The PHILCO Phorum
AC plug replacement - Printable Version

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AC plug replacement - terrylett - 04-20-2019

Hello everyone -

I am finally getting around to working on a Philco 52-944 I had stored away and one thing irritates me right off the bat.
 
These radios have that AC power cord mounting that is attached to the back cover and provides a female connection to the 2-prong intake on the chassis rear which means the back cover has to stay secure (and this one doesn’t have the best attachments) or the power can disconnect while the radio is on.
 
Furthermore the AC cord itself is in tatters and I didn’t want to risk plugging it in. It has sloppy electrical tape patches in 2 spots and I need to replace it.
 
The issue is that since this is the original plug and is not polarized what is the best thing to do as far as replacing with a safe polarized plug and hopefully eliminating that 2-prong “thing” that is such a risk for disconnecting.
 
Any suggestions?
 
Thanks.

RE: AC plug replacement - morzh - 04-20-2019

This radio has one of the stupidest arrangemens where no matter what you do it's bad.

If you cannot touch the chassis then it doesn't matter much, especially considering it was unpolarized in the first place.

Now with polarized, if you route Neutral (wide) to the switch your chassis becomes hot (I didn't study the sch too close so I assume the GND symbol is chassis). Whch is bad.
Do the opposite and your chassis becomes hot when the radio is turned off.

So.....same thing, doesn't matter.

RE: AC plug replacement - Paul Philco322 - 04-20-2019

Find a cheater type cord and just go with it. 

Paul

RE: AC plug replacement - terrylett - 04-20-2019

Can you enlighten?

Not sure what you meant by "cheater">

RE: AC plug replacement - Radioroslyn - 04-20-2019

I can. Cheater cord is generic name a line cord w/ two pin female connector on one end. Mostly used on tv's and radios from the '50s and 60's. Was used as a interlock so that if you took the back cover off of a set it would disconnect the ac power from in. Some don't have the mounting tabs on each side to rivet them to the Masonite back board. Now days it used on a lot  portable sets but the size and spacing varies somewhat so all will not fit all sets.

RE: AC plug replacement - Paul Philco322 - 04-20-2019

Several styles, kinda like this............

https://www.ebay.com/i/123573904616?chn=ps

Paul

RE: AC plug replacement - terrylett - 04-20-2019

Ah.

I agree with Morzh about these AC setups. I've seen this arrangement on others too like RCAs. This is probably why I stuck the radio in the closet about a year ago and forgot about it.

One thing I was considering was to drill a hole in the chassis rear and running a polarized cord that way. I've done that with 2-3 other radios and everything worked out fine. Those were less complicated AM only sets however and easy to reroute the circuitry.

I want to solder the AC hot wire right to the back of the switch for one thing but I'm a bit overmatched when it comes to all the rest of the wiring.

The existing setup has both prongs of the AC input grounded to the same chassis lug. One of the connections branches off to the dial lamp in its journey.

I didn't want to start something and just destroy the set but I wish I never bought this thing.

RE: AC plug replacement - terrylett - 04-20-2019

Oh I see what you're talking about.

But then which side would end up being the hot side and without rewiring internally would it even matter?

RE: AC plug replacement - Jake Blake - 04-20-2019

(04-20-2019, 09:44 PM)terrylett Wrote:  I want to solder the AC hot wire right to the back of the switch for one thing but I'm a bit overmatched when it comes to all the rest of the wiring.

The existing setup has both prongs of the AC input grounded to the same chassis lug.

I'm trying to find  the schematic for this one. I see Nostalgiaair doesn't have it.  Where else? Icon_mad

Jake

RE: AC plug replacement - terrylett - 04-21-2019

I'm pretty sure I got the schematic from Riders.

I have drilled a hole in the chassis rear and I have a nice polarized AC plug on a 6' cord so what I will probably end up doing is to solder the hot wire from the newly inserted cord to the existing internal prong that has a connection to the switch and solder the neutral side to the other prong.

That would do the same thing that the existing attached plug mount does and it would mean that the back cover could come off and the radio would still play. With the original non-polarized plug you could flip the hot and neutral sides anyway so I'm not concerned with polarity - just in replacing that damaged original cord and insuring that the AC port attached to the back cover is defunct.

I'm confident that this is a "floating chassis" set anyway so as long as I put the chassis back into the case I should be able to test it. If it powers up OK then I can move on to the recapping and wrap everything up.

RE: AC plug replacement - mikethedruid - 04-21-2019

Were it my radio, I would check using an ohm meter to see which of the two "prongs" was connected to the chassis. I would connect this prong to the wide blade lead, (neutral, or 'gounded') and the lead from the narrower blade (hot) to the "prong that did not connect to the chassis. This would ensure that the chassis was connected to the grounded side of AC. In U. S. electrical distribution, for the 120V receptacles, the wider blade is supposed to be at the same potential as the ground (U shaped) blade. They both connect back to the ground bar at the fuse or breaker box, the wide blade through the white wire in the house wiring to the receptacle, the U shaped blade through the bare, or the green wire in the house wiring.

RE: AC plug replacement - terrylett - 04-21-2019

Understood.

The thing is that they both connect to the chassis. As a matter of fact they both connect to the exact same chassis lug.

RE: AC plug replacement - Jake Blake - 04-21-2019

Isn't there a schematic available online anywhere?

I've put a polarized cord like that on the 48-1256, and I took care to keep the neutral to the side closest to chassis ground. But more and more, I'm developing the mindset ( like many manufacturers), Icon_idea that anything with a metal case ( or chassis) should get a 3-conductor grounding power cord.  I put one on the 89-B years ago. I feel the safety it affords trumps a rigid, original restoration value.  And in the case of the 89B and the 39-6 C I, it nicely eliminates the need to have a separate grounding wire coming out separately,  out the back of the set .

RE: AC plug replacement - terrylett - 04-21-2019

Jeff -

My mistake - I didn't get it from Riders I got it from this source:

Beitman Radio Diagrams Vol. 12, 1952

What I did was google "Philco 52-944 radio" which has a link to the RadioMuseum. In that webpage it mentions Beitman's as a source of data.

RadioMuseum

RE: AC plug replacement - terrylett - 04-21-2019

Oh and you can actually download the schematic from that site itself.