[Robbie Roberts]

Can anyone tell me what the wire colors should be within the chassis of a 37-650? Is there a set color code array for these radios? Mine have mostly faded to an almost uniform brown color at this point, and it makes replacing them difficult when I choose to do so. I have 4 Philcos to rebuild, and would like to get the colors right... The schematics are almost useless on that point- only certain items have colors listed... Wish I had a wiring diagram with wire lengths and colors listed...

Thanks-
Scott

[Bill Hutchinson]

Scott,

This may or may not be the answer you want to hear, but in the long run it probably doesn't matter much. For the majority of the wiring, I'd suggest 18 gauge wire, probably stranded. But since it's under the chassis and not moving around, solid wire would be OK, but not as easy to work with. Also, it's quite likely that much of the wiring is still in pretty good shape, as this radio predates the use of rubber coated wire. That was the case with mine, and I ended up only replacing a handful of wires. I'm a great believer in not making more work for myself than I have to.

Also, since it's underneath the chassis, it's also another reason why it wouldn't matter a lot what the colors are. But what you might want to do, just as a suggestion, would be use red for B+, black for ground, yellow for filaments, green for audio, and so on.

Again, it's yours, and you can set a standard for what you feel comfortable with. Your mileage may vary.

Chuck might have some specific data regarding this topic. I'm enjoying your updates on the 37-650, which is one of my personal favorites. Keep the updates coming!

Bill

[Chuck Schwark]

From the May, 1934 issue of the Philco Serviceman, page 4:

COLOR CODE FOR PHILCO WIRING

Philco has adopted the standard R.M.S. colde code as employed by various other radio manufacturers.
This coloring of wires is held wherever possible, and there are only a very few exceptions where the
standard coloring is not used.
The chart below indicates the various colors of wires and the types of circuits in which these wires are used:
__________________________________________________

RED . . . . . . . . . Filaments and odd wires

BROWN . . . . . . . Cathodes and grounds

WHITE . . . . . . . . B+ and screens of output pentodes

WHITE w/BLACK tracer
and/or
BLACK w/WHITE tracer . . . . Plates

GREEN . . . . . . . . Grids and screen grids
__________________________________________________

This may seem like a limited selection, but remember, this is 1934 and manufacturing standards are still being formed, hashed out and adopted among the many, many radio manufacturers of the day.

Every manufacturer's Engineering Department had the "not-invented-here" attitude to overcome as well when the industry was trying to standardize things.

[Ron Ramirez]

Not to mention the lighting used in Philco's factory at the time, which caused certain colors to look wrong.

[Chuck Schwark]

Hey, yeah.

Forgot about that Ron. True, true.

[Guest]

Ron or Chuck..what color did they use for ground or cathode? Really..brown??The colors you mention seem odd now, but they had to start somewhere. Guess I'm just used to the RMA codes... White as the "hot wire"?? Trouble with that is that white doesn't STAY white. Don't mistake a white wire for brown.. ZZZZZT!! The refined and final RMA code makes more sense--thankfully!

[Bill Hutchinson]

Chuck,

Thanks for the response. I was pretty sure there was a standardized wire layout used, but as you could probably tell from my reply, I'll tend to use what I have on hand to do the job.

But at least I try to follow the schematics to the letter.

Thanks for posting the info, and Merry Christmas to everyone on the Phorum.

Bill

[Robbie Roberts]

So, what RMA code version was in effect in 1937, 39, 41?

Scott

[Chuck Schwark]

My guess that this "loose" standard was followed, more or less, up to the war. Military contracts may have had a hand in really getting everybody on the same page, as far as electronic construction and manufacturing practices are concerned.

There were different wire color codes for various leaded components already in effect for various types of transformers and speakers, and it's possible that this code took over, or was augmented. Just speculation here....