1. Home
  2. Electronics Repair
  3. More Rice Cooker Failures

More Rice Cooker Failures

I've worked my way through four rice cookers, two different brands, in as many months. The failure mode is consistent - the cooker cooks the rice, and then fails when it goes into the mode where it keeps the rice warm.

In each case, it seems that the temperature sensitive fuse has blown.

I'm in Australia, where the nominal mains voltage is 240V, but I actually get more like 250V. I'm trying to figure out whether this can really explain these multiple failures. The warming mode involves having an extra component in series with the heating element. I speculate that it is a capacitor, though if it is, its value is less than my multimeter will measure.

Anyone have any thoughts on whether these things really run so close the edge in warming mode that a 4% overvoltage can kill them?

Sylvia.

Reply to
Sylvia Else
Loading thread data ...

Check the power label on the cooker to make sure that it is rated for your mains line voltage and mains frequency.

Contact the dealer who sold you the rice cookers and tell them about the problem you are having.

--
Personally, I would prefer to use a good old fashioned pot on the stove to 
cook my rice. It is usually much less of a problem this way...
Reply to
JANA

Sylvia Else wrote: : I've worked my way through four rice cookers, two different brands, in : as many months. The failure mode is consistent - the cooker cooks the : rice, and then fails when it goes into the mode where it keeps the rice : warm.

: In each case, it seems that the temperature sensitive fuse has blown.

: I'm in Australia, where the nominal mains voltage is 240V, but I : actually get more like 250V. I'm trying to figure out whether this can : really explain these multiple failures. The warming mode involves having : an extra component in series with the heating element. I speculate that : it is a capacitor, though if it is, its value is less than my multimeter : will measure.

: Anyone have any thoughts on whether these things really run so close the : edge in warming mode that a 4% overvoltage can kill them?

: Sylvia.

The keep warm rice cookers I've seen use a secondary warming coil separate from the main cooking coil. I would doubt the extra component is a capacitor, maybe thermal fuse. Is there continuity in the heating circuit? Its possible the overvoltage could have blown a thermal fuse, it all depends on how much margin was used when selecting the fuse.

Reply to
kmy

Now that I have yet another new one to play with, it appears this extra component is a resistor of some sort - apparently it also burned out when the rice cooker failed. Its resistance, when cold, is 1.2K.

This is what it looks like. The ruler is in centimetres, so this component is about 2.5 inches long.

formatting link

The restance of the main heating coil, when hot, would have to be about

140 Ohms (given that it's rated at 400W at 240V).

The main heating coil remains in circuit in warming mode, in series with the other component, but clearly, given its resistance, it will be dissipating little heat. I think it's done that way simply to avoid needing a double throw switch - it reduces the cost a bit. The other component is mounted on the heating plate, so it would be providing most of the heat for warming.

The failed component had some discolouration, but given that this new one has probably never been heated up, it's hard to know whether the discolouration means anything.

If the average punter knew how these things are put together....

Sylvia.

Reply to
Sylvia Else

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.