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To re-wire or not to re-wire.... - Printable Version

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To re-wire or not to re-wire.... - Greenhorn - 09-08-2017

I’m just curious, is there a consensus here among electronic restorers as to the re-wiring of hot chassis radios?
Do you always do it, never do it, or does it depend? What about hum? Thanks in advance.

Kelly

RE: To re-wire or not to re-wire.... - WallaceRoger - 09-08-2017

If the old wires (and their housings) are in decent shape, I leave them.

In the case of a Truetone I've slowly been working on for a couple months, half of the wiring was the old timey cloth covered stuff (which was fine), and half was covered in rubber, which was all crumbling. I replaced the crumbly stuff and left it at that. The old cloth covered stuff seems to last just about forever.

RE: To re-wire or not to re-wire.... - morzh - 09-08-2017

"Hot chassis" or, I'd rather call them AC/DC radios, typically AA5 or sometimes 4 or 6-tube jobs, were made from 30-s all the way into 50-s and so used different wires. I treat them on the individual basis, and not as a group. If you see the wiring is crumbling, then rewire; if not - leave it be.

RE: To re-wire or not to re-wire.... - Radioroslyn - 09-08-2017

+1
I rarely replace anything that isn't rubber. The old cloth cover wire I'm just careful not to flex it much. You can get yourself in to a bit of trouble doing a full rewire job. You have to pay attention to the layout, it's not too awfully hard to break off terminals when removing the old wiring which can make relatively simple job a headache.
What I do is replace the rotten pieces and go though the HV wiring and replace those too. Had one not too long that the HV wiring looked good but after some usage a section went up in smoke.

RE: To re-wire or not to re-wire.... - Greenhorn - 09-08-2017

I apologize for my poorly worded post and I appreciate the replies. What I was asking about was re-wiring the line cord, conecting the hot side to the switch and the neutral to the chassis and installing a polarized plug.
Thanks again.

RE: To re-wire or not to re-wire.... - morzh - 09-08-2017

Ahem...ok, now that we know... Icon_smile

my approach: if the cord is pliable, and no fraying, leave it. If it is ripped, or rigid, or both - then change it. If the original plug is good, though non polarized, leave it, if cracked - change.
Many people change the power dissipating cords. I think if good, which I just witnessed, leave it be, though for Kirk right now I disconnected the resistive part and put in capacitors, since that was the order Icon_smile

RE: To re-wire or not to re-wire.... - robsradioactive - 09-08-2017

If there is exposed chassis, I change to a polarized cord and run the hot wire to the switch and then back to the rectifier tube. I run this loop side by side and twist the wires together to minimize magnetic radiation. I try to run them around the corners of the chassis away from any audio tubes. I have never had a hum issue this way. Any line bypass caps get Y2 safety caps.
Rob

RE: To re-wire or not to re-wire.... - Arran - 09-10-2017

What I call a "Hot Chassis" set is an AC/DC radio where one side of the power line is connected directly to the sheet metal of the chassis, some companies did this because it was a cheap way to build, but most did not after the late 1930s.
The other way AC/DC sets are wired, and in fact are usually wired, is to have the B- independently wired and isolated from the chassis, with a capacitor and a resistor coupling the chassis to the B- wiring for RF shielding. Some call these "floating chassis" sets and this was how Philco, and RCA, usually wired their AC/DC model radios, brand Z less so.
  In my opinion rewiring the power cord with a polarized plug is a waste of time, almost invariably AC/DC sets, were designed so that the user would be insulated from the chassis under normal circumstances through an insulated cabinet, knobs, and a cardboard back. This is especially true when it comes to the floating chassis sets, they were designed to be as safe as they could be given the technology of the time in which they were built, later ones even had a safety interlock to stop people from poking around inside with the power cord connected.
 Now when it comes to the true "Hot Chassis" sets, yes they can be rewired to make them safer, I was attempting to do just that with one radio that had hacked up wiring underneath by running independent B- wiring from pin to pin, tube socket to tube socket, which was rather time consuming. I did find out a better way to do it though, I have a Belmont built Airline radio from 1949-50 where they ran a 6'' length of bare 16 gauge wire as a bus bar down the middle of the chassis, and connected anything that needed an electrical ground to it, I may try this trick on another set. The advantage to doing this is it curtails the likelihood of ending up with a dead short across the power line from something like a frayed antenna wire, not to mention reducing the shock hazard which is much higher when every piece of metal on the chassis is basically live.
Regards
Arran

RE: To re-wire or not to re-wire.... - Greenhorn - 09-11-2017

Thanks to All for the information and education, I can always use it. Icon_thumbup

RE: To re-wire or not to re-wire.... - byoungblood - 10-25-2017

I'm in the process of bringing a 42-1008 back to life, and I've had to replace almost all of the rubber insulated wire in it. Much of it just crumbled from being moved at all, some if you looked at it the wrong way it would crumble. Seems the yellow, red, and orange colored wire was the worst, the black and green ones were still relatively pliable after 75 years. Maybe whatever was used to pigment those particular colors is what made some of them become more brittle than others.