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Phico 70 resistors: red-yellow-yellow - Printable Version

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Phico 70 resistors: red-yellow-yellow - morzh - 02-16-2020

What I am not sure of if these follow the color convention or they don't.

Here's why: they (body-end-dot being RYY) supposed to be 240K which is what Steve's labels on his resistors show if you look in here:
https://www.ebay.com/itm/Reproduction-Dogbone-Resistors-For-Philco-70/293463010038?hash=item4453c22af6:g:~WAAAOSwTlddxEaB&redirect=mobile

However if looking here,
http://www.nostalgiaair.org/Resources/833/M0013833.htm

On page 1-18 in Resistor Data table they show 250,000 ohm.

But on the page 3-32 in the table 4 "resistor data" the same ones are shown as 330,000 ohm.

So.....which one is it?

RE: Phico 70 resistors: red-yellow-yellow - Steve Davis - 02-17-2020

It is not just the 240K, if you look at the parts list they show a couple of 50K, but in your chassis you will find 51K. In other Philco radios, 99Ks are used but, the parts list shows them as 100K. At any rate, we are talking about less than one percent difference.

Steve

RE: Phico 70 resistors: red-yellow-yellow - Steve Davis - 02-17-2020

I just looked at Ron's schematic in the Phourm Library   https://philcoradio.com/library/index.php/service-info/early-schematics/    and it shows 240K.

Steve

RE: Phico 70 resistors: red-yellow-yellow - RodB - 02-17-2020

Well gee, if you're going to have a standard why not use it? We all know RYY is 240k and sometimes a production run is short of the correct value. 250k is close enough! ! 330k looks like you can chalk one up for Riders or maybe even Philco.

Rod

RE: Phico 70 resistors: red-yellow-yellow - Chas - 02-17-2020

Now don't put my brains in the fire!

Long ago, in some publication on radio, I had read, that, the Philco production environment used a LOT of mercury lamp illumination. Because the light was so rich in UV, normal color codes could not be used. Thus, odd ball colors.

Given that dog bone resistor drift and production line changes did not always get recorded, we, see the resistors as they are, different.

Dog bones like paper caps are way beyond end of life. I abandoned using measured values of dog bones (re-paints). I found that they continue to drift from the current flow and even moderate heat, have gotten noisy too...

YMMV

Chas

RE: Phico 70 resistors: red-yellow-yellow - morzh - 02-17-2020

Believe it or not, most of the resistors in this Philco are within the tolerance.
But these two measure 360K in-circuit or so.

RE: Phico 70 resistors: red-yellow-yellow - Steve Davis - 02-17-2020

Quote:But on the page 3-32 in the table 4 "resistor data" the same ones are shown as 330,000 ohm.


3-32 table 4 is for the late version 70

The early Philcos used a proprietary resistor color code. Generally a solid body color and sometimes an end color. The Philco 20 used this system and probably was the last. The Philco 70 and later used the standard BED color code.

Steve

RE: Phico 70 resistors: red-yellow-yellow - Steve Davis - 02-17-2020

I just pulled out a couple of 70 chassis that I have and checked the resistance of the Red-Yellow-Yellow resistors. One of them they were pretty close at 245K give or take. The other was not so good, one was 410K and 418K.

Steve

RE: Phico 70 resistors: red-yellow-yellow - morzh - 02-18-2020

So, in 570 how do I know which version of the mentioned ones do I have? I have not found (in Riders or the compilation of it on Nostalgia) the chassis that would be exactly what I have. Either resistors do not agree or the backelite capacitors.

Also......if the rest of the resistors in my radio do use the standard color chart (say Green-black-red is 5.1K, and so do others) then I think indeed my Red-Yellow-Yellow are 240K.
They wouldn't mix the standard/non-standard ones, would they?

RE: Phico 70 resistors: red-yellow-yellow - Mike L - 02-18-2020

Morzh,

I don't know if this helps, but I found an old article in Philco News dated September 1931 page 12 that states: "Starting with the Model 46 and continuing in all future models, standard R.M.A. colors are being used to indicate the value of various resistors in Philco Receivers." It continues to list part numbers , color codes and resistor values. I cant up load the page right now. It clearly states that Red body, Yellow tip and Yellow dot is 240k, 1 watt P/N 3768. It also has the same color code for a 1/2 watt P/N 4410.