I understand that AC/DC radios inherently have a risk of being "hot" when their plugged in whether the switch is on or off. The blades on the plugs that came with these radios are the same dimension since polarization was not an issue at the time so the chances of power going through the chasis is 50/50 with an "authentic" replacement cord. Even if I know which side was "hot" Id like to rewire the radio to lessen those odds.

To correct this issue I read about a procedure that would insure a cold chassis by removing the AC power to the chassis and placing it on the switch. The neutral wire would ground to the chassis. This would require a polarized plug. I have the steps available but Id like some input before I do this.

Here is a link about the S-38 line. Most AA5 radios use the same hot chassis power supply. You can do this to your radio.

http://www.the-s38-guy.com/Page_2.html

If this is in reference to the Zenith 6D015 about which you earlier posted, it does not actually have a "hot chassis". The metal chassis of this radio is electrically segregated from either side of the AC input line. The two "grounds" (B- and Chassis) are connected RF-wise by a capacitor (C5); if this capacitor were to short out, THEN you could have a "hot chassis" but otherwise, no.

Some other AC/DC radios did use the metal chassis as a tie point for one of the AC line sides. These would be true "hot chassis" sets. In this case, it would be advisable to retrofit the set with a polarized-plug cordset and connect the wider blade plug wire (neutral) to the chassis. This of course assumes that your house was wired according to code so that "neutral" really is "neutral" (instead of "hot").

:If this is in reference to the Zenith 6D015 about which you earlier posted, it does not actually have a "hot chassis". The metal chassis of this radio is electrically segregated from either side of the AC input line. The two "grounds" (B- and Chassis) are connected RF-wise by a capacitor (C5); if this capacitor were to short out, THEN you could have a "hot chassis" but otherwise, no.
:
:Some other AC/DC radios did use the metal chassis as a tie point for one of the AC line sides. These would be true "hot chassis" sets. In this case, it would be advisable to retrofit the set with a polarized-plug cordset and connect the wider blade plug wire (neutral) to the chassis. This of course assumes that your house was wired according to code so that "neutral" really is "neutral" (instead of "hot").
:
To CV: Thank you for the details. Most forums don't seem to explain the reasoning as much as they change the subject. You just saved me a lot of trouble with the Zenith. I understand the issue with the C-5. Some forum input calls them "death caps" for amplifiers tied to electric guitars. I have an almost completely insulated radio with plastic chassis mounts so if the cap fails, (given the polarized plug), the radio wont work. The outlets in the house were tested by me when I moved into the house 10 years ago.

To Warren and CV: The Hallicrafters 5R10 I just finished with is the other issue. I'm told its a predecessor to the Hallicrafters S-38 model and runs the same risk if the chassis grommets fail. Metal case and all. Not to mention that chrome plate I have to touch just to change the settings. I would personally feel better with warrens suggestion regarding the S-38.

"To Warren and CV: The Hallicrafters 5R10 I just finished with is the other issue. I'm told its a predecessor to the Hallicrafters S-38 model and runs the same risk if the chassis grommets fail. Metal case and all. Not to mention that chrome plate I have to touch just to change the settings. I would personally feel better with warrens suggestion regarding the S-38"

The 5R10 was a contemporary model to the S-38C. They have similar chasses but the 5R10 was a "stripped down" model lacking some of the S-38C's features such as BFO and T/R mode switch. The 5R10, like the S-38, had a "hot chassis" which would be a candidate for upgrading with a polarized cordset that connects the metal chassis (not the case) to the house neutral line. An external isolation transformer would be another approach. Either approach is probably overkill unless the set is to be operated in a damp environment(!) but I suppose that there is something to be said for "peace of mind".

It would be possible to go "whole hog" with the 5R10 (or S-38) and use a three-wire cordset. The "hot" lead would be the one that goes to the set's on-off switch, the neutral lead would go to the set's chassis, and the ground lead would go to the set's metal case. Installing a GFI at the outlet where the set is used would make the thing nearly bulletproof with respect to user safety. But, as I said, this seems like overkill unless the set is going to be operated in extreme conditions (such as outdoors or in a steamy kitchen or bathroom).

:It would be possible to go "whole hog" with the 5R10 (or S-38) and use a three-wire cordset. The "hot" lead would be the one that goes to the set's on-off switch, the neutral lead would go to the set's chassis, and the ground lead would go to the set's metal case. Installing a GFI at the outlet where the set is used would make the thing nearly bulletproof with respect to user safety. But, as I said, this seems like overkill unless the set is going to be operated in extreme conditions (such as outdoors or in a steamy kitchen or bathroom).
:I dont plan to listen to radio romania in the shower, but since the radio is belly up its a good time to rewire it so the hot AC is on the switch instead of the chassis. I would think going whole hog would be to rubber coat the whole thing after the GFI, and the three wire ground. Or would that be just ridiculous?

:I understand that AC/DC radios inherently have a risk of being "hot" when their plugged in whether the switch is on or off. The blades on the plugs that came with these radios are the same dimension since polarization was not an issue at the time so the chances of power going through the chasis is 50/50 with an "authentic" replacement cord. Even if I know which side was "hot" Id like to rewire the radio to lessen those odds.
:
:To correct this issue I read about a procedure that would insure a cold chassis by removing the AC power to the chassis and placing it on the switch. The neutral wire would ground to the chassis. This would require a polarized plug. I have the steps available but Id like some input before I do this.
:
: Here is some info. for you. go on to the website --fun with tubes,angelfire,then go down to "What Is Ground?. This sub posting will give you everything you need to know about grounds & THEN SOME! If this site can't help you understand grounds better, I don't believe anything else can. I have used this site before & it really has helped me get a good understanding of the hows & whys of receiver operation. I love this site. I said it before "a person could get a good electronics education here".Joke: without going to electronics school. I am kinda new to electronics. When I have a problem I go back through the months to see if I can learn anything about my current situation. Lots of fun! I know house wiring as I learned when I was 10 years old how to wire up a house. (And electric train hook-ups). But electronics is way different! Different colored wires have different meanings. Electronics & electricity are totally different.
:

Usually this would require re-wiring the power switch so it switches the Hot side of the line, not the chassis side and then reconnect it to the narrow side of the plug.

Note: if you want additional protection, you can run the radio using an isolation transformer. Using a GFCI outlet or plug (similar to what hair dryers have) would also provide additional protection against shock.

:I understand that AC/DC radios inherently have a risk of being "hot" when their plugged in whether the switch is on or off. The blades on the plugs that came with these radios are the same dimension since polarization was not an issue at the time so the chances of power going through the chasis is 50/50 with an "authentic" replacement cord. Even if I know which side was "hot" Id like to rewire the radio to lessen those odds.
:
:To correct this issue I read about a procedure that would insure a cold chassis by removing the AC power to the chassis and placing it on the switch. The neutral wire would ground to the chassis. This would require a polarized plug. I have the steps available but Id like some input before I do this.
:
:
:

:Usually this would require re-wiring the power switch so it switches the Hot side of the line, not the chassis side and then reconnect it to the narrow side of the plug.
:
:Note: if you want additional protection, you can run the radio using an isolation transformer. Using a GFCI outlet or plug (similar to what hair dryers have) would also provide additional protection against shock.
:
::I understand that AC/DC radios inherently have a risk of being "hot" when their plugged in whether the switch is on or off. The blades on the plugs that came with these radios are the same dimension since polarization was not an issue at the time so the chances of power going through the chasis is 50/50 with an "authentic" replacement cord. Even if I know which side was "hot" Id like to rewire the radio to lessen those odds.
::
::To correct this issue I read about a procedure that would insure a cold chassis by removing the AC power to the chassis and placing it on the switch. The neutral wire would ground to the chassis. This would require a polarized plug. I have the steps available but Id like some input before I do this.
::
::
::Problem solved. I used the procedure outlined by Chris 108 in "the antique radio forums". Its similar to at least three others Ive studied. Since the outlet the radio plugs into is correctly oriented I felt safe using it. The chassis is now cold. Here is the forum web page if anyone is interested. If in doubt, let someone else do it. Spend a few bucks and save a lot of grief.

http://www.antiqueradios.com/forums/viewtopic.php?f=6&t=37924&sid=c95baf0bccba72a79bc277a033ef497c&start=20

:

Hi

I've suggested this different times but it leads to another problem. Low level audio signals are on the volume control. If the hot side is switched this leaves 120 volts 60 cycle on the switch. Being close to audio this can give some 60 cycle hum.

Norm

::Usually this would require re-wiring the power switch so it switches the Hot side of the line, not the chassis side and then reconnect it to the narrow side of the plug.
::
::Note: if you want additional protection, you can run the radio using an isolation transformer. Using a GFCI outlet or plug (similar to what hair dryers have) would also provide additional protection against shock.
::
:::I understand that AC/DC radios inherently have a risk of being "hot" when their plugged in whether the switch is on or off. The blades on the plugs that came with these radios are the same dimension since polarization was not an issue at the time so the chances of power going through the chasis is 50/50 with an "authentic" replacement cord. Even if I know which side was "hot" Id like to rewire the radio to lessen those odds.
:::
:::To correct this issue I read about a procedure that would insure a cold chassis by removing the AC power to the chassis and placing it on the switch. The neutral wire would ground to the chassis. This would require a polarized plug. I have the steps available but Id like some input before I do this.
:::
:::
:::Problem solved. I used the procedure outlined by Chris 108 in "the antique radio forums". Its similar to at least three others Ive studied. Since the outlet the radio plugs into is correctly oriented I felt safe using it. The chassis is now cold. Here is the forum web page if anyone is interested. If in doubt, let someone else do it. Spend a few bucks and save a lot of grief.
:
:http://www.antiqueradios.com/forums/viewtopic.php?f=6&t=37924&sid=c95baf0bccba72a79bc277a033ef497c&start=20
:
:
::
:
:

I had a Zenith set that had been re-wired to have the switch in the hot lead and it did indeed introduce some hum. In this case the control body was isolated from the chassis. An 0.05 cap from the control body to the chassis eliminated the hum.

:Hi
:
: I've suggested this different times but it leads to another problem. Low level audio signals are on the volume control. If the hot side is switched this leaves 120 volts 60 cycle on the switch. Being close to audio this can give some 60 cycle hum.
:
: Norm

:I had a Zenith set that had been re-wired to have the switch in the hot lead and it did indeed introduce some hum. In this case the control body was isolated from the chassis. An 0.05 cap from the control body to the chassis eliminated the hum.
:
:
::Hi
::
:: I've suggested this different times but it leads to another problem. Low level audio signals are on the volume control. If the hot side is switched this leaves 120 volts 60 cycle on the switch. Being close to audio this can give some 60 cycle hum.
::
:: Norm
:
:Sorry about this late response. About the hum generated when the AC hot side of the power cord is directly connected to the power switch. I learned that "dressing" the power line away from any audio tube or connection from the audio portion of the switch limits the hum. I routed the power cable around the chassis instead of feeding it in between tubes. The hum is only apparent in between stations and seems to disappear when a station comes in.

"... The hum is only apparent in between stations and seems to disappear when a station comes in."

That's probably RF-borne hum coming in the set via the antenna. When you tune in a station, AVC reduces sensitivity of the front end and suppresses the low-level hum.

:"... The hum is only apparent in between stations and seems to disappear when a station comes in."
:
:That's probably RF-borne hum coming in the set via the antenna. When you tune in a station, AVC reduces sensitivity of the front end and suppresses the low-level hum.
:
Thank you for the information. Before I rewired for a cold chassis I was under the impression the noise would be intolerable. It gives the set some character.

:I understand that AC/DC radios inherently have a risk of being "hot" when their plugged in whether the switch is on or off. The blades on the plugs that came with these radios are the same dimension since polarization was not an issue at the time so the chances of power going through the chasis is 50/50 with an "authentic" replacement cord. Even if I know which side was "hot" Id like to rewire the radio to lessen those odds.
:Don't bet your life that the wall socket is wired correctly. Many are not, especially in older homes.
:To correct this issue I read about a procedure that would insure a cold chassis by removing the AC power to the chassis and placing it on the switch. The neutral wire would ground to the chassis. This would require a polarized plug. I have the steps available but Id like some input before I do this.
:
:
: