Posted: 1/4/2026 4:10:07 PM EDT
[Last Edit: Andrewh][Edited]
 I think this is a 1 ohm resistor, but wanted to make sure. it goes to a 400 watt power supply to convert 18 volts to 110 ac. I was testing it out to see what kind of load I could get out of it and it stopped working. pulling it a part, it looks like this resistor ate itself. is there a spec I should look for to have it take more power or am I limited by something else? I see wattage at the end of the resistor listings for 1 ohm, but am not sure how to tell what this one is. https://www.ar15.com/forums/manageTopic.html?b=1&f=124# |
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Originally Posted By Andrewh: I don't know how to tell that either. the board was setup for part of a 400 watt conversion from 18v dc to 110 ac. it is a little bigger than what I have dealt with in the past on regular electronics, but isn't huge. is there some diameter guide? You won't be dumping 400w across that resistor. It'll become magic smoke in a flash if you do! It.is likely for a measurement or control circuit. Where I work we make 100w resistors and keeping those cool enough to not derate can be interesting. What is the length/diameter of the resistor?. |
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Originally Posted By Andrewh: best guess is about .75 inches long and about 1/8th in diameter. Interesting. For something about that size we go up to ~1w in free air for the basic axial resistors. A data sheet or schematic would be very helpful. Also, figure out what allowed enough current through to fry the old one.or it'll happen again. |
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I can trace a board, but no idea how to figure out what let too much power slip by. I also found a thermal sensor just hanging in the air. guessing that might not have helped. I was thinking just a cheap part, hadn't thought that another part up stream might allow this to happen. not much on line about this company or board. no tear downs or anything. |
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the company doesn't respond. directly, or through amazon. phone number doesn't work, webpage doesn't work. I tried using mouser and digikey for their color coding calculator. if it is black, brown, silver and brown, then it doesn't exist in either catalogue. if it is gold instead of silver, then it exists. everything I see says by size it is a 2 watt probably. it is .59 to .6 inches long .157 to .16 in diameter. my only concern is that even if I go back down to no watt choice, nothing either sells is the same color coding as what I have. they all color code it differently to get that 1 ohm I guess. is that a manufacturing standard or age? date code on the board says dec of 2023. I found a number that links to a UL cert but no diagrams or anything available. e311990 https://productiq.ulprospector.com/en/profile/203229/zpmv2.e311990?term=ZPMV2&page=34 |