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I am trying to find a replacement for what appears to be a ceramic capacitor. However, after trying the numbers on the component in google, I have had no luck at finding an identical or equivalent component.

Apparently there is some kind of identification convention for ceramic capacitors, but the markings on the component don't seem to follow the convention.

So I am not sure what to do from here. Is this not a ceramic capacitor, or is there another way to read the markings on the component?

 

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On the circuit board where this component was located, was it labeled? Like C12, or some such? If so it is a capacitor. I have also seen MOVs that look like this.
 

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Discussion Starter #6
Thanks for all of the replies you guys.

On the circuit board where this component was located, was it labeled? Like C12, or some such? If so it is a capacitor. I have also seen MOVs that look like this.
It is labeled as VR1. And it belongs to the circuit board of a DeWalt battery charger.
 

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Thanks for all of the replies you guys.



It is labeled as VR1. And it belongs to the circuit board of a DeWalt battery charger.
Hmmm... VR would either be "variable resistor", or "voltage regulator". It certainly isn't a variable resistor. I'm not sure if a two-pin regulator exists, or can exist. Well, I take that back. A zener diode is sort of like a two-pin shunt regulator. Could this be some sort of shunt regulator?
 

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Inphase VR is probably:

http://en.wikipedia.org/wiki/Varistor

Look at the picture on that article... I think that's it... so it's an MOV.


Oh and the good news is you don't have to replace it to make the thing work. The bad news is that replacing it won't make your thing work if it's not working now.
Yeah, it didn't dawn on me that VR might mean "varistor". I was thinking of "varable resistor" as in potentiometer, which it certainly isn't:laughing:
 

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Discussion Starter #10
Inphase VR is probably:

http://en.wikipedia.org/wiki/Varistor

Look at the picture on that article... I think that's it... so it's an MOV.


Oh and the good news is you don't have to replace it to make the thing work. The bad news is that replacing it won't make your thing work if it's not working now.
Alright, that seems to be it.

I had actually stumbled upon that wiki article after searching around about MOVs after you and InPhase suggested it. However, after reading the article I had the impression that I could replace the component with just a wire to test whether the rest of the board was operational.

But I guess you are suggesting that the amount of power required to cause damage to this component would surely damage some other components on the board.

Whatever the case may be, I'll replace the component with a wire, just for laughs.

Thanks for the help everyone.
 

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Don't replace the MOV with a wire! It will short out.

The MOV does not conduct normally. What I was saying is that the circuit should work fine with the MOV missing. If it doesn't then you have other problems.
 

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Hmmm... VR would either be "variable resistor", or "voltage regulator". It certainly isn't a variable resistor. I'm not sure if a two-pin regulator exists, or can exist. Well, I take that back. A zener diode is sort of like a two-pin shunt regulator. Could this be some sort of shunt regulator?
MOV= metal oxide VARISTOR. Is not varistor another term for "variable resistor" although it is not a vairable resistor in terms of how I think of a VR?

It would control voltage by bleeding off voltage in excess of its rating or allow current if its rating is exceeded.

just a guess but I would suspect it would allow for an output voltage regulation as the battery is charged. Or, it could simple be a trigger for the led's control as the battery voltage increases, it would allow current to the led to light or inversely to turn off an led.

anybody have a schematic of the charger in question?

and depending on what the MOV is used for, it could cause an overcharge of the battery and subsequent fire is this is a voltage regulator as suggested above. I would not run the thing until its' use is determined.
 

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Discussion Starter #15
Don't replace the MOV with a wire! It will short out.

The MOV does not conduct normally. What I was saying is that the circuit should work fine with the MOV missing. If it doesn't then you have other problems.
Lol, well I guess that's what I get for rushing something involving electricity.

Anyway, it didn't short immediately. Like you suspected another component was broken (just the fuse), so it didn't short until after I circumvented that.
Didn't trip the breaker, but the trace on the board vaporized. Fortunately it was just the trace between the fuse and the MOV.

So, I took your suggestion and left things open were the MOV used to be and the unit appears to work fine now. Although it is outputting 28 volts for a 14.4 volt battery, but that may be normal.

Anyway, I guess I am off to get a fuse and somehow find someone who sells an equivalent MOV.

Problem solved. This is the second time the people on this forum have successfully identified the problem I was experiencing -- doesn't get much better than that.

Thanks for the help.
 

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So, I took your suggestion and left things open were the MOV used to be and the unit appears to work fine now. Although it is outputting 28 volts for a 14.4 volt battery, but that may be normal.

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No, that is not normal. This leads me to believe the MOV is used as a voltage regulator. Many of these charges are multi voltage and Dewalt does have batteries up to 24 volts which your current output would support.

over voltage charges can cause certain types of batteries to explode.
 

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Any decent electronic supply house will be able to identify and cross it to something they have on hand. That burned trace can be repaired with a small wire soldered on each end. Never assume anything.
 
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