Did My Voltage Converter Transformer Burn Out?

Unplug the leads from the switch and connect them directly to each other and see what happens. What do you have to loose?

Hi Guru - do you mean the yellow, red and blue threads? Should I cut them from the solder, then tape them together with electrical tape, then plug the transformer to the outlet?

I am worried about shocking myself - is there a fire hazard also? Thanks.

Don't cut anything. Unplug them from the switch terminals on the back of the switch. Then find the two that come in from the wall and touch them together.

If you don't know what I mean, don't do this. DO NOT touch any bare wires yourself.

Hi Lyn,

When you say "find the two that come in from the wall", you mean the wires that are coming in from the female port on the transformer right? Referring to the picture in the first link I posted, I am referring to the white socket - I see that the red and yellow BOTH come from there and that the blue goes to the plug itself.

Please confirm - thank you so much for your time and help.

I plugged it in and touched the red to yellow. Nothing.

Then, I touched blue to red and I got a spark!!!

What now?

EDIT: I just checked the fuse and it's blown! I have a spare though.

When you complete a live circuit, you will get a spark. You can't see this when it occurs inside the switch. The fact that you got a spark means that you completed the circuit. If the transformer had failed, no circuit, no spark.

I am hesitant to go on. Maybe someone else is willing to take you farther.

OK - but why did the fuse burn out?

Thank you for your help. I am eager to move forward with your help, if you would desire. Would you consider it? I am an avid DIY person and would love to get my hands into this.

Thanks Lyn (or anybody else who is willing to guide me).

This is the first mention of a fuse burning out. What else haven't you told us?

Lyn,

This is not the first mention. I edited my post earlier to include that mention. It blew out when I connected the blue to the red.

I don't believe I have left any other information. The pictures describe pretty much what has happened.

Thanks Lyn.

Sorry, I see the edit now.

Do you have any type of electrical tester?

No I don't....if it's a worthwhile investment, I would consider buying it definitely.

There comes a point in time when you have to realize that your in over your head and take your rice cooker to an appliance repair shop. Not knowing where your located in the world, I would venture that your electrical supply is 220 volts, which can be lethal. You should take a basic electricity course before trying to make any repairs to electric appliances. It's always better to be safe than sorry.

The pictures do not identify all the components. The switch and transformer are easily figured out, but the black block with the yellow wire on the burnt terminal = what?

The switch has three wires attached. What connects to what in all the switch positions, and how many positions are there? (Off/On, Off/Low/High?)

What is the local supply voltage? What do the nameplates in the rice cooker and the transformer module say?

Tornado, the black block (where the yellow wire is connected to) is the outlet where you plug in the appliance, in my case, the rice cooker.

I am in Boston, MA. The rice cooker is from Korea and I can't read the manual but it mentions something about 900W. My transformer was rated for 1000W. I had been using it for 2 years without any problems.

Switch positions are only on and off. Flipping the switch up would be ON (don't know if that makes a difference in relationship to the location of the wires on the switch).

I am attaching a url of the pic of the transformer faceplate - it is also made in Korea and I can't read it but at least you can see the numbers.

http://imageshack.us/photo/my-images/204/5041264597549orig.jpg/

I REALLY hope that the rice cooker has not been fried....that would make me so sad.

Thanks for your help.

X, Unplug the unit from the wall before you do anything. Replace the fuse.

After looking at your pics, I think I figured the switch out. Find a jumper wire and connect the Blue (Neutral Wire) to the Red wire. Leave the Yellow wire alone as I believe this is for the "Power On" light. Plug in the unit and if it is just a broken On/Off switch your rice cooker will once again come to life. You will need to plug and unplug to use the unit. The Pilot light will still work, it is probably a Neon type, maybe an LED. You could find a replacement switch, you need to match the functionality.

Blue Open in off position, On position connects Blue to Red, Pilot is connected btwn Red and Yellow receiving it's power through the fuse circuit and blue neutral.

Good Luck

You guys are playing with fire.

There is no way you can figure out the circuit from the provided pictures. Telling people to connect two wires just to see if it works, and doing this with high voltages is really dangerous!

Get yourself a multimeter. It costs about 20 dollars and you will be able to test the whole thing without putting any live voltages on it. Make sure you get one with a pass though tester. In this mode, when you connect the test leads together the meter will beep, telling you it's shorted (letting the current pass). You can now go through the leads and follow the circuit testing if there is a short somewhere (highly unlikely in your case) or if a connection has blown up. You can test your switch in 30 seconds this way!

Once you have the meter, report back and people will be able to help out a lot better.

Trying to draw out the circuit would help a lot too.

Because of language and differing color codes, this may be tricky to figure out. (If I had it in my hands, I could do some continuity and resistance tests, but the possible combinations are hard to describe.) Ignoring the transformer for a moment, do you have data on the rice cooker itself? Does it have its own switch? If so, you might be able to bypass the transformer altogether by providing a 240-volt outlet for plugging it in directly.

It is strange that the on/off switch has 3 wires attached to it. Does it have an indicator light for the 0n/off status?? If so it can be possible that parts inside the broken switch are creating a short circuit and blow the fuse. If the switch has the "indicator light feature" it will be difficult to get a spare part.

As a step-up transformer from 110 to 240V with a 1KW rating the transformer size in the pictures provided, seems to me pretty small and a bit "underengineered". In my house I have a similar looking step-up transformer but the rating is only 200W. (It survived very short term higher loading of 300W - but I really did not feel comfortable. So a burn-out even after 2 years of operation with a 900W loading seems to me a possibility. And the rice cooker will load the transformer for quite some time - even when the cooking process is not continuously.

Burn-out can only partly be verified with an Ohmmeter as the heat-up during operation could have damaged the wire to wire isolation of the transformer wires. So some windings of the transformer coil can have a short. The shorted internal wires form an shorted "parasitic" secondary coil which can cause excessive current flow (and overload) inside the winding. If you power-up the unloaded transformer this internal high current flow internal secondary winding which will blow the fuse rather fast.

This internal short can not really be detected with an Ohmmeter measuring from the outside connections of the transformer (You might need at least a identical reference transformer or a "windingshort" detector - which can only be used it the iron core of the transformer is removed.).

When you connect the unloaded step-up transformer to the mains voltage (rice cooker not connected) and the fuse will instantly - blow you have this condition.Then you only can throw the step-up transformer to the electronic scrap bin. A repair will not be sensemaking.

Just to clarify some of your doubts..

The switch as shown in the picture is a typical rocker type with a built-in lamp indicator. The third wire is there to complete the circuit and turn that indicator "ON" once the the unit is powered.

In Asian countries, it is very common to find locally manufactured transformers that are of the "auto-transformer" type. It is a practice to that limit or cuts down their manufacturing cost. This is the type of transformer that utilizes the same winding for its primary as well as for its secondary. I believe that's the main reason why the physical size is much smaller compared to an induction type!

Basically you are right regarding the autotransformer design.

but the iron volume and the crosssection are the design key factors. If the core is too small it can easyly gointo saturation and furthermore the core temperature goes up.

We were using a commercial 1KW autotransformer and the weight of the transformer was in the region of 6 kg. Clear you can design the trafo core smaller but if 900 Watts are continuously drawn - it is a risk..

Hi guys,

I appreciate all the responses.

The rice cooker does have an ON/OFF switch.

The switch does have an indicator light (I realize that this was pertinent information - sorry I left it out).

I am gathering from all of the posters that in order to proceed and possibly fix this transformer, I will need an ohmmeter. Will #1 from this list work? Or is it too cheap?

http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=ohmmeter&x=0&y=0

At this point, my thoughts are that I purchase another transformer for the time being and try to learn and repair this older transformer with the help of the people here. I admire all of you for taking the time to explain. It really is interesting for me, all this circuits and voltages and stuff...

Jimh77 - I want to try your suggestion. My question is, is there a possibility that my rice cooker could get damaged through this testing? Also, how do I keep the prongs together? Can I hold them tight with a pair of pliers (rubberized sheath grip)? Is this safe? I don't want to be shocked.

Thank you all!!!

Since you are now living in Boston, there will be no need for a 220/110V transformer for your rice cooker. You a 220V line readily available in your house, use to power your electric water heater, A/C unit and clothes dryer.

Using the existing (special) male and female power connectors from your rice cooker and power transformer box, you can ask an electrician to run you a small power outlet to power your rice cooker directly from the wall. It will be a lot cheaper and safer for you..

Good luck!

Vsar, I am aware that there are certain sockets in a house that provide more power, such as the ones you listed. Unfortunately, I am renting an apartment and don't have the means to do any rewiring.

Thanks for the tip though.

If you are renting, then you have to talk to your landlord, he is more familiar of what is readily available or any limitations in the house. He may also have a readily available staff /electrician that can help you? It is standard here in the States for a house to have both 220/110V power available from the wall. They only differ in the type /shape/ configurations of the wall outlets, which are also indicative of the maximum amperage capacities.

Since it seems that you have a very limited knowledge of electrical circuits, your best bet is to ask and inquire first from your landlord before proceeding further or buying anything!

"A little learning is a very dangerous thing"!! to you and the people around you!

My landlord is very nice but they are dealing with stressful times right now. They just bought a new house and they are too busy fixing it up. I don't feel comfortable asking them at this point. It is news to me that in a regular wall socket in the US, it actually has a 220 current running through it. If that is the case, why doesn't my rice cooker work when I just use an adapter to make the plug fit? There isn't enough power when I tried this...

Thanks Vsar.

the outlet for a clothes dryer or electric stove would have 220vac

you may even have 220vac between the hot legs on 2 different outlets in your apartment

you could potentially figure this out with 2 extensioncords & a volt meter or even by inspecting the breaker panel

the outlets connected to the breakers on 2 different rows in the panel will probably have 220vac potential between them

As I stated earlier, you can easily tell the difference by observation, just looking on how they look as compared tothe most common holes on your walls. The shape, size, hole openings are very different from the regular that are powered by 110 Volts..

Examples shown in here;

www.quick220.com/220_catalog.htm

15 Ampere, 3450 watts
220/240 volt dual straight blade outlet, NEMA 6-15

You need to stop where your at. You do not have the knowledge and skills to safely repair the the converter. Home owner and Renter's Insurance Companies will not cover damage caused by improperly repaired appliances and they will surely not pay for your lose of life. Either buy another rice cooker and set the converter off to the side until you can take some basic electrical courses. Or just buy another rice cooker and forget the rest. ronseto started a thread, Working with Electricity, regarding just this situation. Why take the chance of either a fire or loosing your life? Don't be one of those, who proves Darwin's Theory Correct

Xiaobao12, NO pliers! Use a jumper with aligator clamps preferably booted. Plug in the rice cooker after verifying the fuse is good and power is applied Light will be on.

Turn on the rice cooker and enjoy, just remember to pull the plug to shut it off until you replace the switch.

Jim

Any multimeter digital or analogue will serve.

No special required

well, at least it's not homework ehh

AMEN, but at least with a home work question, they're still working on paper and not live potentially lethal voltages

2nd picture shows clear sign of overheated point if it is the any winding part.

If it is only the connection joint then may not be.

had you taken shot after taken out of the case could get clear view.

Actually you can feel yourself if the overheating sign is all around the winding [even one part of winding] or just a small local area.

Further to my previous reply:

You got a snap while holding the unit in your left hand which indicates it is not more than a KG [2.2 lbs]. which is too less for a 1KVa Transformer [even an Auto-transformer].

Iron core is the primary factor for design.

And Iron & Copper losses be kept as closely equal as possible.

Economically designed transformers may work for time-shared loads but not recommended for continuous loads and keeping on power even without load.

I will take heed of the opinions and buy myself a new transformer.

What do I need to watch out for? Is this a good choice?

http://www.buy.com/prod/1000-watt-travel-voltage-converter-transformer-worldwide-step-up-down/210798611.html

Or should I spend a little more and get this:

http://www.amazon.com/Power-Bright-VC1000W-Voltage-Transformer/dp/B000MX564U/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1320695486&sr=1-1

Thank you for all your help.

If you could give us the voltage and wattage of your rice cooker, we could better advise you on what choice to make on a transformer. I'm glad to see your heeding the advice and going for a new transformer.

I found a manual for a similar model by Cuckoo (the manufacturer). Keep in mind that this manual is for an American model. My model is Korean and therefore, has the voltage that is used over in Korea / Japan.

http://imageshack.us/photo/my-images/593/captureiuf.jpg/

Thanks DJ.

Can anybody shed some light on my question? I just want to run it by the pros before buying another one.

Thanks a lot!

more like this

http://www.amazon.com/Power-Bright-VC2000W-Voltage-Transformer/dp/B000MXW85A/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1320841759&sr=1-1

or

http://www.amazon.com/TC1500-STEP-DOWN-TRANSFORMER-1500W/dp/B000AY3JEK/ref=sr_1_cc_1?s=home-garden&ie=UTF8&qid=1320841507&sr=1-1-catcorr

the rice cooker is going to draw full power for extended periods, so you want an oversized up converter

1.5-2 times the current would not be extreme

a normal 120vac outlet would be rated for 1800watts, hopefully all the connections for the branch circuit you are using are good [safety]

you must really like that cooker to spend nearly the cost of a new one on a converter

After buying or getting the proper type of transformer, still not sure if OP can cook rice!!!

Why not just buy locally available rice cooker?? Example where you can find or get one ready to use.. The OP for sure can eat and everybody will be safe!!

http://www.google.com/search?q=rice+cookers&hl=en&nord=1&biw=1366&bih=655&site=webhp&prmd=imvns&source=univ&tbm=shop&tbo=u&sa=X&ei=k6O6Tq3yFIGA2wWa8ZHVBw&sqi=2&ved=0CMQBEK0E

Amazone has a better item considering input and output connections.

Input has a standard USA socket, [though power cable is not shown] and output socket is a multi-style. And no Adapters required to mate local power cable. Mostly adapter have a continuous cause of trouble of heating at power connections.

The other, Buy.com has a german Power plug and output sockets. You have to use adapters at output; if you can change the input power plug with standard USA plug.

secondly no one has given any further details except Voltage and power ratings, but Amazone item seems to be better.

Have anice time, today and every day!

After buying or getting the proper type of transformer, you are still not sure if you can cook rice!!!

Why not just buy locally available rice cooker?? There are some that are much cheaper than a transformer that will match your application! I am sure you can eat and everybody else including yourself will be safe!!

Example where you can get one ready to cook rice..

http://www.google.com/search?q=rice+cookers&hl=en&nord=1&biw=1366&bih=655&site=webhp&prmd=imvns&source=univ&tbm=shop&tbo=u&sa=X&ei=k6O6Tq3yFIGA2wWa8ZHVBw&sqi=2&ved=0CMQBEK0E

Please please get a qualified electrician to sort this out for you. Think of your own safety and the distress to your family your death will cause!

I will NOT give any advice other than the above.

I guess you missed post #33 where the OP conceded he was in over his head, & is giving up the idea of repair

He is now looking for recommendations for a replacement 110-220 voltage converter

Rather than buying a new transformer check out the price of new rice makers. They are not high priced at all. you will be able to use it anywhere in the USA without worrying about the power requirement.
You are using the transformer at near full power. Even a new one of the same rating will wear out soon in these usage conditions. If there is not an Asian grocery near you check online. There are literally hundred of choices available. Compare the cost of a new transformer with the fittings you need to the cost of a rice maker.

I was thinking the same but was viewing all the replies not to duplicate any given one.

Really it is better to think of buying new one for reasons:

1. The appliance will be fully complient to Local requirements and more safe.

2. Brand new of course is expected to give better service for longer time and may have the warrantee for after-sale service or at least Return policy for a better choice.

Thanks to hajee and all for your recommendations. The rice cooker is my wife's and she loves it. It's a special one because it makes GABA rice - (special way of cooking brown rice so that it releases more nutrients). In addition to that, she got is for very cheap in Korea, compared to how much they cost here.

Hajee, you are saying I should get the Amazon one because it has more options in terms of outlet sizes?

Do I really need to get a 2000W one? Would 1500W be safe? Could that have been the reason why my 1000W transformer burnt out?

Thanks all.

the connections can be problematic

1500 w should be big enough.

shop around, you may find a better price

I understand good rice is important & the wife want's what she wants

Hey guys,

I got this because of the lifetime warranty:

http://www.110220electronics.com/Best-LiteFuze-convertingbox-1500-Voltage-Converter-p/convertingbox1500.htm

Will let you know how it works out...thanks again.

I'm glad we all defer to our wive's desires...

A good choice !

good plan that looks great

Of course the actual user and in our language [Home Government] has to take the right decision.

Have a nice time and tasty blended rice.

I would like to have the recipe or process you make; make public.