Component Identification - Inductor?

[kyleaudio]

I'm working on repairing a plasma TV and I ran into two of the same component that I believe are inductors, but I lifted one leg of each and they both measure open circuit.

The color code is Green Black Orange, which should be 50mh.

What do you think? I just want to make sure that they aren't some odd component thats supposed to measure open circuit.

Thanks,
Kyle

[Andy Watson]

They're labelled "R". I think they are 1M ohm resistors. (I think that is a brown stripe, not orange.)

[mariush]

It looks like the PCB uses prefixes that show the component type .. you see there CX804S for a X type Capacitor , NT801S for that NTC component ( the light green disc) .. so based on this the two are resistors.
At least one of them is clearly labeled RA802S  (the LX ... is the common mode choke near it, L is commonly used for inductors) ... I don't know why the other one is labeled EY818, it could be that the text is actually for the part right under it or hidden behind the NTC in the picture.

[kyleaudio]

Good point about the RA being for resistor, they look unusual for resistors though... If they are resistors, what kind of resistors? I just noticed that the silkscreen under these two looks like a resistor symbol with an oval around it. None of the other resistors on the board have this so there must be something special about them.

The one stripe is definitely Orange, it just didn't show up in the pictures very well.

The EY label is probably something to do with the metal can that goes around part of the circuit that is soldered to the point right next to it.

With this color combo, it could be 50k or 3M ohm.

[kyleaudio]

More info. Here's a picture of the silkscreen symbol on the board. I also scraped some of the paint off of one of them.

[eKretz]

I want to say I've seen the RA marking plenty of times on variable resistance components, but perhaps I'm thinking of RV. Could it possibly be some sort of thermistor?

On the other hand, there are other components on that board that have dual letters in the beginning of their reference designators that don't seem to have any clear meaning - for example, the diodes are marked "DM" and who knows what the M is supposed to mean. Maybe it's as simple as: the component is just a resistor.

[Andy Watson]

Good point about the RA being for resistor, they look unusual for resistors though..

I think they are resistors but there is something speciall about them - hence the oval on the silk-screen.  I would guess that they are special in that they fail safely when under excess voltage, or power. Can you sketch-out the surounding circuit? It would be interesting to know if these are across the mains, or in-line.

[Srbel]

That is Thermistor symbol on the silkscreen.

[kyleaudio]

Hi guys,

I took some time and sketched out the circuit. The two black boxes are the components in question.

I think that you're right that they're thermistors, but these are the only two components with a symbol printed on the board, so I would assume that there's something special about them.

Thanks,
Kyle