Help ID This Component, I think its an Over-voltage Device

tommy; looks like a MOV device rated 150 volt peak, 1 amp perry

My first guess would be a transorb, which is large junction zener designed/rated to absorb transient voltage spikes. The bidirectional (AC) version is simply back to back zener diodes in one package. I believe this is what you have here.

These devices commonly fail short as the transient creates a conductive melt channel through the junction.

If it is from a low level signal input stage, I'd expect the voltage rating to be closer to 15.0 volts but cannot confirm this by PN# cross reference. You could test the other devices with a variable voltage source WITH current limiting (<1mA) so you don't actually FRY the parts.

OK I'm 20 feet from a TEK 370A curve tracer wondering what this part is (don't ask). The input for this unit can be strapped for anything from ± 25 mV to ± 192 VDC and it is in a circuit with one marked V430 MA3A. Here is the V150 with an AC waveform across it, the V430 looks the same but breaks down at 409 VDC.

It looks like you are correct about what the component is. The curves, tolerance, and size all match up with what I would expect. I should have known a MOV wouldn't have that much resistance after it fails.

Thanks for the input!

It looks like 150V back to back connected zener diode rated for 1A. Excess surge voltage with high current will make it short circuited.

MOV will also work in similar way but response will be slow and curve not so sharp. Most probably it is a bi-directional zener diode.

THANKS ALL!

By adding everyones input to my search I was able to find a data sheet in a very short order. Now I can test one of the parts from a spare unit to prove to the customer it meets specs.

If you found the data sheet on-line, could you please post a link to it?

MOVs and TVS diodes are different devices with unique characteristics. Proper device selection depends on the circuit and the type of transient.

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

http://www.vishay.com/doc?49006
http://www.vishay.com/doc?88378

We frequently use devices like the SA150A and it might be viable alternate (repair) part for your circuit.

This is a good news bad news answer I'm afraid. Here is a link to the data sheet:

http://www.datasheetarchive.com/pdf-datasheets/Databooks-3/Book517-33337.html

The bad news is we specialize in obsolescence mitigation for a very specialized industry, most of our work is on equipment from the 60's to 80's. This sheet is from 1977. We procure most of our parts from a select few sources that deal in obsolete parts. Not unusual for us to pay $50 for a pair of op amps I paid $.09 in the 70's.