100s of these, what are they?

[gary350]

I am pulling parts from 8 different TVs so I can trash the circuit boards and free up some valueable floor space.

All the TVs have these. They are all same body color, same 2 black rings, they all test 0 ohms, they test 0 inductance and 0 capacitance.

They are all magnetic. The body stick to a magnet like it is made of steel but the wire in none magnetic. I assume they are a ferrite material on wire.

On average circuit boards have 30 to 60 of these per board. They are the same size as 1/2 watt resistors.

What are they and what do they do???

**broken link removed**

 

[DerStrom8]

I am pretty sure those are indeed resistors. They are probably attracted to the magnet because of the leads.

You can tell for sure by looking at the bands, and then measuring them for resistance with an ohmmeter.

 

[JimB]

Two possibilities I think:

Wire links, ie zero ohm resistors. Probably magnetic because the wires are iron (cheaper) rather than copper.

Or

RF Chokes, a ferrite bead on a wire link. The magnetic property could be due to the wire, the ferrite, or both.

As you have lots of them, and they cost very little, try scraping the coating off one of them and see what is inside.
Post a picture when you have done scraping, enquiring minds need to know.

JimB

Afterthought, if these are just wire links, they are probably built like resistors so that when the circuit board is built, the component just looks like any other resistor to the automatic board stuffing machine and so is easy to handle.

 

[DerStrom8]

Wire links, ie zero ohm resistors.

If you look very closely they have different colored bands, for example I see a red-black-black, which would be a 20 ohm resistor. Jumpers (zero-ohm resistors) generally just have a single black band right around the middle.

 

[Menticol]

EDIT: Sorry, post got updated while I was writing

 

[JimB]

OK Mat, on closer examination I see that there is a difference in the marking.
Gary has said that they measure zero ohms, assuming that his meter would display 10 or 20 Ohms OK, I would be inclined to say that they were inductors, red black black maybe 20uH ?

If Gary can scrape one naked we can get a better idea.

JimB

 

[cowboybob]

They all look Black - Black - Gold, to me. For what that's worth...

 

[tvtech]

I guess little 20 uH Inductors. Too fat for Zero Ohm Links.

 

[fezder]

couldn't those be tested with signal generator and scope to see how they behave at high frequency? that would give pretty good indication whether they are resistors or inductors....just saying!

 

[DerStrom8]

OK Mat, on closer examination I see that there is a difference in the marking.
Gary has said that they measure zero ohms, assuming that his meter would display 10 or 20 Ohms OK, I would be inclined to say that they were inductors, red black black maybe 20uH ?

If Gary can scrape one naked we can get a better idea.

JimB

Sorry Jim, I missed parts of his original post.

Looking even closer (I zoomed in all the way on the image) I think they are all black-black-gold. I've never seen two black bands used to indicate a 0-ohm resistor, but it definitely looks like that's what they are. Maybe they are just jumpers.

Sorry for the mistake.
Regards,
Matt

 

[JimB]

couldn't those be tested with signal generator and scope to see how they behave at high frequency? that would give pretty good indication whether they are resistors or inductors....just saying!

Exactly!
That is what I would do, but, I do not know if the OP has that type of test equipment.

JimB

 

[fezder]

I do not know if the OP has that type of test equipment.

that thought also crossed my mind, but they are after all, pretty standard equipment....crt scopes are dirt cheap (ebay and likes) and signal generators too, heck, they can be build! at least i saw one, can't remember where thought/or have any experience for that matter...
oh, and i still haven't managed to build that mine inductor tester, remember? was ''stuck'' on current setting-situation, i mean to increase/decrease current as needed....

 

[gary350]

Here are the results of my CSI invistigation.

The body has 2 black rings. Spacing between rings appears to be random but about 50% are very near the same spacing. 1 ring always appears wider than the other ring but there are some rings that are the same width. Out of 100 parts 4 parts have a gold ring and 9 parts have another ring that appears to be very pail color gray or it could be very pale silver or gold color.

With the covering removed there appears to be a dumb bell shape ferrite center with a 10 turn coil of #27 wire wound in the center of the dumb bell. Makes no difference what the rings are, 2 black only, 2 black with 1 gold ring, 2 black with 1 gray ring, 2 very close spaced black rings, 2 very wide spaced black rings, they ALL have 10 turns of .014" diameter enamel coated copper wire wound in them. The copper wire is soldered to the wire leads. Wire chart says .014" wire = 27 guage wire. The copper wire measures 2" and about 1/16" long. If I were to straighten the wire perfect straight it might be longer maybe 2" and 1/8" long, maybe.

With the copper wire removed resistance changes from 0 ohms to more than 20 meg ohms on my meter. My meter reads nothing with the copper wire removed. The black ferrite center is magnetic. The leads are not magnetic. I cut some 1/4" pieces from the leads my magnet will not pick them up. Wires must be silver plated copper?

I have learned the hook up wire is not 1 continious wire that goes all the way throught the black ferrite part.

The ferite core is magnetic and has maximum resistance.

The 10 turn coil is in series with the 2 lead wires. The small diameter of the ferrite center is .074"

Look at the photo you can see where the copper wire was soldered to the leads, where the leads connect to the ferrite core.

Now that I know this is a choke/inductor coil I retested it on my lowest H scale of 2mH, I get no reading.


**broken link removed**

 

[fezder]

i'd say inductors....

 

[ronsimpson]

The "drum" makes me think inductor. Ferrite drum.
There is a "wire wound resistor" but the drum is not magnetic.
If these inductors are used at high frequency the values may be so low that your 2mH scale will not read them well.
Also the "o ohm" is a good clue.

 

[Nigel Goodwin]

It's a small RF choke (inductor), presumably just used for supply decoupling?.

But to 'rain on this parade' - if you don't know what a component is, you don't need it

 

[tvtech]

Hiya Fez

What's happening?

Regards,
tv

 

[killivolt]

It's a small RF choke (inductor), presumably just used for supply decoupling?.

But to 'rain on this parade' - if you don't know what a component is, you don't need it

If he's pulled these from the board shouldn't it read "L" and the number of the location? Just as D is for diode R for resistor Q transistor?


kv

 

[JimB]

If he's pulled these from the board shouldn't it read "L" and the number of the location? Just as D is for diode R for resistor Q transistor?

In an ideal world, yes they would be marked like that.
But, it could be that the boards were not silk screened with the component idents, just to save a few pennies.

JimB

 

[Nigel Goodwin]

If he's pulled these from the board shouldn't it read "L" and the number of the location? Just as D is for diode R for resistor Q transistor?

There's certainly no guarantee of that