Model number NN-V659 has gone kaput. The instructions say it must only be replaced by a qualified engineer. Surely it cannot be that difficult, is it just a safety matter? Any tips, also source of spare lamp and type/rating. I don't want to take it apart to find the details then re-assemble only to take apart a little later to replace it.
In message , Moonraker writes
NN-V659 bulb brings up a number of hits on google
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I expect it is trivial to do if you can tie your own shoelaces
UNplug and leave for at least 24 hours and then still watch out for a lethal voltage on the big capacitor if the bleed resistor has gone open circuit
As another poster has said, microwaves and combination ovens contain a large high voltage capacitor; usually in a metal can with push-fit terminals and with an internal bleed resistor, which could perhaps fail unless the dielectric material itself is the resistor (by being intentionally just a little bit electrically leaky; don't know if they could do that with modern materials but it would be a clever way to make the thing safer).
The voltage on the capacitor is *very* high, and so is the power (obviously). Most magnetrons want 20,000 or 30,000 volts from what I've seen, and in the circuit they use, about half that voltage will be developed across the capacitor. If the unit was turned on momentarily without giving the magnetron filament enough time to heat up, the capacitor wouldn't be discharged by the magnetron.
You most definitely don't want to poke around inside the case with the power on, and you should always use a highly insulated probe to short across the terminals of the capacitor if there's any risk that it still holds a charge, which it could do for a long time if no discharge resistor existed.
Changing the bulb is not much more difficult than changing an ordinary light bulb. Some replacements may have been designed to withstand a bit of vibration, I've heard, so you want the correct bulb. Some have push-fit terminals and ISTR that some have simple SES bases (small screw-in); others are special designs.
You'll probably have to do that anyway, but taking the case off isn't all that hard on the units I've looked at. Maybe a dozen self-tapping screws. What you DO NOT want to do is to touch anything inside until you're ABSOLUTELY sure it's safe to do so. I have no doubt at all that a good few people have been thoroughly fried by microwave high voltages.
Spares can be found in the usual ways. Usually over-priced.
Thanks Geoff, you were correct,it was easy even though I wear slip on shoes! The spare was bit of a problem, the direct replacement is no longer available, so I went to a local repair shop, they supplied me with a separate holder and lamp that with a bit of manoeuvring fits ok. The plus side is if it goes again I just need to get a lamp, which is readily available. Thanks
Yes, with oddities its easier to replace the holder.
NT
Neat idea
True, and combi oven bulbs are higher temp rated too. But in practice I've found generic candle etc bulbs work fine. They might not last so well if you're in the habit of thumping the machine.
NT
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