Ok I have asked this question before..and I can not remember...(This time I am going to write it down LOL) I am currently working on a 1936 Fairbanks Morse chasssis model 72. The line cord goes to switch and other end is connected to transformer and a large mica cap (mica cap is in turn connected to chasis) Chassis is ground on this set. MY QUESTION IS...Does the fat prong of polarized cord go to transformer and "thin" prong go to switch..? I would appreciate it if someone could explain this to me..I know you do this different in other types of sets. For the most part I collect late 1920-45 AC sets. When doing line cord I wana be sure I am doing it right so when i touch chassis I won't get a lethal shock LOL... THANK FOR ANY HELP>>>>

:Ok I have asked this question before..and I can not remember...(This time I am going to write it down LOL) I am currently working on a 1936 Fairbanks Morse chasssis model 72. The line cord goes to switch and other end is connected to transformer and a large mica cap (mica cap is in turn connected to chasis) Chassis is ground on this set. MY QUESTION IS...Does the fat prong of polarized cord go to transformer and "thin" prong go to switch..? I would appreciate it if someone could explain this to me..I know you do this different in other types of sets. For the most part I collect late 1920-45 AC sets. When doing line cord I wana be sure I am doing it right so when i touch chassis I won't get a lethal shock LOL... THANK FOR ANY HELP>>>>

The fat prong, the cold side of the power goes to the switch. This is preferred because the switch also has the volume control. A high AC voltage on the switch when turned on can couple to the sensitive signals in the volume control, resulting in hum.

Best Regards,

Bill Grimm

Ok I am confused..I was told small prong to switch...hmmm When is this done then?

::Ok I have asked this question before..and I can not remember...(This time I am going to write it down LOL) I am currently working on a 1936 Fairbanks Morse chasssis model 72. The line cord goes to switch and other end is connected to transformer and a large mica cap (mica cap is in turn connected to chasis) Chassis is ground on this set. MY QUESTION IS...Does the fat prong of polarized cord go to transformer and "thin" prong go to switch..? I would appreciate it if someone could explain this to me..I know you do this different in other types of sets. For the most part I collect late 1920-45 AC sets. When doing line cord I wana be sure I am doing it right so when i touch chassis I won't get a lethal shock LOL... THANK FOR ANY HELP>>>>
:
:The fat prong, the cold side of the power goes to the switch. This is preferred because the switch also has the volume control. A high AC voltage on the switch when turned on can couple to the sensitive signals in the volume control, resulting in hum.
:
:Best Regards,
:
:Bill Grimm

:Ok I am confused..I was told small prong to switch...hmmm When is this done then?
:
:
:::Ok I have asked this question before..and I can not remember...(This time I am going to write it down LOL) I am currently working on a 1936 Fairbanks Morse chasssis model 72. The line cord goes to switch and other end is connected to transformer and a large mica cap (mica cap is in turn connected to chasis) Chassis is ground on this set. MY QUESTION IS...Does the fat prong of polarized cord go to transformer and "thin" prong go to switch..? I would appreciate it if someone could explain this to me..I know you do this different in other types of sets. For the most part I collect late 1920-45 AC sets. When doing line cord I wana be sure I am doing it right so when i touch chassis I won't get a lethal shock LOL... THANK FOR ANY HELP>>>>
::
::The fat prong, the cold side of the power goes to the switch. This is preferred because the switch also has the volume control. A high AC voltage on the switch when turned on can couple to the sensitive signals in the volume control, resulting in hum.
::
::Best Regards,
::
::Bill Grimm

Every now and then it seems that people on this site get all worked up over the shock hazards presented by old radios. Guess what? These sets were made by the zillions and it seems that we're all still here. Those of us born after they were made are here because our parents survived them. Can you get shocked with one of these? Yes. Is is likely to do you in? No. That is if you are smart enough not to try to work on one while standing in water barefoot or use one in the bathtub. In other words use some common sense. Oh, the other thing you also should avoid is working on one while standing on a ladder. The shock might make you fall and go boom. Lighten up.

::Ok I am confused..I was told small prong to switch...hmmm When is this done then?
::
::
::::Ok I have asked this question before..and I can not remember...(This time I am going to write it down LOL) I am currently working on a 1936 Fairbanks Morse chasssis model 72. The line cord goes to switch and other end is connected to transformer and a large mica cap (mica cap is in turn connected to chasis) Chassis is ground on this set. MY QUESTION IS...Does the fat prong of polarized cord go to transformer and "thin" prong go to switch..? I would appreciate it if someone could explain this to me..I know you do this different in other types of sets. For the most part I collect late 1920-45 AC sets. When doing line cord I wana be sure I am doing it right so when i touch chassis I won't get a lethal shock LOL... THANK FOR ANY HELP>>>>
:::
:::The fat prong, the cold side of the power goes to the switch. This is preferred because the switch also has the volume control. A high AC voltage on the switch when turned on can couple to the sensitive signals in the volume control, resulting in hum.
:::
:::Best Regards,
:::
:::Bill Grimm

Bill, thanks. DadGummit, I've tended to put the switch on the hot side - that way, when the switch is OFF, most of the chassis wiring is de-energized. I hadn't thought about hum.
Doug
:
:The fat prong, the cold side of the power goes to the switch. This is preferred because the switch also has the volume control. A high AC voltage on the switch when turned on can couple to the sensitive signals in the volume control, resulting in hum.
:
:Best Regards,
:
:Bill Grimm

Doesn't the same current that flows in the "hot" lead ultimately end up on the "neutral" as well? I am thinking the hum would be the same regardless since it is a closed loop system. Maybe I am wrong.

:Bill, thanks. DadGummit, I've tended to put the switch on the hot side - that way, when the switch is OFF, most of the chassis wiring is de-energized. I hadn't thought about hum.
:Doug
::
::The fat prong, the cold side of the power goes to the switch. This is preferred because the switch also has the volume control. A high AC voltage on the switch when turned on can couple to the sensitive signals in the volume control, resulting in hum.
::
::Best Regards,
::
::Bill Grimm

Hi John,
You are right, the same current flows to the ground or cold side. It is voltage potential that is the issue.
If the cold side is switched, the switch is at an electrical potential similar to the potentiometer, near zero with respect to ground. For this reason no hum will be induces into the volume control circuitry.
If the hot side is switched, then a 110 volt AC potential exists with the volume control, giving ample opportunity for hum to be induced.

Best Regards,

Bill Grimm

::Ok I have asked this question before..and I can not remember...(This time I am going to write it down LOL) I am currently working on a 1936 Fairbanks Morse chasssis model 72. The line cord goes to switch and other end is connected to transformer and a large mica cap (mica cap is in turn connected to chasis) Chassis is ground on this set. MY QUESTION IS...Does the fat prong of polarized cord go to transformer and "thin" prong go to switch..? I would appreciate it if someone could explain this to me..I know you do this different in other types of sets. For the most part I collect late 1920-45 AC sets. When doing line cord I wana be sure I am doing it right so when i touch chassis I won't get a lethal shock LOL... THANK FOR ANY HELP>>>>
:
:The fat prong, the cold side of the power goes to the switch. This is preferred because the switch also has the volume control. A high AC voltage on the switch when turned on can couple to the sensitive signals in the volume control, resulting in hum.
:
:Best Regards,
:
:Bill Grimm

I don't think 1940 would be a cutoff - as long as the power switch is on the volume control.

If the hum is acceptable, I wouldn't change it for radios that you've already restored.

The hum that would result from coupling to the power switch should be 60-Hz hum, not the 120-Hz hum that is typical of full-wave rectifiers use on AC sets.
Doug

I wouldn'y worry about AC coupling from line or neutral, since the same current flows in both legs when the circuit is completed thru the switch. In addition, the volume control is typically isolated inside a metal can with the switch attached on the rear. On the other hand, I wouldn't run AC line or neutral in close proximity parallel to any audio wires. Most times it helps to twist AC line and neutral or parallel filament strings together, reducing any radiation to a minimum.

marv

::Ok I have asked this question before..and I can not remember...(This time I am going to write it down LOL) I am currently working on a 1936 Fairbanks Morse chasssis model 72. The line cord goes to switch and other end is connected to transformer and a large mica cap (mica cap is in turn connected to chasis) Chassis is ground on this set. MY QUESTION IS...Does the fat prong of polarized cord go to transformer and "thin" prong go to switch..? I would appreciate it if someone could explain this to me..I know you do this different in other types of sets. For the most part I collect late 1920-45 AC sets. When doing line cord I wana be sure I am doing it right so when i touch chassis I won't get a lethal shock LOL... THANK FOR ANY HELP>>>>
:
:The fat prong, the cold side of the power goes to the switch. This is preferred because the switch also has the volume control. A high AC voltage on the switch when turned on can couple to the sensitive signals in the volume control, resulting in hum.
:
:Best Regards,
:
:Bill Grimm

:Ok I have asked this question before..and I can not remember...(This time I am going to write it down LOL) I am currently working on a 1936 Fairbanks Morse chasssis model 72. The line cord goes to switch and other end is connected to transformer and a large mica cap (mica cap is in turn connected to chasis) Chassis is ground on this set. MY QUESTION IS...Does the fat prong of polarized cord go to transformer and "thin" prong go to switch..? I would appreciate it if someone could explain this to me..I know you do this different in other types of sets. For the most part I collect late 1920-45 AC sets. When doing line cord I wana be sure I am doing it right so when i touch chassis I won't get a lethal shock LOL... THANK FOR ANY HELP>>>>

We should remember that polarized plugs weren't around yet when most of these radios were built.
There was a 50/50 chance that when the set was plugged in back then that the hot side of the line would end up on the power switch.
The manufacturers didn't think it was a significant detriment to the set's performance then. I'm not sure it is today.

::Ok I have asked this question before..and I can not remember...(This time I am going to write it down LOL) I am currently working on a 1936 Fairbanks Morse chasssis model 72. The line cord goes to switch and other end is connected to transformer and a large mica cap (mica cap is in turn connected to chasis) Chassis is ground on this set. MY QUESTION IS...Does the fat prong of polarized cord go to transformer and "thin" prong go to switch..? I would appreciate it if someone could explain this to me..I know you do this different in other types of sets. For the most part I collect late 1920-45 AC sets. When doing line cord I wana be sure I am doing it right so when i touch chassis I won't get a lethal shock LOL... THANK FOR ANY HELP>>>>
:
:We should remember that polarized plugs weren't around yet when most of these radios were built.
:There was a 50/50 chance that when the set was plugged in back then that the hot side of the line would end up on the power switch.
:The manufacturers didn't think it was a significant detriment to the set's performance then. I'm not sure it is today.
:
:rember the days of non polarized plugs?? i had an old tape recoder with tubes. plug it in one way it hummed. turn the plug the other way it was fine.