Help identifiying these resistors

Thread Starter

OVERPOPULATION

Joined May 6, 2018
1
For a set of Logitech speakers resistors R79 and R80. Both are identical and both are fried. I ask because im unsure about the colors. I went to a local electronic components shop and the guy was unsure also. I think light is better on the pictures. Ive read around some guys saying it is 5,6Ohm but ive also found some contradictory info so i need a neutral view as those colors look a bit unusual next to what im used to see in local components.


 

ebp

Joined Feb 8, 2018
2,332
Though it would be rather time consuming, you might try carefully scraping the outer coating from one of them and trying to find an intact "turn" that you can measure with a meter. The resistive material is probably metal oxide film, and it is reasonably likely that each resistor has gone open-circuit only in a fairly localized way. If you can measure a turn and count turns, you might be able to get a reasonably accurate estimate of the original total resistance.

From your first photo, I would estimate that there are around three turns. The resistive material is laid down as a cylinder on the surface of a ceramic rod and a spiral cut is made leaving ribbon-like "turns."

They may be "flameproof fusible" resistors - made specifically to reliably fail open-circuit and not catch fire due to gross overload. Typically such resistors are used in a semi-protective fashion like a fuse, so if they do fail it generally means something else has failed first.

Speaker model? - someone at AAC may own the same type and be willing to open the case for a peek inside (photo of speaker would save people from having to check model numbers unless ...)
 

danadak

Joined Mar 10, 2018
4,057
4.7K ? Yellow Violet Red

Maybe take pic and try to enhance its color saturation to force
better color appearance.

Regards, Dana.
 

Raymond Genovese

Joined Mar 5, 2016
1,658
Yes, a puzzle.
For easy reference (From http://www.physics-and-radio-electr...e-components/resistors/resistorcolorcode.html ):


It’s clearly a four band resistor.

The tolerance band and the multiplier band very much look like the same color. Brown, red or gold are the logical and most reasonable possibilities, in my opinion.

Now, if you had taken the pictures with proper white balance and with a color standard, it would made things much easier. That being said, here are my best guess entries.


red.jpg

2% Brown, Black, Red, Red = 1K, or Brown, Gray (not Silver as originally written), Red, Red - 1.8K


brown.jpg

1% Green, Black, Brown, Brown - 500 Ohm


gold.jpg

5% Green, Black, Gold, Gold - 500

There are other possibilities.
 
Last edited:

ebp

Joined Feb 8, 2018
2,332
I'm guessing the resistor is rated at at least half a watt, which means it would take something over 30 V to fry it if it is 1.8k. Possible in Logitech speaker ???

500 ohms is not a standard value and very unlikely, given that 510 ohms is a standard value and Logitech products are mass-market.
 
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