20 Most Recent Panasonic NN-P295SF Microwave Oven Questions & Answers

If there is spark please do not switch on unless you have confirmed the fault. It is possible that the Magnetron is leaking and sparking to the ground. As you have mentioned it was stored, it is quite possible that insect can get into the oven and create soft spots. When you switch on these will create a short and make the voltage jump and in the long run damage the magnetron. So Remove cover after disconnecting , check for dirt/moisture in the cabin, if so wipe clean and dry, check the magnetron and area clean and use an jet air to clean off. Now switch the microwave power on and use a cup of water to test. If you notice any sparks shut off as the magnetron or the main HT capacitor can be faulty. Replace with same type. If not check the waveguides within the cabin for food particles that can burn and spark, check for rust that can corrode and spark when the ceramic paint has worn out. If there is heating without any issues, you can use the microwave safely

Click on replacing waveguides: http://www.espares.co.uk/advice/microwave/a/5/1146/how-to-replace-a-microwave-guide-cover.html

Don't order a new button. Here's what I did. I have had many issues with my Panasonic microwave ovens - the button more than once. I even ordered two new buttons from a reliable source and one of the boxes had the wrong button inside. Today, instead of ordering ANOTHER button, I fixed it simply with a bolt and washer. Precisely: the button is built with two hooks, two prongs, and a central "tube". I used a #10 phillips head machine screw (bolt) 1/2" - 3/4" long and a #8 washer (plus Loctite: optional). You need to open the washer's hole slightly to fit over the #10 bolt. Then simply put the button and spring on the bezel and install the bolt from the rear. The washer will trap the bolt in the bezel, but pass through the frame to operate the latch.

This will be either a faulty door interlock switch or High voltage component. You will need to remove the outer cover after first disconnecting power. Discharge the high voltage capactitor!
Check the door switches are operating correctly if so move on to the high voltage components starting with the transformer

Call Panasonic (905) 624-5010.

There is a 125V, 20 AMP line fuse inside the microwave. Its usually mounted on a small input line filter board at the point where the power cord enters the back of the unit. You will need to UNPLUG the microwave oven and remove the exterior case to access. The case comes off in various ways depending on manufacture and model. Searspartsdirect.com has some excellent exploded view parts illstrations you can use to assist you in component location and assembly.

If the model number is correct, the fuse is listed as item 55 in this parts illustration:

http://www.searspartsdirect.com/partsdirect/showSubComp.pd?imageUrl=http%3a%2f%2fc.searspartsdirect.com%2flis_png%2fPLDM%2f50029794-00001.png

There are also a couple of thermal cut-outs listed as items 51 and 52. These can affect the operation of the oven as well, but usually are related to overheating something in the oven cavity. If you haven't overheated the oven cavity recently, its probably the line fuse. (Popcorn and Potatoes are notorious for causing overheat problems).


You can purchase repacement fuses for appliances at any hardware store. Just make sure the rating is the same as manufacturer installed fuse. You need to purchase a 125V, 20AMP, slow blow for best results.

To answer your question about the fuse blowing when the unit is not in use...Yes, this does occur. You may have experienced a minor power fluctuation such as a brown out over the night that could have caused the fuse to blow. Some components are more sensistive to variations in current than others.

Another possibility that I have to mention is roaches. This does not in any way insinuate you live in filthy conditons, or have an infestation. I just need to mention that insects (such as roaches) are attracted to electronics. Especially, where there may be food. Since their body composition is mostly made up of water, if they crawl across an electrical component, they could cause a short circuit and blow a fuse.

If you have any questions, or need assistance troubleshooting, please post back and let me know. I hope you find this information helpful.

NOTE: Make sure you take any resistance readings with the microwave UNPLUGGED and the component under test isolated (removed) from the circuit.

You'll need to remove the outer cover to get to the door open button or door lever, either of which can cause this problem.The service manual is here. You can order Panasonic 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.