Resistor colour code help required

[Bryan Cedar 1Participant @bryancedar1]

<li style=”text-align: center;”>I have found an open circuit resistor in an expensive marine panel meter but am having difficulty in identifying its resistance value. two of the 5 bands are actually gold but I think gold has been substituted for brown but may be wrong. These are from an american circuit board. attached is a photograph of the faulty resistance
1. Scroll down for images.

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[Peter Cook 6Participant @petercook6]

There is a calculator here that gives a third band Gold as ÷10 so Grey, Red, Gold, Gold is calculated as 8.2 ohms plus or minus 5 %.

Hope this helps.

[Julie AnnParticipant @julieann]

Probably 8R2, ±5% and the white band is not part of the colour code. Looks like the resistor is part of some sort of power input filtering so a low value is plausible.

Julie

[Grizzly bearParticipant @grizzlybear]

Hello,

Confirmed 8.2 ohms.

Bear……….

[Keith PetleyParticipant @keithpetley53472]

Hi,

A fifth white band can indicate that this is a fusible resistor – it acts as a normal resistor but goes (permanently) open circuit if the current through it is excessive. Can be used as an in-rush current limiter and fuse combined. If this is the case here and it has gone open circuit you may need to find what caused it to fail in addition to replacing it.

Keith

[Chris CrewParticipant @chriscrew66644]

In less politically correct times I was taught a mnemonic by a college instructor for the resistor colour code that I daren’t repeat here now. I read somewhere a while back that someone had lost their teaching job because they had informed their students of this mnemonic but it has stuck with me for the last 57 years!

[GeorgineerParticipant @georgineer]

I’m glad you didn’t.  It was seriously unpleasant when I first heard it in the 1960s and I wouldn’t have dreamed of repeating it to any of my pupils, any more than some of the other sayings and jokes which folks thought were funny.

George

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I’ve not heard that one, but I was told how to remember the formulas for ohms law, by one of my collage lecturers, which probably isn’t a polite way of putting it now, or even back then.

Regards Nick.

[vintagengineerParticipant @vintagengineer]

Some manufacturers deliberately mis colour their components to stop copying.

[Adrian R2Participant @adrianr2]

It could also be an inductor, they can have 5 bands starting with silver, although probably not two golds.

Do you have a circuit diagram or any lettering on the board?

[Adrian R2]

On Adrian R2 Said:

It could also be an inductor, they can have 5 bands starting with silver, although probably not two golds.

Do you have a circuit diagram or any lettering on the board?

I agree, a 5 ring colour code is often found on inductors. But then the aggro starts!

Unfortunately manufacturers don’t seem too worried about using private variants of the inductor code.  They might colour code for stock control purposes, not to help repair men!  The item may never have been considered repairable, so no Service Manual either.  As electronics have become progressively cheaper to replace than repair, stuff is made with little or no consideration for anyone wanting to maintain it.

As Bryan’s colour rings don’t seem to follow any standard code (RC or L) the only way to be sure is to lift one end and measure it with an LCR meter.   Unlikely, but maybe it’s a capacitor, in which case it should be open circuit.

A circuit diagram would help:  judging by the picture, this could be part of an LC filter on the power input.  Could also be an RC filter, where a resistor drops the supply voltage to suit delicate components behind.  How many volts across the open circuit component?  AC or DC etc?   More clues required if the colour code is unreliable.

If guesswork is the only way, then Julie/Bear’s reasonable suggestion this is an 8.2Ω resistor is less likely to result in magic smoke than substituting an inductor.

Dave

 

 

 

[John HaineParticipant @johnhaine32865]

It would help to know what the ass0ciated meter is measuring!  If DC current this could well be a shunt resistor.  Some circuit tracing needed.

[John Haine]

On John Haine Said:

…Some circuit tracing needed.

+1

The circuit looks to contain a MOV and X rated capacitor, so power supply input protection. Should be simple enough to trace that part of the circuit.

The item could be an inductor, but isn’t a differential or common mode filter normally found in these circuits.

Julie

[Clive Brown 1Participant @clivebrown1]

To judge by the poor appearance of the LH soldered joint, the resistor might already have had some attention after original assembly.

[Bryan Cedar 1Participant @bryancedar1]

This was a very temporary resolder as “Item” was in and out of board

[Bryan Cedar 1Participant @bryancedar1]

Many thanks to all who responded. Many paths to follow. This digital panel meter is listed in the States at over $400 !!

hence my desire to get it working again. Item is made by Blue seas Marine. for the boating/marine industry.

[Bryan Cedar 1Participant @bryancedar1]

General reply to all those kind forum members who responded

The panel meter is designed for measuring AC volts current and frequency. The  “Resistor

is directly connected to one leg of the AC input. Printed near the “Resistor” RF1 which does suggest

it is indeed part of a filter.  I do not know what the almost one inch green cube contains.

Back to you all.

[Bryan Cedar 1]

On Bryan Cedar 1 Said:

…I do not know what the almost one inch green cube contains.

The green cube has X2 printed on it, so as described above it is a X-rated suppression capacitor intended for line to line use, ie, across live and neutral.

Julie

[Bryan Cedar 1]

On Bryan Cedar 1 Said:

Printed near the “Resistor” RF1 which does suggest

it is indeed part of a filter.

Or, I’d interpret it as Resistor fusible 1 ??

 

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