What kind of resistor is that?

[buchman]

Hi,

In that picture there is some kind of component, it look like a resistor but it's a bit bigger and there is a coil inside.

Who can tell me what that is exactly?

Thanks in advance.

[budm]

Re: What kind of resistor is that?

That is just a small axial lead inductor, looks to connected between two filter cap (+) legs to form Pi filter.
Upload the pictures of the bottom side of the board to verify.
I.E.:
http://www.digikey.com/product-detai...8156-ND/774696

[PeteS in CA]

Re: What kind of resistor is that?

Hmmm, the color bands suggest to me it could be a 1K resistor. An ohm meter should tell the difference - an inductor would probably be an ohm or two at most, while a 1K would be much higher (not necessarily 1K, since it's in-circuit).

[capwizard]

Re: What kind of resistor is that?

I bet you,This is a 1uH 10% tolerance inductor . and circuit look like 9v battery step up power supply for high voltage usage. ex: for Lamp, electric fence.....


http://www.vishay.com/inductors/color-code-calculator/

[redwire]

Re: What kind of resistor is that?

I agree with budm, looks like an inductor. Maybe as the Pi filter.
But the color code is odd brn/blk/red/silver gives 10mH +/10% when typically these parts are ~10uH. Putting an ohmmeter on it will sort it out.
I usually find the power transistor/capacitors are shot in these small AC wall adapters.

[keeney123]

Re: What kind of resistor is that?

Could be either it would depend on how it is connected. Or you could measure it. It is either 1,000 ohms/1k ohms 10% tolerance or 1,000 uH/ 1mH 10% tolerance.

[momaka]

Re: What kind of resistor is that?

This particular green-blue color is typically used for inductors.

The color code could be either gray-red-black-brown (82 uH, 1%) or brown-black-red-silver (1 mH, 10%). I think it's the latter. Looks like it's used as a PI coil between the two caps.

[capwizard]

Re: What kind of resistor is that?

My BAD! my mistake ( , ) with ( . )!!!

1.000uH=1uH 1,000uH = 1muH

momaka you're right brown-black-red-silver (1 mH, 10%)

[buchman]

Re: What kind of resistor is that?

It's a wall cell phone charger. I took this resistor/inductor out of the board and measured for ohms, it indicates approximately 5-7 ohms.
How do I measure inductance?
What parameteres I need to know to buy one like this? I meen, what should I say in the store to the seller?

[momaka]

Re: What kind of resistor is that?

It's a wall cell phone charger. I took this resistor/inductor out of the board and measured for ohms, it indicates approximately 5-7 ohms.

That means it is probably okay. Inductors typically show very low resistance when measured with a multimeter, especially ones that don't have many turns. For this small inductor to have 1 mH of inductance, it means the wire of the windings inside it must be very thin... hence the fairly high resistance you got.

How do I measure inductance?

Well, this might seem like a stupid answer, but... inductance meter!
Of course, those cheap eBay transistor testers will also work. The only problem they have is they they can't measure less than about 10-30 uH. So the inductors you see on motherboard and in power supply output stages will appear as a short-circuit and no inductance on those meters.

What parameteres I need to know to buy one like this? I meen, what should I say in the store to the seller?

You need to know the inductance (1 mH... or 1000 uH if you prefer) and current rating. The current rating will depend on what your charger can output. If it's 500 mA, then you need to get an inductor capable of 500 mA or more. 2x the current rating output of the stated current on the charger is typically preferred. So for a 500 mA charger, use an inductor capable of handling 1 Amp.

My BAD! my mistake ( , ) with ( . )!!!

1.000uH=1uH 1,000uH = 1muH

Didn't even notice it.
I read one intro engineering book a long time ago that said to never use a comma (,) when separating zeros above the thousands range. Reason being that you can easily mistake the (,) with (.). Also not a good idea when working in an international teams (European countries, for example, use comma (,) as the decimal separator).

[capwizard]

Re: What kind of resistor is that?

You certainly are the best.

[keeney123]

Re: What kind of resistor is that?

so what is wrong with the with the charger? What isn't it doing.

[buchman]

Re: What kind of resistor is that?

It doesn't charge the cell phone. I know that it's very cheap and I should buy a new one but, it's kind of a small project to me to raise my confidence ☺
I have a plasma TV (lying in my bedroom for a year) that is waiting to be fixed (I can't find the problem so I thought I would start from something simple).

[keeney123]

Re: What kind of resistor is that?

It doesn't charge the cell phone. I know that it's very cheap and I should buy a new one but, it's kind of a small project to me to raise my confidence ☺
I have a plasma TV (lying in my bedroom for a year) that is waiting to be fixed (I can't find the problem so I thought I would start from something simple).

Actually there are a lot of techs on this site that are very good with trouble shooting tvs.

So the charger itself is not working? In other words it is not putting out the proper voltage when measured by itself with volt meter? ?

[buchman]

Re: What kind of resistor is that?

Actually there are a lot of techs on this site that are very good with trouble shooting tvs.

So the charger itself is not working? In other words it is not putting out the proper voltage when measured by itself with volt meter? ?

It has a led light that should light up when the charger is connected to the wall.
Anyway, I ordered 2 caps and a diode that I believe they are all dead. The capacitor rated 2.7 uf but the DMM shows 8.4uf.
The diode show 0.173 so I believe I am not wrong.

[keeney123]

Re: What kind of resistor is that?

It has a led light that should light up when the charger is connected to the wall.
Anyway, I ordered 2 caps and a diode that I believe they are all dead. The capacitor rated 2.7 uf but the DMM shows 8.4uf.
The diode show 0.173 so I believe I am not wrong.

So did you measure the output voltage of the charger to verify your LED is not bad?

[buchman]

Re: What kind of resistor is that?

So did you measure the output voltage of the charger to verify your LED is not bad?

No. How do I measure inside the plug of the wire of the charger?

[stj]

Re: What kind of resistor is that?

show us the diode & capacitors

[keeney123]

Re: What kind of resistor is that?

No. How do I measure inside the plug of the wire of the charger?

So the charger does not have a connector that connects to the cell phone? The chargers of cell phones I have seen have a connector that connects to the phone. Usually the are round and you can put the + DVM meter probe inside this connector and the - DVM meter probe on the outside of the connector set the DVM to DC voltage range. Make sure the charger is plugged in. The charger will have a DC voltage rating on it. Your measurement should be very close. If the connector is tiny use a small gauge wire to put in the + terminal of the connector. Just make sure you do not allow a connection path between connector terminals so that it shorts out the charger.

[and555]

Re: What kind of resistor is that?

No. How do I measure inside the plug of the wire of the charger?

Simply, soldering a cable to each output (+) and GND, then please measure.
Usually the biggest cap is output.