Filed
People expect a lightning story. A bang, a flash, a dead appliance. That is not what usually happens.
This county averages somewhere around sixty-eight thunderstorm days a year, and the appliances that die because of them mostly die quietly, weeks later, from an accumulation of events that nobody wrote down.
The mechanism
A storm cell knocks power out for a second and a half. It comes back. Then it does it again. Then the grid recovers and the voltage overshoots or sags while load rebalances.
Inside a cooking appliance, the user interface and the logic run off a switch-mode supply — a small circuit converting line voltage down to five or twelve volts. Every one of those events is a charge-and-collapse cycle on that supply’s input side. Electrolytic capacitors do not enjoy this, and they are sitting in a cabinet that is already warm.
Nothing fails on the day. It fails in October, when the capacitor has finally lost enough capacity that the rail sags under load and the processor resets mid-cycle.
What the failure looks like
- Display dark, appliance otherwise silent
- Display lit but ignoring touch, or registering phantom presses
- Relays chattering instead of latching cleanly
- Oven heating with no display, or a display with no heat
- Appliance resetting itself partway through a long bake
- A steam oven that powers up perfectly but never produces heat
That last one is worth separating out. It is frequently a thermal fuse rather than a board, and a fuse is a fraction of the cost.
Do not start at the board
The board is the expensive assumption. It is also the one most often replaced without cause, and a replacement that goes into a bad supply environment fails again the same season.
The order that actually works:
- Both legs at the appliance, under load. A 240-volt appliance running on one healthy leg and one weak one produces symptoms that look exactly like logic failure.
- The low-voltage rail. Measured, not assumed. A rail that sits low or ripples is the fault, and it usually sits upstream of the part everyone wants to replace.
- The relay board separately from the control board. These are different assemblies with different failure rates, and diagnosing them as one unit is how people end up buying both.
- Connections and ribbons. Heat cycling loosens things. A reseated ribbon has fixed more intermittent panels than any part order.
What actually helps
Surge protection at the panel is worth more than a strip behind the appliance, because a built-in is usually hard-wired and there is no strip to plug it into.
If the house has a standby generator, note when transfer events happen. A control that failed during or just after a transfer is telling you something about the supply, not about itself.
And if the power goes out mid-cycle repeatedly during a summer afternoon, it is reasonable to switch the appliance off at the breaker until the cell passes. That is not superstition — it removes the appliance from the event entirely.
The delay is the part people miss
It is worth saying plainly, because it does not match how people expect electronics to fail: the damage rarely shows up on the night. The multi-day outages this region lived through after Matthew in 2016, Irma in 2017 and Helene in 2024 were each followed by a run of control failures weeks later, in appliances that had been used normally in between.
So an oven that came through a storm week working is not thereby cleared, and a board that dies in a calm fortnight has not necessarily died of old age. When the failure is dated against the last outage rather than against the last time the oven was used, the pattern usually resolves itself.
What that means practically is that the supply gets measured before the board gets condemned. A control being fed badly will take its replacement with it, and finding that out after the second board is an expensive way to learn it.