Can you suggets a 110V MOV? - Page 1
Forum section: electronics / repair

author: Peter Tryndoch
author_rank: Contributor
timestamp: February 06, 2022, 08:37:40 am
content: My Nephew got a fancy 110V Japanese rice cooker and thought all he needed was a plug adapter to plug into 240V.After a brief bang, he decided that Uncle should look at it.The MOV blew it's side off along with any part number that may have been there, as well as a fuseable pcb track.So any idea what value MOV I should get?I'm guessing that a 240V one will not suffice.The cooker is a Zojirushi NS-ZCC18

author: trobbins
author_rank: Frequent Contributor
timestamp: February 06, 2022, 08:43:30 am
content: What mains voltage have you got available? just check wit a suitable part supplier what is available of circa 135vac, but you need to confirm what the part spec is using relevant datasheet.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: February 06, 2022, 09:29:39 am
content: could try get schematic around the point?

author: CaptDon
author_rank: Super Contributor
timestamp: February 06, 2022, 06:01:50 pm
content: 130L10 or 130L20 MOV. But the big question is how are you going to power it in the future??? Those stupid triac converters for 240 down to 120 will blow up the MOV again. Seems like you are S.O.L. unless you happen to own a 1kva step up/down transformer.

author: TimFox
author_rank: Super Contributor
timestamp: February 06, 2022, 06:12:37 pm
content: Note that the normal mains voltage in Japan is 100 V, not 110 or 120 V. Therefore, the original MOV may not be able to withstand 120 V. It certainly won't sustain 240 V.The "plug adapters" for international tourists are just passive connectors that work if the load has a universal 120/240 input range.Some crappy ones use a series diode to decrease the RMS current by a factor of 2 (half-wave rectification), but don't change the peak voltage at all.

author: CaptDon
author_rank: Super Contributor
timestamp: February 06, 2022, 06:32:02 pm
content: There has been so much electronics equipment blown to smithereens by those '1.5Kw' voltage converters you can hold in the palm of your hand!!! Whether the diode half wave type or the triac duty cycle limiting (dimmer) type anything but a space heater usually goes boom with fireworks and smoke. The more recent devices using universal switched mode power supplies fair much better. Warning, U.S. travelers coming to Iceland, check the power specs on your device before you plug it in. We could probably fill a volcano with all the blown 120vac transformer or motor powered devices brought from abroad!!

author: Peter Tryndoch
author_rank: Contributor
timestamp: February 07, 2022, 06:54:56 am
content: Being somewhat of a hoarder, I do happen to have a 240 to 110 1kva transformer.It's beast! Weighs 20kg.The unit is rated at 1kw, although a rough calculation by measuring the DC resistanceof the heater coils: P = Vsqd / R came out at 860w.Either way I think the 1kva transformer should suffice.The cooker is made for the US market, so it is 110V and not 100.The control circuit runs off a capacitor dropper.I expected something a little bit better given the price of this unit,but it is what it is.BTW I'm from Australia, so I'll play it safe and say 240V mains at the socket.I'll get some 130L10 or 130L20 MOVs.For the blown PCB track I'll solder in some suitable fine wire.I spent an evening online but could not find a schematic (not surprised)The manufactures web site did not offer one either,and spare parts on offer were only things like bowl, spoon and the like.Thank you all for your help - much appreciated.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: February 07, 2022, 07:25:57 am
content: When MOV subjected to stresses above its ratings, it can breakdown / fail as a short circuit. If applied to significantly exceed the energy rating of the device, and current is not limited, the MOV may be completely destroyed, which could be open. The 240V one may withstands max ~ 600V peak, 424 ACV rms

author: CaptDon
author_rank: Super Contributor
timestamp: February 07, 2022, 03:31:47 pm
content: Yes, he could use an MOV rated for use on 240vac mains, but that doesn't solve the issue of the appliance being designed for the 120vac U.S. marketplace. Thanks for playing.