Replacing microwave cardboard shield

Posted by aemeijers on October 20, 2009, 6:23 pm

DerbyDad03 wrote:

>> do_not_spam...@my-deja.com wrote:

>>> aemeijers wrote:
>>>> diggerodell wrote:
>>>>> Is the shiny side around the light bulb that illuminates the interior
>>>>> of the oven? If so, replacing it with plain cardboard will be ok, but
>>>>> the light level will be much less. If it is anywhere else, the shiny
>>>>> side may be electrically conductive and part of the microwave system
>>>>> and should not be replaced with plain cardboard. Why not use duct
>>>>> tape to hold the original in place?
>>>> Uh, don't use the fabric stuff. Go get a roll of real duct tape, the
>>>> sticky aluminum kind. It is actually rated for temps as high as the
>>>> microwave box will actually get.
>>> Aluminum foil tape withstands attic heat better than ordinary cloth-
>>> plastic duct tape does, but alumium foil tape is not guaranteed for
>>> high temperatures since its adhesive is often rated for only 160
>>> Fahrenheit, sometimes for 250-300.

>> Not disputing your statements, but aside from what you mentioned around
>> the light bulb, how hot does your microwave get inside? I've had several
>> over the years, and none of them got too hot to touch inside.
>> Never seen a consumer microwave with a visible mica window over a
>> waveguide outlet. All the ones I have ever field-stripped had a plastic
>> top to the cooking compartment, with a spinner above. But in re-reading
>> OP's post, I wonder if you may be right, and they have some older
>> pre-spinner model. In which case I recommend they just live with it
>> while they save up for a replacement. New microwaves are getting
>> absurdly cheap compared to what they were in the old days.
>> --
>> aem sends...- Hide quoted text -
>> - Show quoted text -

>
> re: "Never seen a consumer microwave with a visible mica window over a
> waveguide outlet."
>
> My Sharp Carousel has one.
>
> I've replaced it numerous times over the years, originally by spending
> too much on a original replacement part, more recently by buying a
> sheet of mica material from a local appliance repair shop. Now I cut
> my own.
>
> They get food splattered on them, which burns a hole in them and then
> the spraks start flying.
>

Hmm. Learn something every day on this here interweb thing. Guess my
sample size of a couple dozen personal, relatives, and resurrected
dumpster microwaves was too small.

--
aem sends...

Posted by Tony Hwang on October 19, 2009, 9:49 pm

diggerodell wrote:

> Inside my microwave is a small 3x5" opening which is covered by a 3 x 5"
> piece of thin shinny cardboard. At one time, the four corners of the
> cardboard fit snugly into four small slots, so that it barely covered
> the full opening. Now those four corners have become broken and worn,
> allowing the cardboard to slip 1/4" below the top opening. Will this
> affect the performance or safety of the microwave? If so, can I replace
> the cardboard with a piece of non-shinny cardboard?
>
> Thanks.
> digger
>
>

Hmmm,
How about holding cardboard with a drop of epoxy?

Posted by on October 19, 2009, 9:54 pm

diggerodell wrote:

> Inside my microwave is a small 3x5" opening which is covered by a 3 x 5"
> piece of thin shinny cardboard. At one time, the four corners of the
> cardboard fit snugly into four small slots, so that it barely covered the
> full opening. Now those four corners have become broken and worn, allowing
> the cardboard to slip 1/4" below the top opening. Will this affect the
> performance or safety of the microwave? If so, can I replace the cardboard
> with a piece of non-shinny cardboard?

I strongly suggest you post a photo because there are several openings
in a microwave cavity:

1. door

2. steam/fumes vent

3. magnatron duct: A metal duct running from the microwave-generating
magnatron to the interior of the oven. This is covered by a piece of
mica to keep the duct clean of food deposits. However the mica is
transparent to microwaves. The mica resembles cardboard and is
silvery-white when new but discolors from food as the oven is used.
Don't run the oven without this cover in place, and don't substitute
anything for mica.

4. interior lightbulb window: Usually a series of small holes (1/8"
to 1/4" diameter) to block microwaves, and there may be a metallic
reflector behind the bulb. If you replace the reflector with anything
but the original part, be sure it can withstand the heat (bulb can get
very hot) and will not short against the lightbulb metal bottom or the
wiring. Aluminum foil tape may be suitable here, but, contrary to
another post, it is not necessarily made to withstand high heat since
its adhesive may be rated for just 160 Fahrenheit. Some aluminum foil
tape has adhesive rated for about 250-300F. If aluminum foil tape
comes undone, it could slip and short.

Posted by Oren on October 19, 2009, 10:28 pm

On Mon, 19 Oct 2009 18:54:36 -0700 (PDT), do_not_spam_me@my-deja.com
wrote:

>diggerodell wrote:

>> Inside my microwave is a small 3x5" opening which is covered by a 3 x 5"
>> piece of thin shinny cardboard. At one time, the four corners of the
>> cardboard fit snugly into four small slots, so that it barely covered the
>> full opening. Now those four corners have become broken and worn, allowing
>> the cardboard to slip 1/4" below the top opening. Will this affect the
>> performance or safety of the microwave? If so, can I replace the cardboard
>> with a piece of non-shinny cardboard?

>I strongly suggest you post a photo because there are several openings
>in a microwave cavity:
>1. door
>2. steam/fumes vent
>3. magnatron duct: A metal duct running from the microwave-generating
>magnatron to the interior of the oven. This is covered by a piece of
>mica to keep the duct clean of food deposits. However the mica is
>transparent to microwaves. The mica resembles cardboard and is
>silvery-white when new but discolors from food as the oven is used.
>Don't run the oven without this cover in place, and don't substitute
>anything for mica.
>4. interior lightbulb window: Usually a series of small holes (1/8"
>to 1/4" diameter) to block microwaves, and there may be a metallic
>reflector behind the bulb. If you replace the reflector with anything
>but the original part, be sure it can withstand the heat (bulb can get
>very hot) and will not short against the lightbulb metal bottom or the
>wiring. Aluminum foil tape may be suitable here, but, contrary to
>another post, it is not necessarily made to withstand high heat since
>its adhesive may be rated for just 160 Fahrenheit. Some aluminum foil
>tape has adhesive rated for about 250-300F. If aluminum foil tape
>comes undone, it could slip and short.

Posted by diggerodell on October 20, 2009, 10:43 am

By process of elimination, the opening I've described is clearly #3 in
Oren's list of 4 possibilities. Rather than replace it, I may try to use a
very small piece of aluminized duct tape to reinforce the two corner points
so that the mica cover would fit snugly in the two bottom grooves and cover
the entire opening.

THANKS! digger

> On Mon, 19 Oct 2009 18:54:36 -0700 (PDT), do_not_spam_me@my-deja.com
> wrote:

>>diggerodell wrote:

>>> Inside my microwave is a small 3x5" opening which is covered by a 3 x 5"
>>> piece of thin shinny cardboard. At one time, the four corners of the
>>> cardboard fit snugly into four small slots, so that it barely covered
>>> the
>>> full opening. Now those four corners have become broken and worn,
>>> allowing
>>> the cardboard to slip 1/4" below the top opening. Will this affect the
>>> performance or safety of the microwave? If so, can I replace the
>>> cardboard
>>> with a piece of non-shinny cardboard?

>>I strongly suggest you post a photo because there are several openings
>>in a microwave cavity:
>>1. door
>>2. steam/fumes vent
>>3. magnatron duct: A metal duct running from the microwave-generating
>>magnatron to the interior of the oven. This is covered by a piece of
>>mica to keep the duct clean of food deposits. However the mica is
>>transparent to microwaves. The mica resembles cardboard and is
>>silvery-white when new but discolors from food as the oven is used.
>>Don't run the oven without this cover in place, and don't substitute
>>anything for mica.
>>4. interior lightbulb window: Usually a series of small holes (1/8"
>>to 1/4" diameter) to block microwaves, and there may be a metallic
>>reflector behind the bulb. If you replace the reflector with anything
>>but the original part, be sure it can withstand the heat (bulb can get
>>very hot) and will not short against the lightbulb metal bottom or the
>>wiring. Aluminum foil tape may be suitable here, but, contrary to
>>another post, it is not necessarily made to withstand high heat since
>>its adhesive may be rated for just 160 Fahrenheit. Some aluminum foil
>>tape has adhesive rated for about 250-300F. If aluminum foil tape
>>comes undone, it could slip and short.

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