Jay
Lv 5
Jay asked in Science & MathematicsEngineering · 1 decade ago

Does anyone know what this electronics symbol is?

It looks like this but the triangles are filled in.(pretend the .'s aren't there. I had to add them to get everything to line up)

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.|/

/|

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It's labled as a resistor on the board and schematic but looks more like a tantalum cap to me. It's in between ground and a deflection coil on a CRT.

Thanks.

Update:

The part looks like it has a small crack in it. It's on the pcb going to the horizontal deflection coil and I'm getting no horizontal deflection(just a vertical line in the center of the screen). I think it may be shorted but I havn't measured it yet. I'd like to replace it but have no idea what to replace it with.

Update 2:

ok. your right. text isn't working. here's a drawing of it...

http://i260.photobucket.com/albums/ii12/jeremy_bur...

Update 3:

Looks like it is a varistor. It's not a schmatic of one I've seen before but I did find an example here...

http://www.mechanical-relay.com/dy05a.html

and more closely on this spanish website.

http://electrofacil.galeon.com/contenido_semicondu...

Also, the horizontal oscillator is providing power to the tube which is getting HV so I'm pretty sure thats not the problem. Everything between there and the coil checks out except this part(which has a crack in it) so I'm pretty sure thats the problem...if it's shorted then the signal would go right to ground. Thanks everyone for the help.

5 Answers

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  • MarkG
    Lv 7
    1 decade ago
    Favorite Answer

    A Transient Voltage Suppression Diode. Acts like two zenerdiodes connected back to back so it conducts only when a predetermined voltage is present. This could be used to suppress the inductive voltage spikes generated by the coils.

    EDIT:

    Another suppression possiblility is a varistor , its symbol is sort like a variable resistor except it uses a rectangle with a line through it vs a zigzag line

    Short circuit protection can also be provided by a PTC (Positive Temperature Coefficient) resistor. The symbol is typically a variable resistor with a circle around it. This component would be in series with the coil and would act like a self resetting circuit breaker. Excess current heats it up and its resistance increases which lowers the current.

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  • 1 decade ago

    I don`t know what the component is but I don`t believe that is what your problem is. The problem is more apt to be in the horizontal oscillator circuit or an amplifier stage between it and the deflection coil. If you have a schematic you can probably locate the problem with a volt ohm meter by just checking for obvious abnormal voltages if you are familiar with trouble shooting electronics circuits.

    The component you described is probably a safety device of some sort to prevent any high voltage build up on the deflection coils. If it is only a safety device then the circuit will still function normally without it. So If you still think the mystery component is at fault lift one of it`s leads and see if the horizontal deflection circuit starts working. If not then the problem lies somewhere else.

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  • Numbat
    Lv 6
    1 decade ago

    VDR or Voltage Dependent Resistor.

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  • 1 decade ago

    I suspect it's a set of sharp points designed to arc over above a fixed voltage, and is used for protection. Don't recall the name for the device now, perhaps it will come to me. Something to do with discharge perhaps?

    .

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  • Andrew
    Lv 6
    1 decade ago

    Drawing things in text never works very well.

    Any of these match the symbol?

    http://9w2bba.files.wordpress.com/2007/08/schemati...

    http://www.mitedu.freeserve.co.uk/Prac/symbol.htm

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