Micro displays POWER FAILURE when started or at end of cook cycle

This problem is almost always due to a defective or loose magnetron causing electrical interference and disruption in the control circuit board.

This is most common on models made by Samsung (no matter what brand they are) and they will likely have an FCC ID number prefix of "A3L" on the tag in or on the unit.

One way to test it is to do the following:

NOISY MAGNETRON TEST (c) 2009 William E. Miller [email protected] (used with permission by poster, who holds the copyright)

1. Unplug the microwave or turn off its breaker.
2. Open the door, then detach the control panel as shown in the video at http://www.microwavedisplay.com and swing it down, but without disconnecting the wires. )If you have any trouble getting the grille off once the screws are removed, slide the hood vent grille to the left about 1/4", then then pull it forward. On some models there are L-shaped clips that fit into a slot to hold bottom of the vent.)
3. Plug the microwave back in.
4. Make sure neither you nor anyone else reaches in behind the control panel. There will exposed high-voltage connections.
5. Put a few cups worth of water in a microwave-safe container and place it inside the microwave.
6. Shut the door.
7. Run the microwave for about 1 minute or so on full power. (Time Cook > 1 > 0 > 0 > Start, e.g.)
8. If it does not fail, try it several more times.
9. When the water boils, change the water and try again.

NOTE: If your model does not have a door handle, you will need to unplug the oven and reattach the control panel to be able to open the door.

If it still does not fail, I would recommend that you put it all back together and keep using it until it fails more consistently, then repeat this test.

While a microwave should never be left running unattended under any circumstances (as your owner's manual will tell you) it's even more important when one is exhibiting a failure or any odd behavior. So play it safe and stay with it while it's running!

If you or someone you know want to replace the magnetron yourself, you will need to remove the oven from the wall.

If so, the installation instructions are very handy, and it's best to have two people since the microwave can be heavy and awkward.

You can download owner's manuals and installation instructions for several brands (including Amana, Jenn-Air, Kitchenaid, Litton, Maytag, Roper, Tappan, Thermador and Whirlpool) here.

There should be a "mini-manual" (tech sheet) hidden inside the unit behind the control panel or hidden on the left side behind the grille, which is very helpful when troubleshooting, testing, and locating components.

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.

You can find links to helpful exploded view diagrams and part ordering help here.

I'd recommend that your bookmark this link to your favorites.

If it's within the magnetron portion of the warranty (usually 5-9 years) but out of the original full warranty (usually 1 year), then your manufacturer will cover the part cost, but not the cost to visit you or the labor charge to do the work.

If you prefer to arrange service by an authorized service center, Whirlpool customer service is here.

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