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Sous-vide heater
Got into a bit of a pickle with a Ary SV-1 immersion heater. Seems the pump got a piece in it and stopped working. These things run 14 hours or more UN-attended, so motor heat was probably high. I opened the pump up, removed the blockage and nothing. It’s a 12 volt DC 4 watt brush-less motor. So I contact Ary and they have no pumps. They don’t have any service for them either. Only the Vacmaster’s. So now I either buy a new one or fix this one. Ohm out the motor and it has a whopping 3K of winding resistance. Sounds a bit to high for any motor I ever worked on. The board is putting out 11.5 volts.
Has anyone ever measured a small 4 watt motor winding and what should it be?
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10 Replies
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Most electrical calculations involving resistance, voltage, current or power are solved using Ohm’s law. Ohm’s law, discovered in 1827 by Georg Simon Ohm, states that the current in a conductor is proportional to the voltage and inversely proportional to the resistance. Since power, measured in watts, is a function of voltage and current, and current is a function of voltage and resistance, it is possible to calculate resistance from power and voltage. The calculations are simple but an understanding of simple math is advantageous.
Enter the power, in watts, into the calculator. Divide the wattage by the voltage. The result is the current because Ohm’s law states that current = power / voltage. Record the current value for later use. For example if the power is 100 watts and the voltage is 50 volts, the current is 100 / 50, or 2 amps.
Calculate the resistance, in Ohms, by dividing the voltage by the current. Ohms law states that voltage = current x resistance, so by rearranging the formula resistance = voltage / current. Using the example in Step 1, with a voltage of 50 volts and a current of 2 amps, the resistance is 50 / 2, or 25 ohms.
Per sciencing.com
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Damn, if I just posted that not quoting the source I would have sounded smart. haha
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That WAS a well put explanation of the relationship between voltage, resistance and current. But Ohm’s Law calculations using results from an ohmmeter can only be done on purely resistive loads…such as a light bulb, a heating element, a resistor…and such.
Any type of a load in an AC circuit which employes a coil or coils of wire to create a magnetic field (speakers, motor windings, relay or contactor coils, etc.) produce another kind of resistance called INDUCTIVE REACTANCE. Inductive reactance is the opposition to current flow caused by counter-EMF (backwards voltage) induced into the winding due to relative motion. It’s called “relative” motion because it can either be physical motion (such as a rotating motor armature/rotor)…OR the mere act of the expanding and collapsing magnetic field resulting from changes in source voltage (the way a transformer works in an AC circuit).
So, ALTHOUGH we ALL should have an intimate understanding of Ohm’s Law in order to understand electricity and to effectively troubleshoot it, we must ALSO realize that Ohm’s Law can’t be used to calculate things such as amperage and wattage for a circuit with an inductive load. In OUR case, those would be motors, compressors, relay/solenoid coils.
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No clue what it ought to be.
I think you are well versed in ohms law but not a bad suggestion.
Did you try reaching out to the manufacturers tech support? Normally, they know and will provide the info.
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That definitely doesn’t sound right – and if my math is right, you are measuring 0.04W on it, which I doubt would be able to get any motor turning. Unless your meter is off, you should be seeing around 33Ω. Sounds like a busted motor to me 🙁
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That’s what I got too. Thought my math was off. As for meter, I actually dug out my probe bag to double check for errors. It’s the first tine that phone type piercing clamps got no reading. Wire must be very fine for that to happen.. So I had to get out the Fluke needle probes to go in the back of the plug. Used a Kelly clamp to hold the plug vertical. Such a small plug and such big fingers makes it difficult.
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Whatcha cookin’ for 14 hours? I did a prime rib that way for Christmas, but most things get no more than a 4 hour bath. Mine is a domestic use Anova.
One of our restaurants had a rather sizable commercial sous-vide unit they wanted us to fix. Probably a vacmaster product too. The manufacturer said they don’t sell parts to repair, but they DID replace it once we gave them a serial number and found it was still under warranty.
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Pork Butt
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Conversed with Ary on it. No parts. But I’m well out of warranty. I’ve had to buy several parts for my chamber vac. Including a lid. They crack from all the pressure and flexing.. This machine was almost $500 at the time I bought it. There wasn’t much out there back then. Annova came out with there first one the same month I bought the SV1 at $99 special.
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