work on all the time I would check the filter caps but I just put new filter caps in both radios although I used a 100uF instead of the 80uF 150 that I replaced and a 47 instead of a 50uF 150V. Thanx Brian

Hi Brian, Perhaps the hum level in your set is normal, often sets have slight residual hum that you can hear at low volume in quiet surroundings. It might also be worse due to acoustics. If the set is on a table top for example, it can act as a sounding board and accentuate certain frequencies, perhaps the hum. If you're in bed, mattress springs can also resonate and may be adding to the hum (you'd be surprised just how effective they can be at this). Don Black.

: Hello my RCA Victrola X624 is fixed thanx Renee and Denis! However, the filter caps have been replaced and like my other RCA Victrola 9Y5 it has a slight hum a little to loud for my liking I think it's 60 cycle and as I like to listen to AM before I go to sleep I tend to listen at low volumes therefore the hum is more apparent at these times. Are there any mods or maybee wire positioning changes that may improve on this or is it just inherant to this type of transformerless radio design? My other question is, both of these amps have no input or power transformer and have 12 and 35 volt filaments is this what you guys mean when you say it's an ac/dc radio?? If this where a guitar amp which I work on all the time I would check the filter caps but I just put new filter caps in both radios although I used a 100uF instead of the 80uF 150 that I replaced and a 47 instead of a 50uF 150V. Thanx Brian