Please help with component Identification

Surely it is R802, a resistor?

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It looks like a spark gap surge suppressor !

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Best Regards:
                      Baron.

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:

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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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?

The big red blob is *clearly* a thermistor.

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Gibbo

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