Resistor Colour Code?

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Resistor Colour Code?

This topic has 10 replies, 9 voices, and was last updated 30 July 2022 at 11:44 by Steve Neighbour.

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28 July 2022 at 19:23 #607685
Peter Cook 6
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@petercook6
I have a dead LED batten. Opening it up I found that a wire wound resistor had overheated – and gone open circuit. However I cant figure out what resistance it was supposed to be.

It's a 5W(?) series resistor between the incoming 240v mains and the control circuit.

The colour code seems to be Red-Black-Gold-Gold-Black which beats me. Two gold bands seems to have escaped my code charts. As has a black tolerance band. But Black as the first digit also seems wrong!

Can someone with more electronics experience possibly give me an idea of what It might be.

Thanks
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28 July 2022 at 19:23 #32272
Peter Cook 6
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@petercook6
28 July 2022 at 19:46 #607688
Les Jones 1
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@lesjones1
This will be a fusible resistor that forms the function of a fuse.There will be other failed components that have caused this resistor to fail. You will need to identify and replace ALL the components that have failed.
I think the resistor was probably 2 ohms. 20 x first gold multiplier of 0.1. second gold tolerance. I think the end black possibly indicates that it is a fusible resistor.

Les.
28 July 2022 at 19:47 #607689
Anonymous
A wirewound non-precision resistor is unlikely to use four bands to determine value. To me the leftmost band looks brown rather than red. So I take the resistor to be as follows, from the left:

Value: Brown Black Gold – 10×0.1 = 1 ohm

Tolerance: Gold – 5%

The rightmost black band could be temp coefficient, in which case it is 250ppm/K, ie, not very good.

Andrew
28 July 2022 at 19:47 #607690
noel shelley
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@noelshelley55608
20 Ohms ? 5% and 5watt ! Noel
28 July 2022 at 19:48 #607691
Anthony Knights
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@anthonyknights16741
Gold as a multiplier is x 0.1 ohms. Gold as tolerance is 5%. That would make your resistor 2 ohms if it wasn't for the 4th black band. Don't know what that is there for.**LINK**
28 July 2022 at 21:07 #607701
peak4
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@peak4
I believe the final black band indicates that it is non inductively wound.

Have a look at this data sheet
https://www.yageo.com/upload/media/product/productsearch/datasheet/lr/YAGEO%20NKN_datasheet_2021v0.pdf

Bill
28 July 2022 at 21:43 #607707
Peter Cook 6
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@petercook6
Thanks folks. Mystery solved, the fusible resistor suggestion led to Queen Mao Electronic – Products – Resistor Color Code

That site says "If an additional fifth band is black, the resistor is wire wound resistor. If an additional fifth band is white, the resistor is fusible resistor." I had not seen that before.

So it's probably a 1 (or possibly 2) ohm 5% wire wound 5 watt resistor. I can't see any signs of damage elsewhere on the board. I am thinking that the sort of power it would take to blow that resistor would have left some sort of evidence on the rest of the board which is mainly surface mounted IC's and resistors.

I might venture a repair. The unit has been replaced by the supplier under warranty, so it's an academic exercise

Thanks again.
30 July 2022 at 02:32 #607850
John Reese
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@johnreese12848
A mnemonic for remembering the order of colors: Bad Boys Rape Our Young Girls But Violet Gives Willingly.
30 July 2022 at 09:01 #607867
Nicholas Farr
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@nicholasfarr14254
Hi, another way to remember the order of colours and without incriminating anyone by fact or hypothetically is;

0 blackberries, 1 brown bear, 2 red roses, 3 oranges, 4 yellow yachts, 5 green grasses, 6 blue-bells, 7 violet violins, 8 grey graylings and 9 white whales.

Regards Nick.

Edited By Nicholas Farr on 30/07/2022 09:03:49
30 July 2022 at 11:44 #607880
Steve Neighbour
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@steveneighbour43428
Posted by John Reese on 30/07/2022 02:32:24:

A mnemonic for remembering the order of colors: Bad Boys Rape Our Young Girls But Violet Gives Willingly.

Which equated to Black, Brown, Red, Orange, Yellow, Grey, Blue, Violet, Green, White (I think)

I was taught a different one to that back in the politically incorrect 70's

Probably can't repeat that nowadays

(first word was 'Black' and V = 'virgin'

I'm sure those old enough will remember the rest !!
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