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Mar 23, 2020, 07:48 PM
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Evan D's Avatar
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Help with resistor color codes


Looking for some help. I have to replace a resistor in a charger. The color code doesnít make sense to me. Without trying to preconceive what someone may think here is a picture. Itís in the AC conversion to DC circuit.

Thanks in advance.
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Mar 23, 2020, 08:53 PM
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E-Challenged's Avatar
You can look up resistor color code info by Googling. Are you sure it's a resistor?
Mar 23, 2020, 09:20 PM
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Evan D's Avatar
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I did look it up plus I remember the song for the codes but it doesn’t make sense so I’m asking for help. Sure looks like a wire wound resistor to me.
Mar 23, 2020, 10:12 PM
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Wintr's Avatar
Code is 0 through 9: black-brown-red-orange-yellow-green-blue-violet-gray-white.
If the colors are what I see them as (brown-black-white), that is a very large resistance; 10 * 10^9, or 10^10 Ohms. Not exactly a common value. It may, however, be an inductor, or a capacitor, which would not only make the codes different, but more likely a real value
Mar 23, 2020, 10:50 PM
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rocketsled666's Avatar
How do you know this component needs to be replaced? Seems like something you couldn't possibly guess. If you've got the chops to figure it out for yourself, I don't think you'd be asking about color codes. So I'm guessing someone told you it needed to be replaced? If so, maybe that same person could tell you where to find a replacement? Given its size and lack of heat-related discoloration I'm going to go with "Inductor" vs. "Resistor". Large resistors are large so they can withstand a lot of heat. That part doesn't look like it's ever been particularly warm never mind hot. It's not a power resistor.
Mar 24, 2020, 03:24 AM
Registered User
Hi,
That's a fairly large part and I don't think it's an inductor or a capacitor. It certainly won't be 10^10 ohms - imagine the volts you would need to justify a resistor of that size of that resistance.
Could that third colour be silver? That would make it 0.1R which would make more sense. Is that scorched pad below the part a result of you trying to remove it or original heating from the part?

Cheers,
David
Mar 24, 2020, 03:34 AM
Flying R/C since 1964
kallend's Avatar
White for the multiplier makes no sense in that application or in the size of the component. I agree with David, it's silver and it's a 0.1 ohm power resistor.
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Mar 24, 2020, 07:22 AM
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Evan D's Avatar
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Thanks, that was my problem the multiplier band really looks white and that would make it 10G ohm. It’s in the AC to DC converter in a 600W power supply. The scorched board is from it burning out, not my removal. The pad and trace will be replaced by a wire.
Mar 24, 2020, 08:13 AM
Registered User
The problem today is there is NO standard layout of the color bands. The black band ON a white band is something I never saw in 66 years of USA work. What does a Ohm meter read with it out of the circuit ? Are you POSITIVE it is the bad part ?

It does not look over heated enough to me. It could be a inductor.
Mar 24, 2020, 08:17 AM
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Evan D's Avatar
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Reads open. I'm positive.
Mar 24, 2020, 08:21 AM
That's what I wanted it to do
MrEFlyer's Avatar
Quote:
Originally Posted by cyclops2
The problem today is there is NO standard layout of the color bands. The black band ON a white band is something I never saw in 66 years of USA work. What does a Ohm meter read with it out of the circuit ? Are you POSITIVE it is the bad part ?

It does not look over heated enough to me. It could be a inductor.
The black band indicates it is a bifilar wound wire resistor.
So to get to the answer it is a .1 ohm power resistor.

It's also doubtful that it is open or that anything else could be wrong with it.
Mar 24, 2020, 08:23 AM
Registered User

Not many choices for you ?


Remove it . First take a picture of those colort bands & the spacing of the bands. Then SLOWLY crush the coating in a vise. SLOWLY. You are trying to see if it is a wire wound power resistor. Or a large carbon resistor. Or a inductor. W ires can be measured with fine pointed tips. That is what I would do on the unit.. Get lucky.
Mar 24, 2020, 08:31 AM
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Evan D's Avatar
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Thanks, I'll look at it again. Seems it's most probably a 0.1ohm.
Mar 24, 2020, 09:33 AM
Registered User
My guess is that is a very low ohm - probably .1 as you say. And it is a higher wattage - replace it with a 2 or 3 W at least.
Mar 24, 2020, 09:42 AM
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rampman's Avatar
I am not doubting your finding it as OPEN but to me that burn on the PCB is from a poor connection of the resistor to the PCB.
Yes, soldered in...but with the power that guy has going through it...over time...
If it was mine I would remove the resistor, clean the leads and the PCB and solder it in again but be sure there is great penetration to the lead and PCB and check the fix. You may be able to clear some coating off the trace on the PCB and add solder to this area to increase the heat removal so this hopefully doesn't repeat itself.

Rick

Rick


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