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Repair guides and information for rice cookers.

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Power fuse got blown when inserting into wall

I have a japanese rice cooker with the brand name being panasonic SR-MY051 and i am trying to locate the fuse that got blown but im slightly new to this type of stuff so my experience in locating the correct component isn't too great. When the fuse it on the board, on the board itself it says "ZNA" not sure what that stands for but i assume it is the failsafe incase of something like this happens.

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@choukosenpai the "ZNA" is actually ZNR. Check the letter for the Resistor R80. Identical font. ZNR actually is a component. ZNA used to be a manufacturers code for a diode, which this component definitely isn't :-)

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@choukosenpai interestingly enough the component that looks damaged, is actually the one that is labeled "ZNR". It is a ZNR surge absorber and functions like a MOV varistor. Panasonic came up with the ZNR for Zinc-Oxide Non-liner Resistor. If at all possible take another picture from the side (straight on is always better than angled). and see if there are any markings on that component. Otherwise check on here and see if you can match it by the dimensions and your rice cookers voltage. As for the fuse, it is as @jayeff described.

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im looking at mouser but there is a quite a few ones that exist there, how would you know what rating would be the correct for the board?

the fuse that @jayeff mentioned seems to be okay without issues. the main reason for the ZNR to blow like it did was because i tried to plug in the rice cooker into a european outlet via a converter but it most likely was not set up correctly. i have heard that it is possible to change how much the board should be able to take (current) wise, though i am not too sure if it even is true.

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@choukosenpai

The voltage/current ratings of MOVs (can also be called surge protector) are selected to work with the mains supply values for the areas in which the device is sold.

If the board (or device) was able to work with multiple voltages it would be designed to cater for this and usually a good indicator is that the product label would specify the voltage e.g. 120V AC or 240V AC or if dual voltage (which covers most main supplies it would show 110- 240V AC.

It would require an redesign of the circuit for it to be able to work with a different voltage.

The only way really is to use a step-up or step-down transformer power supply and connect that between the supply and the device.

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@choukosenpai click on the link in my answer and take the dimension from your damaged component. It will definitely get you in the right ballpark. Ones we know the Panasonic "number" we can most likely find a match. Once you have your board fixed, consider using a down-transformer to use your rice cooker or try to find a board that uses the higher voltage and fits your cooker. It'll be easier then to redesign yours,

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Hi @choukosenpai

The fuse on the board is a timed (aka slow blow) fuse as shown by it's marking i.e. T3.15A 250V - see image below.

The T = timed.

When the power is first connected the inrush current is several times more than the current needed to operate the device. This current lasts for approx 5-10mS and then subsides. A normal fast acting fuse having the same current/voltage specifications would blow immediately but timed (aka slow blow) fuses are designed to hold until this current subsides.

Search online for T3.15A 250V Miniature Round Slow Blow Fuse to find suppliers. (examples only)

If the fuse is blown i.e. tests OL or open circuit, there's always a reason for this to occur as normally fuses don't fail of their own accord. So perhaps buy two or three fuses as you may need them in case the first blows as soon as power is applied. You'll then have to find out why this happened.

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i see! thank you very much, from me taking a look into the board again the fuse that you mentioned looks to be alright with no visual damages so i believe it should be fine to keep it as it is. Though the ZNR absorber is the one that definitely needs to be changed. Though i am not sure what kind of voltage i should be looking for.

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@choukosenpai

It may not be visually obvious that the fuse has blown

Use a DMM (digital multimeter) Ohmmeter function and test it electrically.

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