Hello again

Here's a picture of a resistor. It has 5 rings.

First is brown, second black, third silver, fourth red and fifth black.

Problem is that I can't find any decoding info that shows silver as an option for the third digit.

There is grey. But that is definitely not grey in the picture. It's silver.

Here's an example of the decoding rules I am looking at:

https://www.arrow.com/en/research-and-events/articles/resistor-color-code
Anybody have any suggestions? Were the rules different when this resistor was fitted perhaps?

How do you handle this if you are trying to decode it?

Cheers

 

Hello,

Have a look at this page to decode the colors:
https://www.diyaudioandvideo.com/Electronics/ResistorColorCodes/
Bertus

 

It's wirewound, so it is a low value (looks like 10.2 ohms).

 

Hello,

Have a look at this page to decode the colors:
https://www.diyaudioandvideo.com/Electronics/ResistorColorCodes/
Bertus

That's a bit different.

So, in the case of this resistor, we have 109 x 100 = 10.9 KOhms.

How does that sound?

 

Hello,

The third ring looks silver to me and not gray.
Red,black, silver is a 10 / 100 = 0.1 Ohms resistor.
The fourth band , red indicates the tolerance of 2 %.

Here is also a page with standard resistor values:
http://educypedia.karadimov.info/electronics/resistancevalues.htm
Bertus

 

Ok. I'm confused. Can you please explain how you got to that figure.

This is a 5 band resistor.

It says "On a 5 and 6 band, the first three bands are the significant digits".

That being the case brown, black and silver gives us "109" accordig to the color chart.

It then say "The next band represents the multiplier or 'decade'. It says nothing about dividing.

In my case that's RED which gives us "x100" according to the color chart.

I am assuming the output of the calculation is in Ohms.

Which is how I arrived at 109 x 100 = 10.9 KOhms.

What did I miss here?

Thanks

 

Hello,

Just measure the resistor.
I expect it to be 0.1 Ohms.

Bertus

 

I also vote for 0.1 Ω, it's the only thing that immediately makes sense for the silver ring.

But I also wanted to take a look at what the function of the resistor is, does such a resistor's value make sense in the circuit?

 

As you can see in the picture it's attached to aboard. I don't want to mess with it.

 

I also vote for 0.1 Ω, it's the only thing that immediately makes sense for the silver ring.

But I also wanted to take a look at what the function of the resistor is, does such a resistor's value make sense in the circuit?

Ok. I understand. But can you please explain to me why the calculation I have posted above, which is based on the information given in the webpage, doesn't apply in the case of this resistor. That's what I am trying to understand here. I doubt, moving forward, that this will be the only time I will refer to that webpage so I would like to understand why the rules don't apply in this case. Appreciate it.

 

Could it be military spec?

Many sources refer to a military specification that can add a 5th band for reliability or temp coefficient. Black is a valid color for temp coefficient.. If it is a little wider than the others (e.g., 1.5 times as wide) , that would nail it down.

 

It's wirewound, so it is a low value (looks like 10.2 ohms).

Right. But then could you explain to me how you would use the color coding of its bands in this instance to calculate your 10.2 ohms value. It's the calculation I am interested in. If you don't mind. Appreciate it.

 

Could it be military spec?

Many sources refer to a military specification that can add a 5th band for reliability or temp coefficient. Black is a valid color for temp coefficient.. If it is a little wider than the others (e.g., 1.5 times as wide) , that would nail it down.

It's a TV power board.

 

Hello,

The third ring looks silver to me and not gray.
Red,black, silver is a 10 / 100 = 0.1 Ohms resistor.
The fourth band , red indicates the tolerance of 2 %.

Here is also a page with standard resistor values:
http://educypedia.karadimov.info/electronics/resistancevalues.htm
Bertus

Ahah! I just been back to the webpage. I can see where you got that 0.1 from. You have applied the 4 band rule. I didn't even look at that because it's a 5 band resistor. Ok. Confusion over.

 

I'm back and I'm all the way back to confused.

Been back to the chart on the webpage and had another look.

The 5 band rule doesn't have a silver option for the third band in that chart either. I took white (9) to be the silver option for the third digit. It's not.

The only set of rules that has a silver third band is the 4 band set of rules and that does work out at 0.1 ohm.

But this resistor clearly has 5 bands on it.

 

The only set of rules that has a silver third band is the 4 band set of rules and that does work out at 0.1 ohm.

But this resistor clearly has 5 bands on it.

So, accept THAT fact and rest in peace that the 5th band is something else like I mentioned above. The fact it is called a military standard doesn't others can't have followed it. For example, that resistor may be used in a circuit for which the temperature coefficient might be important. So, a resistor with such a marking was used.

Measure its resistance to confirm everything, and then move on.

 

So, accept THAT fact and rest in peace that the 5th band is something else like I mentioned above. The fact it is called a military standard doesn't others can't have followed it. For example, that resistor may be used in a circuit for which the temperature coefficient might be important. So, a resistor with such a marking was used.

Measure its resistance to confirm everything, and then move on.

No. Not going to do that. I need to know. Dog with a bone. I may be returning this board from whence it came so I'm not going to take an iron to it. They will know it has been tampered with. Taking a meter to it in situ is no good. Besides, it appears to be an anomoly. There must be an explanation someplace. I'll just keep looking.

 

Ok, I think I might be able to help here. I found a chart that explains the silver band in the 3rd position. As others have mentioned before, this 5 band resistor may be using the 5th band as a temp coefficient or fail rate indicator so you need to calculate the value as a 4 band resistor. Band 1 & 2 are the digits. Band 3 is the multiplier and band 4 is the tolerance. Brown = 1. Black = 0. Silver = x.01. So 10 x .01 = .1. Red = 2% tolerance. No idea what the final black band is for but hope this helps. Check the note at the bottom of the attached picture where it states that the 3rd digit is only for 5 band resistors. Your's appears to be a 5 band but is really a 4 band with a 5th "mystery" band as there is no temp rating or fail rate listed for black. Hope this helps with understanding. It is an odd one, that's for sure.

PS, I just checked the link you provided for resistor color codes. You can use your chart for this resistor but the resistor shown on your chart is a 6 band with 3 digits. Yours is a 5 band with 2 digits, then multiplier, then tolerance then temp coefficient. According to your chart, your resistor (final black band) has a 250ppm/K temperature coefficient.

 

Ok, I think I might be able to help here. I found a chart that explains the silver band in the 3rd position. As others have mentioned before, this 5 band resistor may be using the 5th band as a temp coefficient or fail rate indicator so you need to calculate the value as a 4 band resistor. Band 1 & 2 are the digits. Band 3 is the multiplier and band 4 is the tolerance. Brown = 1. Black = 0. Silver = x.01. So 10 x .01 = .1. Red = 2% tolerance. No idea what the final black band is for but hope this helps. Check the note at the bottom of the attached picture where it states that the 3rd digit is only for 5 band resistors. Your's appears to be a 5 band but is really a 4 band with a 5th "mystery" band as there is no temp rating or fail rate listed for black. Hope this helps with understanding. It is an odd one, that's for sure.


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Well it certainly makes sense if you ignore the 5th band as you say and treat it as a 4 band. The other thing is that 0.1 ohm seems unfeasibly small for such a large resistor. I know resistors are a great deal smaller these days but still. I have a 1M resistor that woud fit into that one about 20 times. I put a meter across it and it reads 0.8 ohms. But that's with it still on the board so it's not at all reliable because it's not in series. The other thing I notice is that the 5th band on that resistor is right at the edge of the resistor rather than a little further in like the brown one. That's not normal. Maybe it's not a band at all and just looks like one. Thanks for your response.

 

As a side note, if the last band is wide it is a mil-spec device. Some of the mil-spec precision resistors I have are wire wound and spec printed on the device and not color-coded. They are precise to within 0.1Ω. FWIW

EDIT: Ooops, it's the first band wide, dyslexia strikes again.