Frigidaire FFMV1745TS Magnetron Replacement – Step-by-Step Guide

Magnetron Replacement Guide

If your Frigidaire FFMV1745TS over-the-range microwave has lost its heating function and food stays cold, it’s likely that the magnetron has failed. This component is responsible for generating the microwaves that cook your food, and let me tell you, replacing it is an ADVANCED repair. It involves working with high-voltage components, which can be tricky. However, for experienced DIYers, this is a repair you can tackle yourself.

⚠️ CRITICAL SAFETY WARNING

This repair entails dealing with HIGH VOLTAGE components that can be LETHAL. The magnetron operates at over 2,000 volts. You MUST:

• Unplug the microwave and wait at least 60 seconds
• Discharge the high-voltage capacitor before touching ANY components
• Wear insulated gloves rated for high voltage
• Keep one hand behind your back (this helps prevent a current path through your heart)
• Use a discharge tool to safely discharge the capacitor
• If you’re uncomfortable with high voltage, call a professional

Symptoms of Magnetron Failure

Here are common signs that indicate magnetron failure:

• Microwave runs but food doesn’t heat or stays cold
• Humming sound but no heating
• Sparking or arcing inside the microwave cavity
• Burning smell during operation
• Microwave shuts off after only a few seconds of operation

Parts Needed

• Frigidaire 5304521745 Magnetron (Part #: 5304521745)

Note: Magnetrons can be pricey ($150-300). Make sure to confirm that the magnetron is the issue before purchasing, as other components may cause similar symptoms.

Tools Required

• Digital Multimeter – For testing components
• Phillips Screwdriver Set – Various sizes
• Needle-Nose Pliers – For wire connections
• High-voltage discharge tool – CRITICAL for safety
• Insulated gloves – Rated for high voltage
• Safety glasses – Protection from debris
• Flashlight – To see inside the case

Step-by-Step Instructions

Step 1: Unplug and Discharge Capacitor

First, unplug the microwave from the wall outlet. Wait at least 60 seconds — this is CRITICAL because the high-voltage capacitor can hold a lethal charge. Use a discharge tool (like a screwdriver with an insulated handle) to short the capacitor terminals. Touch the tool across both terminals simultaneously. You might hear a pop or see a spark — that’s normal. Repeat this discharge 3-4 times to ensure it’s fully discharged.

Step 2: Remove the Outer Case

Locate and remove all screws from the rear and side panels. The Frigidaire FFMV1745TS typically has 8-12 screws. Remove all visible screws and keep them organized. Gently lift the panels away, being careful not to damage any wires.

Step 3: Locate the Magnetron

Now, find the magnetron. It’s a large, cylindrical component with cooling fins, usually located on the right side of the microwave. It features a large antenna (waveguide) that extends into the cooking cavity. You’ll see two large wire connections (filament wires), and it’s mounted with 4 screws.

Step 4: Test the Magnetron (Optional but Recommended)

Before you replace it, it’s a good idea to test the magnetron with your multimeter to confirm it’s the problem:

• Set the multimeter to resistance/ohms mode
• Test the filament terminals (you should see 0.1-3 ohms resistance)
• Test between the filament and case (this should show infinite resistance/open circuit)
• If the filament shows an open circuit or very high resistance, the magnetron is bad
• If resistance to the case is low, the magnetron has an internal short (definitely bad)

Step 5: Disconnect the Magnetron Wires

The magnetron has two large wire connections (filament wires) that connect to the high-voltage transformer. Typically, these are held with spade connectors. Use needle-nose pliers to gently pull the connectors off. Be sure to take detailed photos before disconnecting — these connections are critical and must be reconnected correctly.

Step 6: Remove the Waveguide Cover

The magnetron antenna extends through a waveguide into the cooking cavity. There’s a cover (usually mica or ceramic) over the waveguide opening inside the cavity. Carefully remove this cover — it may be held with screws or clips. Set it aside, as you’ll need to replace or clean it.

Step 7: Remove the Magnetron Mounting Screws

The magnetron is secured with 4 mounting screws. These may be in tight spaces, so use your Phillips screwdriver to remove all 4 screws. The magnetron is heavy, so support it as you remove the last screw.

Step 8: Remove the Old Magnetron

Carefully pull the magnetron away from the mounting bracket. The antenna extends through the waveguide, so you may need to wiggle it slightly. Be gentle — the waveguide and antenna are delicate. Once free, remove the magnetron completely.

Step 9: Clean the Waveguide

While the magnetron is out, inspect and clean the waveguide. Look for signs of arcing, burning, or damage. Clean any debris or food particles. If the waveguide is damaged, it may need repair, or you may require professional service for the microwave.

Step 10: Install the New Magnetron

Position the new Frigidaire 5304521745 magnetron in the same location as the old one. Ensure the antenna extends properly through the waveguide opening. The magnetron should sit flush against the mounting bracket. Secure it with the 4 mounting screws, being careful not to overtighten.

Step 11: Reconnect the Filament Wires

Refer back to your photos and reconnect the filament wires to the magnetron terminals. Push the spade connectors firmly onto the terminals, ensuring both connections are secure — loose connections can cause arcing and failure. Double-check that the connections match your photos exactly.

Step 12: Replace the Waveguide Cover

Install a new or cleaned waveguide cover over the opening in the cooking cavity. This cover prevents food splatters from entering the waveguide and causing arcing. Ensure it’s properly secured and sits flush.

Step 13: Reassemble the Microwave

Carefully replace all panels, making sure no wires are pinched or damaged. Reinstall all screws in their original locations. Tighten them securely, but don’t overtighten.

Step 14: Test the Installation

Finally, plug the microwave back into the wall outlet. Place a cup of water in the center of the turntable. Start a 1-minute cooking cycle on high power. Monitor for:

• Water should heat up (feel the cup after 1 minute)
• No unusual sounds or sparking
• No burning smells
• Microwave should run for the full cycle without shutting off

If the water doesn’t heat, or if you see sparking or smell burning, immediately unplug and recheck your work.

Troubleshooting

If the microwave still doesn’t heat after the replacement:

• Verify that all wire connections are secure (check with a multimeter)
• Test the high-voltage diode (it may also be faulty)
• Check the high-voltage capacitor (it may need replacement)
• Inspect the high-voltage transformer for damage
• Verify that the door switches are working (they prevent operation)
• Check for damage to the waveguide or antenna

When to Call a Professional

This is an ADVANCED repair. Consider professional help if:

• You feel uncomfortable working with high-voltage components
• You don’t have the proper safety equipment (discharge tool, insulated gloves)
• The waveguide shows signs of damage or burning
• Multiple components need replacement
• You’re not confident in your ability to safely discharge the capacitor

---

← Back to Top 20 Microwave Models & Common Repair Issues Guide

---

How Much Does This Repair Cost?

Repair route	Typical cost
Do it yourself	$80–$130 (parts)
Professional repair	$250–$400 (parts and labor)

Expect to pay between $80 and $130 for the OEM replacement magnetron (part 5304521745) if you’re following the DIY route. A professional repair shop will typically charge about $250 to $400 total when you factor in labor, which usually runs 1.5 to 2 hours for this model.

Recommended Products

KOKISO Home Microwave Oven Repair Kit – HV Capacitor 2100V 1.0uF, Diode CL01-12, Slow Blow Fuse 5x20mm, 6x30mm 20A, 6x40mm 0.75A 0.8A 5KV

When you’re replacing a magnetron in a Frigidaire microwave like the FFMV1745TS, having the right components on hand is essential for a complete repair. The KOKISO Home Microwave Oven Repair Kit includes multiple critical parts needed during the process. This kit features a high-voltage capacitor rated at 2100V, a replacement diode, and various fuses in different amperage ratings. This way, if other components need attention during the repair, you’ll have everything available without making additional trips to the supplier. Instead of purchasing individual components separately, this comprehensive kit saves both time and money while reducing compatibility risks.

The OEM Magnetron That Actually Fits the FFMV1745TS Without Rewiring

When you’ve confirmed the magnetron is dead — food stays cold, no hum, but the unit powers on — getting the right part matters more than saving $20 on a knockoff. This is the genuine component that will drop straight into your Frigidaire without adapter brackets or electrical surprises.

What works

• Connector and mounting tabs align perfectly with the FFMV1745TS cavity—no forcing, no shaving brackets, no second trip to the hardware store.
• OEM parts come with the correct thermal cutoff already tested, so you’re not inheriting someone else’s rework or partial failure.
• Voltage specs match exactly; you won’t trip the high-voltage capacitor or secondary transformer with an undersized unit that runs hotter than it should.

What doesn’t

• OEM parts cost more upfront—expect to pay $150–$200 versus $60–$80 for aftermarket, though the repair holds and you avoid callbacks.
• If you’ve misdiagnosed the problem (dead transformer or blown capacitor instead), swapping the magnetron alone won’t solve it—always test the high-voltage supply first.

I’ve seen people grab a cheaper magnetron only to find the connector sits loose or the mounting screws don’t line up, which wastes an hour troubleshooting a problem that wasn’t there. Order Frigidaire OEM part 5304521745 and you skip that headache entirely.

When you’ve confirmed the magnetron is dead — food stays cold, no hum, but the unit powers on — getting the right part matters more than saving $20 on a knockoff. This is the genuine component that will drop straight into your Frigidaire without adapter brackets or electrical surprises.

What works

• Connector and mounting tabs align perfectly with the FFMV1745TS cavity—no forcing, no shaving brackets, no second trip to the hardware store.
• OEM parts come with the correct thermal cutoff already tested, so you’re not inheriting someone else’s rework or partial failure.
• Voltage specs match exactly; you won’t trip the high-voltage capacitor or secondary transformer with an undersized unit that runs hotter than it should.

What doesn’t

• OEM parts cost more upfront—expect to pay $150–$200 versus $60–$80 for aftermarket, though the repair holds and you avoid callbacks.
• If you’ve misdiagnosed the problem (dead transformer or blown capacitor instead), swapping the magnetron alone won’t solve it—always test the high-voltage supply first.

I’ve seen people grab a cheaper magnetron only to find the connector sits loose or the mounting screws don’t line up, which wastes an hour troubleshooting a problem that wasn’t there. Order Frigidaire OEM part 5304521745 and you skip that headache entirely.