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 dog bone resistors

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confused1



Join date : 2014-05-25

PostSubject: dog bone resistors   2014-05-25, 4:25 pm

I have a Philco model #19 of which looks to be a mix of two other designs in the #19 models, according to the schematics.
The real question is how does one know how to read the color codes on the dog bone resistors? I read that the main body color is "A" the end color is "B" and the dot or swatch of color on the main body is "D"...easy enough. what throws me for a loop is the two color ones. I have many in the philco that are two color with the siler or solerable caps on both ends. Do you count that as grey on the color chart?
I can kinda tell that some of them are out of tolerance but am  not sure....HELP!!!!


Last edited by confused1 on 2014-05-25, 4:31 pm; edited 1 time in total (Reason for editing : forgot to put main topic worg)
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Cliff Jones
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Join date : 2010-11-22

PostSubject: Re: dog bone resistors   2014-05-26, 11:32 pm

Are you saying there are only two colors? Body and tip or body and center dot?

It is read body first significant digit.
Tip (or End) second significant digit.
Center dot is Multiplier
If there is no center dot then the multiplier is the same as the body.
As far as the end color silver will try and find out. None of the resistors listed in code 128 had silver or gray on the tips so that was just conductive paint I guess.
Here is a schematic with colors listed
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Yes grey is a normal color
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I will need to know which resistor you are questioning, what are the connection points?
There were several factory modifications to the model 19. So It would help to know if it is a table top or console.

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confused1



Join date : 2014-05-25

PostSubject: Re: dog bone resistors   2014-05-27, 7:13 am

Hello Cliff
Some of the resistors have a half color design. Half red and half white with lead ends. some are all orange with a red tip. As far as I can see, there is one that is all white with the lead tips. There is one that I tried to read that turned out to be 93mohms. I'm sure I calculated that one wrong.Those are the confusing ones.
This is a table top model. Also a cathedral.
Thanks for the response
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Cliff Jones
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PostSubject: Re: dog bone resistors   2014-05-27, 8:14 pm

There are some resistors that are difficult to read. For example White body, White tip, and Red dot. That would read 9900 = 9.9K Ohms But if you read it as an orange it would be read as 990,000 ohms or 990Kohms. Now here is one issue with Philco, sometimes the colors were a little bit off color, so a red may be actually an orange and vs/vs.

They also had two different colors for Gray (Grey) one was battleship grey and another type which I forget at the moment.
So even shades of colors could be non-consistent. Now here another issue in the three page beitman of the model 19-128 they list a white, white, orange as a 100Kohm in the resistor data table 3. Riders volume 4 section 4-pages 18-19-20 part #45.
So evidently they didn't follow a set of colors such as RMA. Strange (well its close to 99Kohms and well within 20%) so go figure. Suspect 

The best way is to measure and see how close to the colors they are if you can't follow a schematic.

I have seen what you say as half one color and half another color but have found no explanation. If there were just one color then that color would be probably a cap rather than a resistor (that's just my opinion so don't rely on me)

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Cliff Jones
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PostSubject: Re: dog bone resistors   2014-05-27, 8:25 pm

This is from an old post on ARF:

Those resistors have an early color scheme unique to Philco. They came before the RMA standard color coding used on dogbone (body-end-dot) resistors. Their color scheme on the early resistors can be confusing because for several differenet colors, they used two different shades--and each shade indicates a unique value! So, for example, you have to determine if you are looking at "battleship grey" or "silver grey" as they are NOT the same value! Same is true for at least two other colors.

A listing of the colors and the associated resistor value is available in a book that specializes in Philco part information and values. It is still in production, copyrighted, and I've never seen the info made available online.


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confused1



Join date : 2014-05-25

PostSubject: Re: dog bone resistors   2014-05-28, 7:48 am

Thanks Cliff
I found a few web sites that give some sense to the philco way for color coding.
I am only going to replace the ones that are out of tolerence and are readable for now. I'm going to compare the color set up to see how close they come.
I've read some where that some caps do look like resistors...so you are correct about that. I'm going to tread lightly on those.
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