The light in my GE microwave quit coming on so after pulling the case apart
to get at it (great design, guys!), the filament of this 25 watt plug in
bulb looks intact. However, a meter across the two male terminal spades
shows no continuity.
There's power at the connector supplying the light when the door is open or
the oven is running-- so that's not the problem. Could the bulb be bad even
when it shows continuity?
You are asking if a burned-out bulb is bad? This is why I don't believe in
If you stick it in another (more portable) lamp and flick it with your
fingernail while it is on sometimes the filament will reconnect and weld
itself back in place. This, of course, works better with DC than with AC.
I have fixed many incandesant bulbs this way.
Hmmm... I re-read it and it looks like you asked if a bulb does not light up
and shows no continuity... obviously I'm missing something here... maybe I
decended from the other race of humans :-|
Parts guy was stumped by the intact filament/no continuity too (see Van's
post). But I decided to try a new bulb (for $11.24.
It shows continuity.....and works. Thanks to all for the helpful
Just because you the break was visible doesn't (obviously) imply it
was/is intact. Nor, of course, that the fault could be at the
connection of one end of the filament to the base, etc., ...
When it doesn't light and measures open, it's pretty clear it's defective.
Bulb is 25 watt, tubular, about 2 inches tall, integral plastic base with
two blades protruding beneath that slide into female connector.
The filament is circular going around the circumference of the glass and is
supported by 5-6 separate wire posts -- each topped with a loop to
support/lock the filament wire.
The parts people only had a 20 watt, about 1 1/2 inches tall. That's the one
I bought and put into the microwave.
No reason a 79 cent standard appliance bulb couldn't have been designed into
it originally-- but then again, these are the same guys that forced me to
take the entire sheet metal cover off. Good thing I had the right bit to
remove the 6 locking torx screws they used to fasten the case.
It's really ridiculous they way so many products are designed by graduate
engineers using custom/proprietary parts and sub assemblies when standard
parts would do just as well. Adds cost, complexity, assembly errors--- and
no real benefit to the end user.
<edit down story of hard-to-replace bulb to reduce line count>
It appears to me that microwave ovens are designed to impair consumer
repairs - for liability purposes.
It also appears to me that choice of lamp type is on basis of
reliability, and in part from microwave oven design engineers being more
conservative types more likely to give higher weighting to reliability and
It appears to me that such type engineers would choose incandescent over
LED because LED lighting has had a lot of overblowing and hype, and
because many white LEDs fail to last as long as their proponents claim.
I have seen it to be common practice for incandescent lamps in microwaves
to be run at reduced power to extend their life expectancy, so that
chanceas are good that the light bulb will not need to be replaced
during the life of the microwave. This appears to me consistent with
reliability and safety including reduction of repair attempts by
I suspect that some microwave ovens will soon come out with LED interior
lighting, now that there are some white LEDs with actual good expectation
to last 30,000 or 50,000 operating hours with only minor to moderate
It should not take too much to protect the LED(s) from the microwaves.
I suspect the main hurdle is the extensive testing of something so new
and different by a safety certifcation laboratory institution such as UL.
- Don Klipstein ( firstname.lastname@example.org)
Many folks don't realize that very bright LED modules
require heat sinks to be reliable. I'm sure a perforated
screen like what's in the glass door can block microwaves
from the electronics of the LED lighting but heat may be
a factor too. Heck, old microwave ovens are a great source
for parts for us mad scientists.
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