Does anyone know what this component is in a circuit board?

[SergioB]

Using a Fluke? If so, OL means OverLoad or unmeasurable infinite resistance, same as an open circuit.

Yes, I'm using a fluke. Sooo what do you think?

 

[Lancie1]

Open circuit, blown fuse or overload device. Replace with nearest similar available equivalent.

If you have a can of "Freeze It", just for giggles you could cool it down to see if it starts conducting again.

Your power supply circuit appears to be low power. Can you determine the rating of the F701 fuse? The bad one would be smaller than F701, most likely.

 

[SergioB]

Open circuit, blown fuse or overload device. Replace with nearest similar available equivalent.

If you have a can of "Freeze It", just for giggles you could cool it down to see if it starts conducting again.

That's what I thought. Why did I narrow into this component? well, all caps also looked pristine and the rest of the diodes seemed to work ok while tested soldered to board. This is the only one that would not conduct.

Anyway, that's the idea, to replace it, but I have not been able to identify what the component is...

I'm on my way out right now, but will test freezing it tomorrow.

Thanks!

 

[Lancie1]

I would replace it with a Bussman or similar Slow Blow ceramic fuse, sized lower in amps below the main fuse F701.

Or if I couldn't find a spare fuse, a piece of very small wire to see where the smoke comes out! You were going to replace the LCD screen anyway, right?

 

[Eric Nelson]

Using a Fluke? If so, OL means OverLoad or unmeasurable infinite resistance, same as an open circuit.

If it's a varistor, then it should have a nearly infinite resistance until it reaches it's clamping voltage.

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

I've never stuck an ohmmeter across one, so I don't know if it would read infinite or not...



-Eric

 

[jrwb4gbm]

The picture in post #9 looks like a silicon glass diode. Do you suppose the part number SG702 prefix "SG" (as in silicon glass) on the circuit would be a clue? Just looking at where the component is located seems like where an ordinary diode would be. I think that the fuse at F701 would be all that is necessary instead of having 2 fuses that close together on the board. It would be nice to have a picture of the reverse side of the circuit board to see how the foil strips interconnect the components.

 

[Eric Nelson]

Just to add to the confusion...

Perhaps the 'SG' prefix stands for 'spark gap'?...

http://en.wikipedia.org/wiki/Spark_gap#Protective_devices

For example, there are components in this schematic labeled SG### which are spark gaps (but with the correct symbol for a spark gap)

http://na.suzohapp.com/service_center/pdf/ktxx14x_sm.pdf (Search the PDF for SG802 and zoom way in)

I would expect a spark gap to have an infinite resistance... :nodi:



-Eric

 

[Lancie1]

Eric, I believe that you nailed it down. It all makes sense now. I see 3 of those SG's in that CRT monitor Schematic #9. I imagine that surge currents and lightning are big problems for monitors.

If that SG701 in Sergio's circuit appeared to be melted, then probably it shunted a large spike to ground, and other parts may have been damaged at the same time.

 

[rootboy]

Just to add to the confusion...

Perhaps the 'SG' prefix stands for 'spark gap'?...

I think that you are correct, especially since it's right next to a MOV.

@OP, Context would be nice. Flip the board over and take a shot of that please.

 

[JesperMP]

Surge absorber, I agree.
here is one that looks a lot like SergioB's:
http://www.ttnet.net/ttnet/gotoprd/ET325/050/0/941303236323338353.htm

(everything seems to be amde in china these days).

 

[sonjacksy]

i think its a pin diode but i am not sure about it, but if you want to know about pindiode read this http://www.princeton.edu/~achaney/tmve/wiki100k/docs/PIN_diode.html

 

[maxketcham]

it's a fuse.

 

[westom]

Anyway, that's the idea, to replace it, but I have not been able to identify what the component is...

Nobody can answer with certainty if the circuit is not also provided. PC traces (the circuit) must be defined to know what connects to what. The part could be damaged meaning its function cannot be measured. It could be a diode, a thermal fuse, a bidirectional avalanche diode, or many other possible device. Defining a schematic (interconnections) is necessary.

BTW, there is no such thing as a surge absorber.

 

[Lancie1]

BTW, there is no such thing as a surge absorber.

It may be misnamed, but that is what the Chinese are calling a spark-gap device that shunts excess current to a ground point.

 

[Goody]

It's no wonder people read these forums and become more confused than before they came.
I read the topic with interest. I didn't know for sure what it was.

Then surge absorber was mentioned with pictures to back it up and I thought excellent work boys in identifying it.

Then after that we still get clever dickies guessing but stating it as 'fact'

New readers don't know who to trust and who not. (sigh)