Need help to identify failed component in rice cooker

My rice cooker just failed.

It's given me many years of service, but now a component seems to have suffered some kind of mechanical faliure. It's a rather standard model with the typical Warm/Cook modes. The model, specifically is a Tanin TR-2002A. (You won't find anything Googling for it, except maybe, in a few days this Usenet post. :-)) Relevant data: AC 220 V, ~ 50 Hz 620 W.

The component was connected in series with one of the AC power inputs, and measuring over the poles gives me 0 Ohm of resistance.

Could somebody please help me to identify the type of this component? I suspect it may be a thermal fuse, but I'm not at all sure about the values required. Then again, it might be something completely different, and I'm not really sure about it.

A close-up image of the component can be found at

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(59.2 kB). The actual size of the component is approximately 15 millimeters from end to end.

Reply to
Per von Zweigbergk
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Looks like it could be a fusible link.

Reply to
Meat Plow

This looks like it is a crimp connection from the heating element to the screw terminals of the 120/220 VAC input. Failures of this type are common in resistive heating elements. The high current that passes through the point of failure causes local heating (due to bends, local impurities,etc.) which eventually, over many uses, causes a break.

Repairs for this are almost non-existent. Depending on what the other side of the connections looks like (e.g. the rest of the heating element) you may be able to use a crimp-style ring tongue terminal and crimp it onto the end of the existing heating element. This assumes there is enough room to move the element so that the ring terminal can attach to the mounting screw. I've seen hardware stores that carry ring tongue terminals that can accommodate #6 AWG. Note: if your heating element is a rod with a thick coating on it, and the coating is flaking off, the element is bad and beyond repair. Also, if you try to bend the rod to make it attach to the screw connection, you will most likely cause cracks in the coating, and the element will be useless.

The short story is that you probably should start looking for another cooker. I doubt that you will find any direct replacement for the element, which is what really should be done. Good luck J

Reply to
John Hudak

You need to get the terminology right.

"0 ohms" is a short. SOmething in that location with two terminals and shorted is unlikely to affect operation. If it's really zero ohms, then it will pass the current and everything will be fine.

If you actually mean "there's no ohms across it" then you really mean it has near infinite resistance, ie an open circuit. If that's the case, it's no wonder the rest of the thing doesn't work, it can't get power since this open device is preventing any power to get to the rest of the device.

On the other hand, even if it is open, chances are good it's not a particularly special device, though it is there to protect the rest of the circuit, either a fuse or something to limit current when things get turned on initially. It won't work without something there, but what it does is preventative.

If it really is open circuit, then you have to consider that it may not be the fault, but a symptom. If it's opened up, it might just have "worn out" but it may have "blown" because something else in the unit is bad, causing this component to go with it. Until you determine whether there is something else at fault, replacing this component may merely mean it "blows" again.

On the other hand, it may be that simple, replacing it does fix the problem.

Michael

Reply to
Michael Black

Nope. That's not it.

There's a wire from the terminals of the 220 VAC input, going to a screw terminal, passing through this component, and then going into the rest of the appliance via a wire from another screw terminal. The connection to the heating element is intact, however, the actual component in the picture seems to be broken.

Reply to
Per von Zweigbergk

Yup. The component presents 0 ohms, a short, whatever. It'd pass current if the ring terminal were still intact. However, the actual component is physically damaged, which is why I want to replace it.

I probably could make the cooker functional (though probably not very safe) by shorting over where that component used to be with moderately thick wire. I haven't tried this yet though, and I don't want to try it before I've identified the failed component.

Reply to
Per von Zweigbergk

In that case, what would "170" mean? 6A probably means the component is rated to pass 6 amps of current.

Reply to
Per von Zweigbergk

It looks like a current or thermal fuse. Could the 170 mean it opens at 170C ? It is very common for appliances with heating elements in them to have a thermal link/fuse.

Jim

Reply to
James Beck

Temperature that it fails at in centigrade? That's a wild guess which is all I have :)

Reply to
Meat Plow

I thought it might be additionally helpful to take a picture of the innards of the rice cooker, to illustrate where in the circuit the mystery component was located.

It can be found at

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Reply to
Per von Zweigbergk

To me it looks like a terminal lug from the end of a thermal fuse or thermostat.

What is the maximum rated temperature of the cooker? Knowing that, I would install a cartridge-style thermal fuse or thermostat into that ceramic block in series with the AC mains in the photograph with a value about 20 degrees F higher than the max. rating of the cooker. Inspect the method of thermal contact inside that block; it may be useful to use refractory cement to make good contact between the business end of that thermal block and the new thermal protection device.

You could even salvage a thermostat from a drip-style coffee maker which may be about the right temperature (these units are easily found in the trash, rummage sales, etc. in the States).

Regards,

Michael

Reply to
msg

It's probably not the thermostat, since it had no direct contact with the cooking area whatsoever, it was just suspended in the air between those two terminals just right of the line input.

As i said, the component was really small, though the image makes it look monstrous. Something like 2 centimeters from top to bottom (in the image).

As for the thermostat, I think, though I'm not sure, that is the block covered by the metal plate at the right of the image. It has two wires going from it.

From what I've understood of the principle of operations of rice cookers, they have two modes. Warm, and cook. Warm activates low power heating, just enough to keep the rice at a comfortable serving temperature. Cook sets the high power heater on. The thermostat trips just above the boiling point of water. The theory being, that when the water is all gone, the temperature will rise above boiling, and, so it's time to turn off the cooker. (Rather genius in its simplicity.)

What I think might be happening, is that there is some kind of electromagnet that keeps the cooker in cook mode as long as the temperature is too low. When the temperatures reaches the cut-off-point, I think current is cut off to the electromagnet, and the switch springs back into the warm mode.

In light of the principle of operation I lined out, it makes no sense for a thermostat, if that the mystery component was, to be in series with the entire device. If that were the case, how would it ever enter warm mode?

No, I must go with thermal fuse, if the component is thermal in nature at all, which I simply don't know if it is right now.

Reply to
Per von Zweigbergk

I was able to fix it. Working under the assumption that the failed component was a thermal fuse, I figured there was no harm in shorting together over the thermal fuse, except for a risk of overheating.

So, I shorted the fuse leads together, and the device appeared to function normally, so I went out to Elfa and got myself a new thermal fuse. Working from the assumption that "170" in fact was the maximum temperature in Celcius, I replaced it with the closest value available,

184 degrees.

The rice cooker appears to be functional again. I even checked the current draw, and it seems to be very close to spec.

They don't build these the way they used to any more. Definitely worth the repair. :-)

Thank you for your help.

Reply to
Per von Zweigbergk

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