Please help with component Identification

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Hi, I posted on here a few days ago but so far have no response. I now
have photo's available at http://www.stanleyes.ndo.co.uk/ .

If anyone can ID this component i'd appreciate it.

There is more info in my previous posting "Help Component ID, TVS??"

Thanks
Stan

 

Surely it is R802, a resistor?




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It looks like a spark gap surge suppressor !

 

I'd guess it's a MOV -- metal oxide varistor -- or a close relative,
that as you suspect, is a transient voltage suppressor. The symbol on
the PC board bottom looks right for that to me. I have no idea about
ratings. You might do a search of MOV/TVS manufacturers to see if any
have components packaged and labelled that way.

Cheers,
Tom

 

I'm going off the bottom of the board. The Z801 is the MOV (big red blob).

The glass casing is odd.

 

Hi HJS,

Have another closer look. When I look at it, it seems clear (bottom
of board picture) that Z801 is further from the relay than R802. On
the top of the board, the "big red blob" is the one closer to the
relay. Therefore, I conclude that the glass-encased guy is the MOV,
or whatever. Either that or work has gotten to me and I've gone blind/
crazy/both.

Cheers,
Tom

 

It is clear that R803, drawn as a resistor, is the "red blob" has the
looks and size of a MOV suppressor and that Z801, drawn as a suppressor
(looks like the removed device) appears more like a glass encapsulated
resistor which appear to be rather rare.
Methinks the placement of the parts are bass ackwards.

 

No, the big red blob is clearly an MOV. I suspect the Z801 ID was moved
because it couldn't be printed where needed. The glass case is
characteristic of a diode or zener, but the inside looks like a carbon film
resistor. Confusing.

Doesn't the R802 ID below line up with the removed unknown part?



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Tom & HJS

Tom is correct, Z801 is the label for the mystery glass cased
component. It is labelled both top and bottom of the board and is
furthest from the relay. Just to be pedantic..you seem to be
mistakingly referring to R802 which is not in the photo's, i think you
mean R803. Also, unless i'm very much mistaken R803 (the big red blob)
is not a MOV but a PTC Thermistor (Posistor). I have removed this from
the PCB and at room temperature it has a resistance of 8Ohm. If i
leave it sat on a heater for a while and retest it had changed to
80Ohm. I believe this 10x range is what you would expect from a
Thermistor/Posistor.( I guess this blows the theory that the red blob
is a MOV and the labels have been switched.)
I think this is pretty standard degauss circuitry, On activating
degauss, relay RL801 closes allowing AC current to flow through the
degauss coil, current flows through the circuit causing heating in the
thermistor, this causes the thermistor resistance to gradually
increases reducing the current flow.... Its just this Z801 i'm not
sure about, it could be functioning perfectly OK but i'm not used to
observing sparks in a component even if they are small and contained.
As you can see on the bottom of the board, the mystery Z801 is
connected across one pair of NO relay contacts. I think this makes it
likely the device is some kind of suppression device.

Robert

Please note the photo's were taken before i removed any components
from the board so the chances that the two components have been
switched are minimal. Also note that the pad layout's match the
components, Z801 pads are in line to match the mystery glass
component, R803 has offset pads matching the offset legs of the
thermistor.

Baron

Was your suggestion tongue in cheek? No offence if not, but the name
sounds too close a match to my previous description for it to be true.
I hope i'm wrong, but searching for "spark gap surge suppressor" on
google returns very few hits.

My thoughts are that it could be:

1. A bipolar TVS. But the glass casing is unusual, i can't find
anything similar on TVS manufacturers websites.
2. A resistor, again in unusual packaging. If its burnt out the
voltage could be causing the sparks seen jumping across the inner
cylinder.
3. Dare i say it "spark gap suppressor"? Who manufacturers such
devices?

Thanks everyone, any more thoughts are gratefully received.
Stan

 

For search terms, try gas discharge and/or gas plasma suppressors

Raychem, Tyco, Littlefuse.

Maybe this will get you going: http://www.mouser.com/catalog/629/457.pdf

Good luck!

John

 

But all of those look like what they are!



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It doesn't look like any MOV I've ever seen. Actually, it looks like
a multilayer chip capacitor (MLCC?) in a glass envelope.

I have no idea how to read the stripes, however. )-;

Thanks,
Rich

 

That pretty much takes care of that - it's a MLCC in a glass package.
Maybe designed to be very lossy, like a whole snubber in one 2-pin part.

Cheers!
Rich

 

it looks like a carbon film resistor in a glass package. That is very
bizarre.


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It doesn't look like anything I've ever seen. Until it is ID'd you've got
me.



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Did you not see the legent on the reverse of the pcb ?

I imagine it must be some kind of breakdown diode.

Graham

 

It's a Sg-Gap sg99b3en.

 

I think that is what i said, that the red thinggie is truly a MOV,
but if you look at the designations at tbe bottom of the board where
there are *no* "space limitations", the R and Z designators are
bass-ackwards.

 

I agree, that glass encapsulation is rare and unusual.
The "most recent" glass encapsulated resistors i saw was about 30 or
so years ago, and those were Victoreen gigohm and up resistors for
ionization chamber electronics and similar very low current tube devices.

 

?? A search on all of that or either half gave nothing.
Whazzit?