This is the resistor from my macbook power supply.
It *look* to me to be black, orange, white (or grey), silver, brown.
What is it?
Tim
What are the colours? it not sane to have the first band as black=0
it *ought* to be 39 ohms 5% 100ppm/°k But I would have expected that to be orange white black silver brownm.
Maybe I've read them in reverse? Anyhow, I *did* post a link to a picture...
Tim
I cant tell if the bands are white or silver and whether the end band is red or brown.
Cameras are not that hot on colour sometimes
Second one down from the top is definitely silver. Top band looks brown to me but I?m no expert at reading these.
Tim
Silver tolerance is 10%, not 5%. Other than that, agreed it's as you say.
I reckon silver is the multiplier x0.01 and it is actually 0.39 ohm. E12 value shifted along with a leading zero> Not seen one before. Red or brown is probably the tolerance.
Most of my small power resistors have the value in small type face.
039 * 0.01 = 390mR 0r 0.39R, and 1% for the brown. (I use R for ohms)
Cheers
Yes, my thoughts too. Don't see silver or gold multipliers too often.
Confirmed by this site.
+1
Black = 0 Orange = 3 White = 9 Silver x .01 Brown 1% tolerance
Yes, you are right - it's not 39 ohms. That's a useful webpage
I'd write that as 0R39, just as I'd write 4.7Kohm as 4K7
SteveW
You'd be wrong then. Should be 4k7, it's kilo not Kelvins.
Cheers
The silver isn't a tolerance. It's a multiplier.
In the first case yes - I mis-typed a capital K, while pre-occupied with why Windows has changed some of the Alt/Numeric combinations, but not others (ALT-248 still gives degrees, but ALT-234 apparently no longer gives the ohms symbol and ALT-0937 doesn't either)`. It seems odd to change something that has been around since DOS days, when most of it seems unchanged.
In the second case, many circuit diagrams and technical drawings traditionally use only upper case letters and would normally use 4K7 rather than 4k7, so either is acceptable there.
SteveW
Then there are those times when an AK47 is more than enough...
I cannot see the value, but maybe its a vdr that has dumped an over voltage and been destroyed. One reallly needs the circuit, otherwise all would be guesswork, but its going to be quite a low ohmage since to burn out anything bigger would need more volts, assuming its not on the mains supply side. Brian
It sounds jolly non standard to me. Brian
Yes but a resistor of that value is normally a more high wattage device. What would one have such a low value for in such a low wattage, since the ruddy power cable is a fair percentage of that. One would not use a fusable resistor these days. Brian
However, going back to the original thread on this, 1, how many wires are in the cable to the laptop? If its only two, have you actually ascertained there is no damage to this cable, ie a short? If yes, do we still not know if it is switch mode or not, I'd really be surprised if its analogue myself, which then makes me suspect that its terminally damaged, as many of these use a custom chip and maybe a couple of high voltage semiconductors and a ridiculously tiny transformer, followed by fairly conventional circuitry but they need quite a lot of filtering. Many do have a feedback network to maintain current or voltage, and some have a multicore cable to allow the charging circuit to mostly be in the psu, but not always. If the mac book is a good recent model, for goodness sake by a real apple replacement for the thing or you might brick the laptop. Brian
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