Have a 110volt 45-60 cycle ac/dc radio, is it safe to plug it in to 120 household ac, or should I get a converter to get the 110volts? Upon initially testing the old set I pluged it in and it did nothing but hum, it wasn't until I took it apart to test the capacitors that I discovered the model spec tag listing the volts, hope I didn't screw anything up.

Alex

It will be safe to operate off of the 120 volt AC line but I would change the electrolytic filter caps first. The hum is caused by these caps drying out over time. They can short and damage other parts of your radio.

While you are working on the radio, add a 100 watt light in series with the AC line. The light will act as a fuse and limit current to the radio if something shorts.

Norm

: Have a 110volt 45-60 cycle ac/dc radio, is it safe to plug it in to 120 household ac, or should I get a converter to get the 110volts? Upon initially testing the old set I pluged it in and it did nothing but hum, it wasn't until I took it apart to test the capacitors that I discovered the model spec tag listing the volts, hope I didn't screw anything up.

Norm, Bart,

Thanks! couple more questions, the majority of the caps are 0.5 mfd@200-400 volts, any problems with changing these to say .068mfd@200-400 volts or mayby even 1.0mfd@200-400volts. Also there is a big one with a single lead in and dual outs (10+10mfd@400volts), can I use two 10mfd@400volt caps inplace of this?

: Norm, Bart,

: Thanks! couple more questions, the majority of the caps are 0.5 mfd@200-400 volts, any problems with changing these to say .068mfd@200-400 volts or mayby even 1.0mfd@200-400volts. Also there is a big one with a single lead in and dual outs (10+10mfd@400volts), can I use two 10mfd@400volt caps inplace of this?

Use individual 450 volt caps for the dual 10 mf unit. .68 or 1 mf would be ok for .5 mf caps. The exact value isn't critical. Voltage ratings should be as high as or higher than the original caps.

Norm

: Norm, Bart,

: Thanks! couple more questions, the majority of the caps are 0.5 mfd@200-400 volts, any problems with changing these to say .068mfd@200-400 volts or mayby even 1.0mfd@200-400volts. Also there is a big one with a single lead in and dual outs (10+10mfd@400volts), can I use two 10mfd@400volt caps inplace of this?

Isn't that a bit unusual for the filter cap of a line-operated ac/dc set to be 450v? I'd think that the original would have been rated at 150v (replace with a 200v unit for today's slightly higher line voltages).

I wonder if the cap that's in there now was a replacement unit?

Dean

Agree with Dean, if this is an AC/DC radio the caps can be lower voltage. Modern ones would be rated 160 volts but the values wouldn't be 10 mfd, more like 30/50 mfd. If the dual 10 @ 400 volts is original the radio may have a power transformer and be AC only.

If the radio has a power transformer, you will need higher voltage filter caps.

Maybe I overlooked the radio model number?

Norm

: Isn't that a bit unusual for the filter cap of a line-operated ac/dc set to be 450v? I'd think that the original would have been rated at 150v (replace with a 200v unit for today's slightly higher line voltages).

: I wonder if the cap that's in there now was a replacement unit?

: Dean

the 10+10mfd@400v seems to be the original cap there was another cap rated at .1mfd@ 600v the majority of the others are .05mfd@200v, there is another mystery cap with no rating just a part number and 25-200 printed in the middle. It's a big cap close to 3inches. The model number on this set is a knight e10770, which has now developed other problems such as no sound, Norm has been nice enough to help me out on this, Thanks!

the 10+10mfd@400v seems to be the original cap there was another cap rated at .1mfd@ 600v the majority of the others are .05mfd@200v, there is another mystery cap with no rating just a part number and 25-200 printed in the middle. It's a big cap close to 3inches. The model number on this set is a knight e10770, which has now developed other problems such as no sound, Norm has been nice enough to help me out on this, Thanks!

Hi Alex,
Yes, it's safe to use 120V on a 110V radio. While you are replacing the filter caps you might want to check to see if a small resistor of 22 or 33 ohms is in line between them and the powrer rectifier tube. If not, put one in for protection from blowing the fine wires in the tube during the initial current surge at turn-on. This is especially true if you install capacitors larger (i.e. 47\47 or 80/47) than the 50/30 Mfd that were usually standard. The tube might survive the heavier surge for a while, but my experience is that it eventually takes its toll. Then you might have an intermittent power situation until the break in the tubes wire opens enough to cut the connection completely. The larger value of the pair feeds directly from the power tube. The larger capacitors will reduce the hum somewhat. While you are replacing the power caps, take a look around in there and see if there are any paper caps and replace any that you find. They get leaky with time and will ground the signal so that you hear nothing but the hum (as quiet as it may be) from the power supply.-Bart

: Have a 110volt 45-60 cycle ac/dc radio, is it safe to plug it in to 120 household ac, or should I get a converter to get the 110volts? Upon initially testing the old set I pluged it in and it did nothing but hum, it wasn't until I took it apart to test the capacitors that I discovered the model spec tag listing the volts, hope I didn't screw anything up.

I re-capped a GE five tube table top. It humms worse than ever. I did not replace the great big dual 50 mfd. Didn't have one handy. Not exactly a common item. I will buy one next time I do some mail order. Question, will all new caps make the remaining big one act worse if not replaced?

Scot

Scot

It could, the radio will be amplifing the hum more. Replace those 50 mf caps with individual 47 mf @ 160 volt caps.

Norm

: I re-capped a GE five tube table top. It humms worse than ever. I did not replace the great big dual 50 mfd. Didn't have one handy. Not exactly a common item. I will buy one next time I do some mail order. Question, will all new caps make the remaining big one act worse if not replaced?

: Scot