Electronics > Beginners
Non-standard resistor value?
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overlordManny:
Hi everyone. I'm a bit of a noob. Even though I've been formally trained in electronics by the USAF it's been many, many years since I've done much electronics repair work.

I have an old Nintendo 64 power supply that's giving me no output at all. I'm not terribly familiar with switch mode power supplies, but from what I can understand it looks like I may have an open somewhere on the primary side( no fuses blown). I found a resistor that seems to be reading high at 68.2M ohms. When I look up the color code, (blue, grey, green, gold, green), it looks like it should be 68.5 ohms at .5% tolerance, which is apparently non-standard. Looking at the numerical values, they seem too close to be a coincidence. What am I missing/not understanding. Here's a picture...
tooki:
Could it be a fusible resistor that uses a nonstandard color code, at least for some of the bands? (I think there was a discussion of those on here a few months ago.)
golden_labels:
digit1 | digit2 | multiplier | tolerance | temperature coefficient?
That would be: 6.8MΩ, 5%, 20mmp/K.
overlordManny:

--- Quote from: golden_labels on February 14, 2019, 04:14:12 am ---digit1 | digit2 | multiplier | tolerance | temperature coefficient?
That would be: 6.8MΩ, 5%, 20mmp/K.
--- End quote ---
That correct! I just found this on allaboutcircuits, amazing how you find answers after you post questions.

"Color Code Exceptions
5 Band Resistor with a 4th Band of Gold or Silver

Five band resistors with a fourth band of silver or gold form an exception, and are utilized on specific or older resistors. The first two bands represent the significant digits, the third band is a multiplication factor, the fourth band is for tolerance and the fifth band is for the temperature coefficient (ppm/K)."

Guess that's not my power supply problem. haha The search continues.
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