Sound, light, heatRebuild shelfUnplug and unscrew
PTC heater
Also called ceramic heater, PTC element.
A ceramic element whose resistance rises with temperature, so it limits its own power. Found in some space heaters, car mirror defoggers, and glue guns. Safer than bare nichrome, and still not safe to bury in a couch.
If you are new to this category
Speakers, lamps, heaters, and displays. To test a speaker, touch a 1.5 V cell to the terminals for a moment. The cone should click once. A heater can start a fire if you remove the part that was supposed to shut it off.
Heat and bright light usually mean household voltage. Unplug first. If the original safety part is open, find out why before you replace it.
Touch a 1.5 volt cell to the two terminals for a moment only. A good cone clicks and moves. A scrape means the coil is rubbing, which will sound bad even if it still makes noise. The ohms printed on the magnet, often 4, 6, or 8, tell you what amplifier it expects.
Mains voltage. Line voltage, and the DC bus just after the rectifier, both kill. A disconnected cord is not a discharged supply.
Heaters without their cutout. Nichrome and tubular elements are happy to start a fire if the thermal fuse or tip-over switch is left out of the new circuit.
| What to look for | Usual figure |
|---|---|
| Behavior | High current when cold, falling as it heats. A cold resistance measurement looks like a short and is not the running power. |
| Fan | Many are designed to be cooled by a specific airflow. No airflow means the PTC still limits, but the housing may not. |
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
- A small heater that should not run away
- Dehumidifying a cabinet, carefully
Leave this one when
The ceramic is cracked. A crack concentrates current.
Buying a new one is the better idea when
A PTC with a known surface temperature, for anything left unattended.
How to tell if this one still works
Rated voltage, on a non-flammable surface, with the original airflow if it had a fan. Current should start high and fall.
Tools you will want: Meter, A non-flammable bench.
Where people actually find it
1 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.
| From | Call | How many | How often | Where it sits |
|---|---|---|---|---|
| Space heater | Prize | 1 | sometimes | Ceramic models. |
- In this particular machine
- Self-limiting. Still wants its airflow.
- Where to look
- Ceramic models.
- How to get it out
- Keep the fan with it.
- The condition to expect
- Cracked ceramic is scrap.