MotionRebuild shelfUnplug and unscrew

Solenoid

Also called actuator coil, door lock, chime plunger.

A coil and a sliding slug. Stroke is short, force drops fast with distance, and AC coils overheat on DC even when the voltage number matches.

If you are new to this category

These parts spin, push, or pump. A motor is a machine that turns electricity into turning. Some start turning as soon as you connect a battery. Others look identical and will not move until a small circuit tells them which coil to power next. The label, or the number of wires, is how you tell them apart.

Count the thick wires before you apply power. Two wires usually mean a brushed motor that can run from a battery. Three thick wires usually mean a brushless motor. Keep the board that came with a brushless motor.

A brushed motor

Two wires mean you can try a low, current-limited voltage and it should spin. The case often hides a label. If the only label you can find is on the machine, that voltage is the one to believe, not a hobby guess.

Mains voltage. Line voltage, and the DC bus just after the rectifier, both kill. A disconnected cord is not a discharged supply.

Specification. The right-hand column is what is typical. The label on the part in your hand wins if they disagree.
What to look for	Usual figure
Coil	Print the voltage. Washer door locks and chimes may be 120/230 VAC. Car locks are 12 V.
Duty	Many are intermittent. A hold-in resistor or a mechanical latch is how you keep one energized.
Stroke	Millimetres, not centimetres

Volts are electrical pressure, amps are how much current is flowing, and ohms are how hard the part resists that flow. A higher voltage than the part was built for is how salvage parts die on the bench. If a cell in the table says “read the stamp”, that stamp is the whole specification.

What people actually use it for

Latches
Ejectors
Doorbells
Cash-drawer kickers (usually 12 or 24 V)

Leave this one when

You needed a 50 mm travel. Use a motor and a lead screw.

Buying a new one is the better idea when

A catalog solenoid with a force-stroke curve, once the stroke is a design input.

How to tell if this one still works

Resistance first, then rated voltage briefly. Slug should snap. Coil should not cook in five seconds; if it does it was intermittent-duty or you used DC on an AC coil.

Tools you will want: Meter.

Where people actually find it

4 notes, most useful first. “Leave it” means the part is in that machine and you should not take it: it is dangerous, worn out, or only useful if you already know that exact repair.

Harvest at a glance
From	Call	How many	How often	Where it sits
Doorbell	Prize	2	usually	The chime.
Laser printer	Worth it	1–3	usually	Clutches in the paper path.
Blood-pressure monitor	Worth it	1	usually	The bleed valve.
Toaster and toaster oven	Bonus	1	sometimes	Electronic pop-ups.

Prize — take this firstDoorbell2 · usually
In this particular machine
Two coils and a plunger, low-voltage AC.
Where to look
The chime.
How to get it out
Take them with the springs.
The condition to expect
Good.
Worth pullingLaser printer1–3 · usually
In this particular machine
Small, DC, intermittent duty.
Where to look
Clutches in the paper path.
How to get it out
Leave the linkage if you want to understand the stroke.
The condition to expect
Good.
Worth pullingBlood-pressure monitor1 · usually
In this particular machine
A small valve that dumps pressure.
Where to look
The bleed valve.
How to get it out
With the pump.
The condition to expect
Good.
Bonus, if you are already in thereToaster and toaster oven1 · sometimes
In this particular machine
Holds the carriage down.
Where to look
Electronic pop-ups.
How to get it out
Short duty.
The condition to expect
Good.