| Electronics > Beginners |
| What are those? |
| (1/4) > >> |
| epigramx:
I know the second (at least) is probably burned, but it's weird both have an "1WJ" identification mark. PS. They are both from an HP Laptop PSU. |
| kars:
i think they are power resistors probably used as a current shunt to measure the current input/output in the psu |
| epigramx:
--- Quote from: kars on September 27, 2019, 06:10:40 am ---i think they are power resistors probably used as a current shunt to measure the current input/output in the psu --- End quote --- I noticed the PCB has R051 and R051-1 for them which made me think they are resistors (but they didn't look like resistors I know of). To replace those is there a safe alternative or do I need the exact ones? (e.g. regular resistors) PS. I'm not sure what the original models of those are to begin with. |
| TomS_:
--- Quote from: epigramx on September 27, 2019, 06:13:48 am ---Resistors to measure current? I don't get that. --- End quote --- You can measure the voltage across a resistor of a known value to determine the current flowing through it. |
| Warhawk:
--- Quote from: epigramx on September 27, 2019, 06:13:48 am --- --- Quote from: kars on September 27, 2019, 06:10:40 am ---i think they are power resistors probably used as a current shunt to measure the current input/output in the psu --- End quote --- I noticed the PCB has R051 and R051-1 for them which made me think they are resistors (but they didn't look like resistors I know of). To replace those is there a safe alternative or do I need the exact ones? (e.g. regular resistors, and I'm not sure what the original models of those are to begin with) --- End quote --- These are typically low-value resistors. Current through the resistor creates a voltage drop across it as per Ohm's law. A followup circuitry then treats the voltage drop as a current information. https://www.powerelectronictips.com/measuring-current-shunt-resistors/ The magic google formula would be "shunt based current measurements". Such resistors are also known as "shunts". If I read this correctly, the A sample is 0.22 ohm (220mOhm) and the B sample is 0.13ohm (130mOhm). You shall replace them with the same power rating (they can get hot). |
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