Cuisinart coffe make part identity help

I should have added that the component is radial lead, with blue plastic coating.

And.............the component is connected/tied across the hot and neutral of the main 125V supply.

On Thu, 29 Jan 2009 13:06:16 -0800 (PST), snipped-for-privacy@cox.net put finger to keyboard and composed:

ZNR usually denotes a Metal Oxide Varistor (MOV). Its diameter is an indicator of its energy rating (Joules). IIRC, a 240VAC system usually has a 275V MOV. Your mains supply might use a 150V or 175V device.

- Franc Zabkar

On Fri, 30 Jan 2009 11:09:47 +1100, Franc Zabkar put finger to keyboard and composed:

ZNR = zinc-oxide nonlinear resistor

- Franc Zabkar

Thanks for the info Franc. What I still don't understand is why it is configured so that the coffee maker would still work with this component blown. I guess it did protect the rest of the circuit, even though two traces were blown off.

MOVs (Metal Oxide Varistors - basically a voltage-variable resistor) are intended to protect against overvoltage. As the voltage across them exceeds the breakdown voltage rating of the device, it switches over into conduction, basically close to a short circuit. You will sometimes see a fuse in series with the power lead - when the MOV goes into conduction, the fuse will blow, protecting the rest of the circuitry from the overvoltage. If there's nothing but the MOV across the mains, as soon as it self-destructs from overcurrent, there's nothing left to protect the downstream components.

Feel free to correct me if I have any of this wrong. I have been practicing the software dark arts for the last 20 years - far removed from my EE days.

Jerry