The short answer
A B machine that does nothing at all is usually unpowered, unlatched or locked rather than broken. A countertop machine shares a kitchen socket with everything else on the worktop.
What you observe on these models
- The display is lit but nothing happens on start — Supply is fine, so look at the door and the lock.
- Some panel buttons respond and others do nothing — A membrane fault rather than a board fault.
- It works sometimes and not others — That intermittency points at the supply or the door rather than at the control.
- The clock is flashing — The control has restarted and may be waiting for a prompt to be answered.
- NEAR MISS — it starts and then stops after a few seconds — That is a door or a thermal fault and it needs a different page.
Causes, most likely first on the B family
- The door not latching properly — First on this platform: no microwave will start with its door switches unmade, and a latch hook that has worn or a door that has dropped will hold the door closed without operating them. A door that needs a push to start the machine has already told you the answer.
- An internal fuse opened by a failed door switch — Second: when a door switch fails out of sequence it blows the line fuse on the spot, so the machine goes from working to completely dead in one closing of the door. That history points here precisely.
- A control lock, a timer that was set but never started, or a delay — Third: all three leave a machine that lights up and does nothing, and all three clear from the panel without tools.
- Control board or touch membrane — Fourth: a panel where some buttons work and others do nothing is a membrane fault; a panel that is dark with the socket proven is the board.
- A timer or clock waiting to be confirmed — Last: many machines will not accept a cook instruction while a clock or timer prompt is unanswered, and the panel gives very little sign of it.
Check in this order, and why that order
- Test the socket with something else — It is the commonest cause of a dead microwave and it takes ten seconds.
- Open and close the door firmly, then try again — A latch that has worn will hold the door without making the switches.
- Look for a lock symbol, a set timer or a delay on the panel — All three leave a machine that looks completely dead.
- Think about whether it died the instant a door was closed — That history points at an internal fuse opened by a failed switch.
- Stop at the case — A blown internal fuse on a microwave is a service job, because the capacitor behind it holds a charge after the machine is unplugged.
Before you open anything
Safety
Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. Treat that as the first step of every check below that involves a panel, a grille or a cover.
Models in the B family — The numbers this page covers.
Reference| Model number | Family key |
|---|---|
| B20PXP78 | avanti:microwave:b |
When to call a technician
Sockets, doors, locks and timers are yours. On these models the line falls at the outer case, and everything behind it. Call without working through anything at all for a socket or plug that heats under load, which is a fire risk rather than a nuisance.
Nearest pages of this class
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