Component IDed - Help with replacement MOV

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I was hoping that someone could help me identify a component. This is from a hair flat iron. The component overheated when I tried using it in Europe on a 220 converter.

The burnt out component was round and looked like a capacitor, however the circuit board is marked "TNR" in that space. The two leads look to have jumped to leads from the "SCR", which I am guessing is a Silicon Controlled Rectifier?

Anyways, here are the pics. Thanks for your help.


Last Edited: Thu. Jun 21, 2007 - 05:50 AM
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Looks like it might be a MOV transient suppression device.

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Looks like a transorb to me too

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Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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Have a look at this datasheet:

http://www.rockby.com.au/DSheets...

It is for "TNR" MOVs by Nippon Chem-con.

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Awesome! Thanks a lot you guys. How do I determine the requirements of a replacement MOV? The casing on the original one was totally charred. Is there much diffference between a RLV and an MOV?

The device is listed as 120V, 60Hz, 40W.

Thanks again.

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Quote:

Is there much diffference between a RLV and an MOV?

If you mean RLV as a radial lead varistor then it is often a Metal Oxide Varistor with radial leads.

Quote:

How do I determine the requirements of a replacement MOV?

The SCR is in a TO-202 Package So I think the center lead is the anode and the other lead closest to the edge and connected to the MOV is probably the gate.

The MOV should be rated to be "off" unless the voltage exceeds a safe input voltage. The SCR is in a crowbar configuration. Typically there is a fuse that should blow once the SCR latches on.

Quote:

The device is listed as 120V, 60Hz, 40W

Remember that the mains voltage can vary from 110V to 135V so your crowbar should not trigger below 135V.

Hope this gets you started.

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you could also just not bother with it. Leave the solder holes open, and replace the scr if it is fried

you won't get spike suppression, but if you don't care, then there you have it!!

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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If you leave the MOV out then you should also leave the SCR out. The picture is no longer posted (as of this post) but if I remember it correctly the SCR is part of a crowbar circuit with the MOV providing overvoltage suppression. When an overvoltage condition occurs the MOV turns on and current flows into the gate of the SCR which latches the SCR on -- it appears like a short circuit across the input. Usually this blows a fuse on the input voltage supply. So if your input supply doesn't have a fuse or you leave the MOV off then leave the SCR off too.

John

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If you can source an old PC power supply, TV, monitor etc, you might find some suitable MOVs (jgmdesign - a Transzorb(r) is a TVS diode, not a varistor). I think they are usually a 135V rating for a 115V circuit. The other rating for a mov is usually the diameter of the disc or the joule rating. Get one the same size or bigger.

I dare say the scr is a heating controller in this application with the MOV as a protection device. It sacrificed itself to save the hair iron!