The short version
A microwave that trips a breaker, smells hot or arcs inside is not a machine to diagnose at the workbench. The high-voltage section holds a capacitor that stays charged after the plug is out, and that single fact decides how far an owner goes on every symptom below. On a Farberware microwave the place to start is what is inside the cavity, because the door seal, the latch pawls and the turntable drive are the wear items on a housewares-brand cavity.
What the machine is doing
- Arcing or sparking inside the cavity — Metal, a damaged waveguide cover or burnt residue on the cavity wall.
- A hot or burning smell during use — Anything from burnt residue to a failing component, and the two are not distinguishable from outside.
- The oven runs but the lights dim in the room — The oven is drawing more than the circuit can comfortably supply, which is a circuit problem as much as an oven one.
- NEAR MISS: the oven is simply dead with no smell and no trip — That is a will-not-start fault, and its checks are simpler and safer than these.
The causes, ranked for this brand
- Metal, foil or a damaged waveguide cover causing arcing — Foil, a metal trim on a dish or a fork left in a bowl all arc. Ranked first on a Farberware microwave: this is compact housewares equipment used in small kitchens and dorm rooms, where how it is loaded and how often it is opened dominates everything a schematic would name.
- A shared or overloaded branch circuit — A microwave is one of the heaviest intermittent loads in a kitchen. Where it sits here: first, because it is the only cause here that an owner can both diagnose and resolve, and because it is genuinely common.
- A failing magnetron, diode, capacitor or transformer — The high-voltage section is what turns household power into cooking energy, and its components fail by drawing more current than they should. Where it sits here: common as a genuine cause and absolutely closed to owner work, which is why it sits below what can be checked safely.
- A damaged cord, plug or outlet — Over-range and built-in ovens sit in hot, tight spaces and their cords chafe. Where it sits here: ranks high because it is visible from outside the appliance, which is where all owner diagnosis on this page has to stop.
What to check first, and why that order
- Unplug the oven at the first sign of smell, smoke or arcing — There is no diagnostic step that comes before this one, and nothing on this page is urgent enough to skip it.
- Start at what is inside the cavity — It is the cause that ranks first on this kind of machine, so it is the check that ends the diagnosis most often and the one that costs least to make.
- Look at what else is on the same circuit — A kettle and a microwave on one kitchen circuit trip it reliably, and that is a wiring layout issue rather than an appliance fault.
The checks you can make yourself
- Move other loads off the circuit and test once — Plug the oven into a circuit of its own, or unplug everything else on the shared one, and run a short heat test with a cup of water.
About 15 min
- STOP HERE, permanently, at the cabinet screws — The high-voltage capacitor holds a dangerous charge after the oven is unplugged, and discharging it is a trained procedure.
Before you touch it
Safety
A microwave oven contains a high-voltage capacitor that stores a potentially lethal charge long after the oven is unplugged, and it does not need to be plugged in to injure someone who opens it. Do not remove the cabinet for any reason, at any age of oven, for any fault. Never defeat an interlock, never run the oven empty, never use it with a damaged door or cord, and never put anything metal inside it. If the oven smells of burning or shows smoke, unplug it at the wall and leave it unplugged.
Where the owner job ends
Call, or replace the oven, for every symptom on this page except a shared circuit and a dirty waveguide cover. An oven that trips a breaker, smells hot, hums loudly or arcs with an empty cavity is a high-voltage fault, and the honest advice on most countertop models is that the repair costs more than a new oven.
Related pages in this set
What is deliberately not here
This page covers Farberware microwaves as a class, not one family or model line. Deliberately not here: component ratings, fuse references and the high-voltage section diagrams, all of which differ by family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
