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Higher wattage for POT on variable power supply

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wolf9545

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I will start by linking back to an older post that I started for a problem I had with a meter display getting that to work. The first post explains the whole thing that I was trying to do.

https://www.electro-tech-online.com/threads/pm-1029b-meter-to-variable-computer-power-supply.113999/

Everything is working in the circuit for a while. The 2.5K pot that I have in there has been working fine, able to control the voltage for the variable circuit. When I do use the power supply I do not keep the unit plugged in for a long time (average time is around 10 minutes) while I am using it but somehow my pot died on me. If I take my multimeter and connect it to one of the outside contacts and the other prob to the middle I get either 0 ohms or ~2.5K ohms on my meter, even if I move the knob. Any idea on why the pot would just go? I didn't move any wires around to cause a short and was just using the meter yesterday. Do I need to upgrade to a higher wattage pot; currently I have a 1/2W pot in there.
 
Sounds like the wiper doesn't move even though the shaft does. Maybe over torqued it once?
 
To me it looks more that the carbon trace between the outer terminals is burnt up due to excessive current.

If you turn the pot wiper away from one outmost position and measure full resistance between the wiper terminal and one outer terminal - with infinite resistance before the carbon trace is burnt.

Boncuk
 
Under normal conditions the pot should never have to dissipate more than 1/4 watt (that's assuming a 120R fixed resistor, with about 10mA current through the entire divider.) So if everything is operating normally, your 1/2 watt pot should be fine.

Perhaps sometime in its history however, it endured an overdose of current before you got the circuit working correctly. Now the carbon is finally disintegrating. Does it smell burned? That's a dead giveaway that the pot has been stressed.
 
Nothing smelled / looked burned. I am wondering if the amperage was too much for the pot. If I stick my multimeter on the outputs, when the circuit was working and a long time ago, and placed it on AMPS I could register a total of 1.0A on the outputs. This is with just my multimeter connected to it. Is there a way to re-make the connections inside if I open the pot? I really don't think that any of the carbon inside is gone because if I connect my multimeter, set to ohms, on a center terminal and one of the outside terminals I get 0.0 ohms (my meter displays OL if there is no connection). If I stick the multimeter on the center terminal and the other outside terminal I get 2.5K ohms. To me, I might be wrong, that seems like everything is connected fine inside I just don't get any variable.
 
Stuff breaks, wears out, or just doesn't work any more for whatever reasons it felt like it.

You are over annalizing a common thing that just happens sometimes so just spend a $1 and buy and new pot.
 
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If I stick my multimeter on the outputs, when the circuit was working and a long time ago, and placed it on AMPS I could register a total of 1.0A on the outputs. This is with just my multimeter connected to it.

Please don't do that. When you plug the leads of a multimeter into the amp or milliamp jacks, this places what is effectively a dead short across the leads. If you connect the meter directly across an energy source this way, you will be measuring short circuit current, which could easily blow the fuse in the meter (if it even has one), or worse, cause it to catch fire, melt, explode, etc. For measuring current, the meter should be connected in series with a load.
 
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