How long to leave a microwave oven to allow capacitors to discharge before taking the back off

[NY]

The door-latching mechanism has failed on our microwave. It may be possible for me to repair it if a spring has become unlatched.

How long should I wait after unplugging a microwave before any capacitors have discharged and it is safe to take the back off to see how easy it will be to access the latching mechanism.

Sod's Law: not only will the door not stay closed, but the door-closed interlock is not sensing that the door is closed so it will not turn on :-(

New 46 cm width built-in microwaves are horrendously expensive, as far as I can see.

[Andy Burns]

Some models deliberately blow a fuse if the door latch is faulty.

[Harry Bloomfield Esq]

NY expressed precisely :

That depends on if the discharge resistor in parallel is doing what it should, in which case just a few minutes, otherwise several hours before it is safe.

[NY]

Problem solved. On further googling, I discovered that it was going to be the sliding latch on the door, rather than the catch mechanism in body of the microwave oven. The internal trim on the door is designed so it can be prised off. The spring on the sliding latch had come off the peg that secures it to the door - because the peg had broken off. Luckily there were two tabs 8 mm apart next to where this peg had broken off, so I cut a piece of wood to fit between them, screwed a little screw into the wood and hooked the spring over it. Job done. Normal service resumed. ;-)

So I didn't need to go inside the casing of the oven.

[GB]

Do all capacitors self-discharge in a few hours? Can you bet your life on it? :)

[Paul]

That's how Nicola Tesla got his start -- by picking himself off the ceiling.

Paul

[Animal]

Discharge resistors can fail. The PSU cap in a nuke can kill you effortlessly. If OP doesn't know how to discarge the cap or what to not touch, leave the job alone.

[Harry Bloomfield Esq]

GB formulated on Saturday :

In time, yes. All capacitors exibit some leakage.

[Brian Gaff]

Yes this always used to be the case. They use a bleed resistor to discharge them in all the ones I've seen. There may though, be an easier way to get at the latch.. Sometimes once you take off the top cover which is U shaped, you can get at some fasteners that allow the control panel to hinge out making the switch more get attable. Obviously this was some time ago for me, when most Microwaves had mechanical pingers though, so modern ones could be constructed differently. Think the ones I saw had the innards made by Sharp. Brian

[GB]

I'm seeing some suggestions that it could be rather a long time. :)

[Brian Gaff]

I guess today you may get the safety police after you but in them days of the wild west repair man, then the answer was most of the time!

A handy insulated bit of wire with insulated crock clips either end and a circuit was always a good thing to have. Mind you you could say the same about CRT tvs where the tube itself could be charged up. Brian

[John Walliker]

But not always in the direction you expect. I once fully discharged a high voltage photoflash capacitor (oil filled) and left it sealed in a storage box for a few months. Afterwards it had accumulated enough voltage to produce a substantial bang when I checked it with a screwdriver across the terminals.

See:

John

[The Natural Philosopher]

The electrolytic sort called 'batteries' stay charged for years. The ones inside solid state drives are guaranteed to stay charged for a year, minimum.