[MissouriLarry]

Ok, now is time to post my first question.  I have a Philco 46-1213 that I am going to start working on here real shortly.  I have been studying the Schematic for the last few days.  I am completely new at reading them, but I have been doing a lot of research and have watched several videos.  They're starting to make more sense to me, but I have a long way to go.   My first task for this radio is to replace the crumbling 2 prong non-polarized plug.  I want to use a 3-wire cord, with an inline fuse.  My trouble with reading the Schematic is I don't understand which connection is the neutral wire.  I will attach a photo of my schematic.  How do you decide which leg is neutral so not to place the power on the chassis?

[GarySP]

Hello Larry. Replacement of the power cord is a priority, but not the first. All paper and electrolytic capacitors need replacement before introducing electricity to the mix. All resistors should also be tested, and all out-of-tolerance replaced. The Bakelite block in your picture has two filter caps that require safely caps when you rebuild it. Several tutorials are available here for rebuilding tips. There is no reason to install a three-pronged plug. Those safety caps provide your path to ground. Hope this helps. Take care, - Gary

[RodB]

Hi Larry,

Usually you'll want to attach the hot side of the power line cord to the power switch. That way when the switch is off there is no source of voltage other than the power switch. Looking at your schematic you have a situation where the line filter caps (75A and 75B) always have power on them when the power cord is plugged in. I always rewire them to the other side of the power switch so they only have power when the switch is on. BTW these caps should be replaced with Y2 safety caps.

[MissouriLarry]

Gary,
Thanks for the reply!  I have no intention of introducing any electric to my radio until I recap it.  I just wanted to pick a place to start, and I figured the cord was a good starting place.  My thoughts of a 3 wire were to have a ground on the chassis, but if that is not needed then I would still like to use a polarized 2-prong.  Still, I am confused how to choose which side of the terminal is the neutral and which is the load.  How does one distinguish from the schematic which is which?  I've read that the neutral often is on the switch side of these, but I am not sure.  I would like to learn how to decipher this from the schematic for future knowledge if anyone can help.

[MissouriLarry]

In the photo of my Chassis, I now have two wires marked "A" and "B", these are my power cord wires.  What I am trying to find out is which of these wires should be the neutral wire and which should be the power wire?  Looking at the schematic I cannot figure out which is which, and if you do know I would like to know how to figure this by the schematics.

[RodB]

You have to examine the connections to A and B to see which one matches the schematic. It appears there are two white wires on A. If one goes to the transformer and the other goes to the phono power plug then A is the neutral.

[MrFixr55]

Hi Larry,

Back when this set was built, they did not use polarized power plugs. Technically, your chassis is sitting at about 60V above ground due to the small current across the caps in the bakelite block, C100A and B. Like Rod B suggested, if a polarized or 2 wire cord is used, Hot goes to the terminal of C100 that leads to the power switch.

Although it is certainly safe to attach a 3 wire cable to a transformer powered chassis, in this modern- day world of computers, the Internet of Things, LED and CFL lights, computers, digital TVs, carrier current meter reading etc., using the power line ground as a ground for the antenna may introduce EMI noise.

[MissouriLarry]

RodB & MrFixr55,
Thank you both for the great replies at my questions, I appreciate the help very much.  As suggested, I think I will change directions and just use a 2-wire cord, but I intend to fuse it for safety.  Thanks to all who have made suggestions, they are greatly appreciated.  I have a lot to learn.

[radiorich]

Hello Larry,
Well, anyway I can contest about noisey grounds in my living room when I am using one outlet in my house and the porch light is on it causes issues in my radio .

Far as the Safety capacitor goes the normal value is .01 ufd

Sincerely Richard

[RodB]

Good idea on the fuse. These old transformers need extra protection.

[MrFixr55]

Hi Larry,

Great idea on the fuse!  Place in the line at the power switch.  Best between the cord and switch.  While not highly important on a transformer powered radio, important, it is a good idea to use a polarized power cord.  the larger pin (Neutral) goes to the side of the transformer that is not the switched side.  The smaller pin (Line) goes to the switch.

One concern is that you WILL get a bit of a "tickle" from the two 0.01 uF Y2 caps that run from Line (hot) and Neutral to the chassis.  This puts the chassis at half the line voltage, but at relatively low current.  Since the old caps can leak or short, the current may be rather high.  This is why we recommend the Y2 safety caps.  Your desire to use a grounded cord is laudable, but as others have stated, there is a lot of noise on the grounding system in the average house.  For sets with a long wire antenna and ground, where the ground end of the antenna coil is connected to the chassis, this can be an issue.  However, your set has a loop antenna and an FM Dipole, therefore using a 3 wire plug might not cause noise.  Try it both ways.  "Tack" on the 3 wire cord (black or brown is hot, blue or white is neutral and green or green / yellow is ground.  Plug in directly, then use a 3 pin to 2 pin adaptor used to allow the use of a 2 prong outlet on a 3 prong cord. (This device is often referred to as a gozinta, as in "this gozinta that").  Tape the ground lug that is supposed to connect to the outlet plate screw.  This will allow you to determine which way works better for you.