20 Most Recent Sharp R-1490 Microwave Oven Questions & Answers

A microwave can be dead for many reasons.

The fuse is normally located on the floor of the chassis behind the control panel or between the door switches.

If the fuse is good, it may be an open thermostat or thermal cutout (TCO) / thermal fuse on or near the magnetron or on top of the cavity / body of the oven.

If it goes dead for a while during or after cooking then comes back on, the magnetron is probably overheating and causing the magnetron thermostat to open.

Then when it cools, it closes the circuit and allows power through again.

When checking thermostats, if it has a hood fan thermostat, that should read open, as opposed to the others, which should read closed.

If it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.

If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.

If it goes dead or blows the breaker when you plug it in or open or close the door, then there's a problem with a door switch or door switch mount.

If it's intermittent or random, it may be a bad connection, usually on the control board or a loose fuse holder, or even an intermittent fuse.

You should do a continuity test on the fuse while it's in the holder (with the microwave unplugged, of course) then turn the fuse by hand or take it out and put it back in, then test it again.

If you remove the fuse, then press the meter leads against the ends, it can allow internal contact to be made and make a bad fuse appear to be good.

If you or someone you know decide to look into it, we have critical safety information and disassembly information at our site, and our link is at our listing here on FixYa: http://tinyurl.com/yzjozk

We're happy to help and we appreciate your thoughtful rating of our answer.

That's a worn out waveguide port cover. You'll need to replace it.Years before the internet took off my Sharp R-9A20 had the same problem, I didn't have Amazon.com so I went to a shop that fixed vacuum cleaners, microwaves, etc. He had to grab a sheet of special cardboard and cut it to emulate the old one.Don't use oven cleaners that aren't microwave safe. They eat right through the metalic coating on the port cover that keeps the microwaves from reflecting back into the tube, I suspect that's what is up.

Hi,
Here is a tip that will help you to figure out what is wrong with yourMicrowave Oven....

Basic Microwave Oven TroubleshootingTips

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The microwave oven is not safe to use, the fire has compromised the interior of the oven, if you run the microwave it will start to arc and eventually short out the magnetron, because the white enamel paint has been burned away. If you have holes in the ceiling there is danger of radiation leakage, for safety reasons the oven should be replaced.

Either the fuse is blown or the power supply is fried out. You can use a voltmeter to check

I just search the way the micowave was put together and I found out how to open the side on the door to get to the latch after I open the door I don,t think the latch is the problem the hook for the spring is broken so I think I will replace the door

You have a failed high voltage transformer, magnetron, or high rectifier diode, or possibly both of the last two.

A loud buzz, hum, or groan is usually a shorted high voltage rectifier diode, but a sound like gurgling into an empty coffee mug is one symptom of a failed magnetron, and yet the mag can be bad without that sound.

The service manuals you need are here:

http://031d26d.namesecurehost.com/mwd/r1490_r1491_r1492_sm.pdf

http://031d26d.namesecurehost.com/mwd/r1480_r1481_r1482_sm.pdf

Here are some links you or someone you know can use for test help, but read their safety warnings first:

http://www.gallawa.com/microtech/diode.html
http://www.gallawa.com/microtech/mag_test.html
http://www.gallawa.com/microtech/xformer.html

You can order parts from Encompass here or you can call them toll-free at 866-779-5835.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

This is happening due to either the magnetron, or the Power Diode, or both, is breaking down, under load, then the unit detects the fault condition, & then, for safety reasons, to avoid a fire or explosion, shuts down the system. You need to take it in to be looked at please obtain a "Quote" before proceeding with any work. This way you can decide to repair or replace.

Front doors are attached inside the microwave at the top and bottom of the oven cavity. Top case has to come off using, likely, security torx screw drivers.
Remove the top hinge.
Remove the bottom hinge.
Door falls off.
Replace the front panel of the door.
Reinsert the lower hinge with the door, close and latch the door.
Holding the door firmly to the microwave, tighten the door hinge. Replace the top hinge.
(On some units, both hinges need to be installed at the same time. Use masking tape to hold the lower hinge - makes it easier.)

Here's a link to the instructions for mounting the unit on the wall. Take a look at the section that shows 2 arms protruding out into the microwave where the microwave is secured by a bolt. Have you removed these bolts? If so, the microwave should pull out. Here's the link to the guide:

http://www.microwavedisplay.com/r1490_r1600_r1750_r1870_r1871_r1872_r1874_hood_inst.pdf

Good luck!

We regularly repair these control units for customers nationwide by mail for $39.95 postpaid in about a week or so with a one-year guarantee.

Feel free to contact me directly (and please include your full model number from the tag in or on the unit) or visit our site.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

William E. Miller
[email protected]
http://www.microwavedisplay.com

Is it making a louder than usual; buzz or hum when you try to cook?If so, I would suspect a shorted high voltage diode ore a bad magnetron.-.htmHere are some links you or someone you know can use for test help, but read their safety warnings first:

line-height:normal">mso-fareast-font-family:"Times New Roman"">http://www.microtechfactoryservice.com/diode.html

line-height:normal">mso-fareast-font-family:"Times New Roman""> http://www.microtechfactoryservice.com/mag_test.html

line-height:normal">mso-fareast-font-family:"Times New Roman""> http://www.microtechfactoryservice.com/xformer.html

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UnhideWhenUsed="false" Name="Medium Grid 3 Accent 5"/> UnhideWhenUsed="false" Name="Dark List Accent 5"/> UnhideWhenUsed="false" Name="Colorful Shading Accent 5"/> UnhideWhenUsed="false" Name="Colorful List Accent 5"/> UnhideWhenUsed="false" Name="Colorful Grid Accent 5"/> UnhideWhenUsed="false" Name="Light Shading Accent 6"/> UnhideWhenUsed="false" Name="Light List Accent 6"/> UnhideWhenUsed="false" Name="Light Grid Accent 6"/> UnhideWhenUsed="false" Name="Medium Shading 1 Accent 6"/> UnhideWhenUsed="false" Name="Medium Shading 2 Accent 6"/> UnhideWhenUsed="false" Name="Medium List 1 Accent 6"/> UnhideWhenUsed="false" Name="Medium List 2 Accent 6"/> UnhideWhenUsed="false" Name="Medium Grid 1 Accent 6"/> UnhideWhenUsed="false" Name="Medium Grid 2 Accent 6"/> UnhideWhenUsed="false" Name="Medium Grid 3 Accent 6"/> UnhideWhenUsed="false" Name="Dark List Accent 6"/> UnhideWhenUsed="false" Name="Colorful Shading Accent 6"/> UnhideWhenUsed="false" Name="Colorful List Accent 6"/> 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mso-bidi-theme-font:minor-bidi;}We have the service manual and I have uploaded it to our site for you here.-.htmPlease reply back here if you still need help.We\'re happy to help and we appreciate your thoughtful rating of our answer.

Getting the display repaired is an expensive repair, and may not be economically viable.

However, using the Sarasota Zip Code 34232 on the Sharp website, found:

SUNRAYS AND BABCOCK S
1621 DESOTO RD.
SARASOTA, FL 34234
(941) 358-9999
This is 4.6 mile(s) NORTH WEST from you.
APPLIANCE SERV OF FLORIDA
1629 W. UNIVERSITY PKWY
11/18/1991
SARASOTA, FL 34243
(941) 355-4545
This is 6.1 mile(s) NORTH WEST from you.
DISCOUNT RADIO PARTS
611 9TH STREET W.
BRADENTON, FL 34205
(941) 750-0531
This is 13.0 mile(s) NORTH WEST from you.


To search yourself, try http://www.sharpusa.com/products/FunctionGetService/1,1286,2,00.html

Chances are the blade assembly has come loose on the shaft of the internal cooling fan.

This can be solved with a couple of drops of super glue at the spot where the blade and shaft meet, then allow it to dry for several minutes.

You can find helpful exploded view diagrams and order parts by entering your full model number here.

At our Web site, we have a video available showing how to remove a typical over the range control panel assembly in under 5 minutes.

Then you'll see the cooling fan.

Please let us know what you find.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

That would be a defective secondary interlock (bottom door switch) or its mount.

We have the service manual for this model and have uploaded it to our site here to help you.

You will need the free Acrobat Reader to view or print it in case you don't have it.

Door switch or mount trouble is usually caused by slamming the door or by opening the door while it's cooking without hitting the Stop pad first.

There are plastic mounts inside the microwave which hold the door switches and onto which the door latches lock when you close the door.

The screws on these mounts may be loose. If they get too loose, the switches will not be activated properly.

Sometimes it's a broken tab on the switch holder, allowing the switch to rotate just out of position. This tab can be hard to see, since it is under the bottom edge of the switch.

If you only need a switch, you can order a universal type here for $5 postpaid.

If you think the problem is on the control panel, we repair these nationwide by mail for $39.95 postpaid in most cases.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.