Strange color code on resistor, Help!

[double]

Hello all,

I am looking to replace a torched resistor, I am repairing a Power supply and replaced the affected transistors already but still have not figured this resistor out. The color code seams to be BROWN, BLACK, SILVER, GOLD, SILVER,.. which does not make sense, even if the 5th was a "reliability" band.. It measures about 6mm so I believe its ¼ Watt. Its marking on the PCB is R301; definitely not a inductor. Any help would be greatly appreciated.

[budm]

Re: Strange color code on resistor, Help!

Is the 3rd really silver or Grey?

https://cdn.badcaps-static.com/pdfs/...2bf2eda94b.pdf

[double]

Re: Strange color code on resistor, Help!

Is the 3rd really silver or Grey?

https://cdn.badcaps-static.com/pdfs/...2bf2eda94b.pdf

Take a look at the high res photos. you be the judge..

The grays im used to tend to have a more flat matte look, in my experience. the brown and black have that matte look as well. the Gold/Silvers usually have more of a foil look. this is the first resistor to really puzzle me.


is it possible colors were altered when it burned out?

If the third was gray, the fifth would have to be too (they look identical) and that makes no sense as well because that would make the tolerance gray.

Whatever color it is, the third and fifth are the same, unless the color got altered, i don't think a manufacturer would make the gray and silver so close in appearance.

[stj]

Re: Strange color code on resistor, Help!

i'v seen these before.
i think - maybe, that the last band indicates the wattage.
because it's a fuseable safety resistor.

[redwire]

Re: Strange color code on resistor, Help!

It looks like a 0.1R 5% 1/4W metal film flameproof (pink body) resistor (BRN,BLK,SILVER,GOLD) and the 5th band can denote what kind of resistor it is. A white band usually means fusible (for Panasonic and Yageo). But yours is silver? I guess it's another brand. resistor calculator
Probably current-sense on the source/emitter of the SMPS power transistor.

[double]

Re: Strange color code on resistor, Help!

I was going to say, Iv heard of white bands denoting fusible, but not silver, but that makes the most sense. I just dont want to replace it with the wrong value..

[Andrew F. Ali]

Re: Strange color code on resistor, Help!

I'll start with a 10 Ohm. Then try a 1 Ohm, then the 0.1 Ohm resistors. Hardly think it would be 10 x 8-0s = 1 exp 9-0s may be stretching a bit. :-)

[budm]

Re: Strange color code on resistor, Help!

Can you show us the board and where the resistor is connected to?

[redwire]

Re: Strange color code on resistor, Help!

double, yeah a picture of the board helps.
That (sense) resistor going open-circuit would damage the IC too, from what I have seen.

[double]

Re: Strange color code on resistor, Help!

Sorry for the delay, here is a photo. hard to see because heat-sink is in place, you could see "R304" is where the resistor was pulled form.









I was looking for a 10.8 ohm resistor with a .05% Tolerance. No dice at mouser or digikey..Actually digikey has a 10.8, .5% 1/2 Watt, which maybe my safest available bet to start..

Let me know what you think.

[bammbammfran]

Re: Strange color code on resistor, Help!

your last band is silver so it should be 10%
digikey does have a 10.8 5% but NOT IN STOCK
you're best bet is probably an 11 ohm 5% which they have in several wattages
yours is probably 1w based on size, I would go for 2

[double]

Re: Strange color code on resistor, Help!

your last band is silver so it should be 10%
digikey does have a 10.8 5% but NOT IN STOCK
you're best bet is probably an 11 ohm 5% which they have in several wattages
yours is probably 1w based on size, I would go for 2

If the last band is silver than so is the third, they are undoubtedly the same colors. It measures about 6mm so I believe its ¼ Wattr..I contacted digikey technical support and they are baffled as well..Id buy another power supply if they weren't so much compared to the cost of the resistor : /

[bammbammfran]

Re: Strange color code on resistor, Help!

well since the 4th is gold, I do not think that the 3rd band is that critical
the 1watts are 6.5 mm in the 11ohm

they do have the 10.5 in 1/4watt MFR-25FBF52-10R5
and 10.7 in 1/4watt MFR-25FBF52-10R7

for .2 ohms difference, ASSUMING yours is a 10.8, I would use the 11 and a higher wattage

they are cheap enough at about 10cents ea, get a couple of each ??

[bammbammfran]

Re: Strange color code on resistor, Help!

well
I did a bunch of searching and reading datasheets and I found 4 resistors that had a 5th band that was not for tolerance
but non were silver
I found a white (flameproof), black (flameproof noninductive) and violet (high power) on Yageos
and a blue (flameproof) on a TT electronics
A few companies do not even mention color codes on their datasheets which didn't help

I guess go with your note
"I'll start with a 10 Ohm. Then try a 1 Ohm, then the 0.1 Ohm resistors"

[budm]

Re: Strange color code on resistor, Help!

Can you tell me if one end of the resistor is connected to the + leg of the main filter cap? If it is, then it is fusible resistor for feeding the B+ to the circuit. And because it is blown open, then you may have shorted circuit some where so the components such as diodes, MOSFETs should be checked before installing the new resistor.

[bammbammfran]

Re: Strange color code on resistor, Help!

looks like we can add green to a fifth unknown band
I have several of these pink bodied ones with X-X-silver Gold-green

and I found an even more odd one
green bodied- red-red-silver-black-GOLD from an apple G4 supply

My tester isn't good under .5 and all these read under .4

So I guess that yours might just be a .1 - 5% with an unknown silver band

[budm]

Re: Strange color code on resistor, Help!

BTW, this power supply board, what is it used in? Any P/N? I can see it is made by DELTA.

[stj]

Re: Strange color code on resistor, Help!

green final band = 0.5%

maybe when we see stuff like this, we should meter them to get a bit of info built-up.
i'll keep an eye out from now on and make checks on strange parts.

[bammbammfran]

Re: Strange color code on resistor, Help!

green final band = 0.5%

maybe when we see stuff like this, we should meter them to get a bit of info built-up.
i'll keep an eye out from now on and make checks on strange parts.

that would be true with the green if the silver and gold were not 3rd and 4th
and I did meter them to below .4ohms which I did mention

[ben7]

Re: Strange color code on resistor, Help!

The last one might be the temp coefficient. Some manufacturers mark that on there as an extra band.