Turning off projectors at the power?

Energize · 6 May 2007 at 00:49

I've always heard teachers at school going on about how it has to be turned off properly because the fan needs to spin and it will damage it if it doesn't cool down etc.

Is this actually true? Because I can't see how turning it off at the power could damage it as no more energy is being put into the projector so it can't possibly get any hotter then it already is, it reminds me of that myth that turning off the pc at the power button instead of shutting it down can damage it.

daz · 6 May 2007 at 01:31

Some projectors use the fan to cool the bulb down more quickly. The bulbs are usually 100W+, and thus generate a lot of heat. They can stay quite hot for some time afterwards.

My projector doesn't need the fan to be on to cool down after being turned off though.

daven1986 · 6 May 2007 at 01:32

most if not all projectors' fans stay on for a bit after they are turned off, as if they are not running then yes it isn't getting hotter but it isn't cooling down enough either because when they are on the fans are running. so if the fans were to be turned off before the projector cooled down enough then it will probably damage it.
after it has cooled down it is fine to turn them off at the mains.

Jez · 6 May 2007 at 10:44

On all bulb based projectors that ive had the fan runs after the bulb shuts off, the fan cools the bulb in order to avoid overheating as the bulb is still very very hot even after it goes off. I know the exhausts on mine remain hot for a good 30 seconds or so after shutoff.

Corasik · 6 May 2007 at 11:37

I could be mistaken, but what if the gasses inside the bulb are hotter than the glass itself. (after all the glass is being constantly fanned to remain cool). So you turn the power off, fans go out, but the bulb gasses are still hot enough to raise the temperature of the glass.

Projector bulbs run VERY hot, and they are expensive. So why risk reducing a projectors bulb. Use the proper shutdown procedure.

cokecan · 8 May 2007 at 15:33

my old panny PT-LM1E actually spun the fans and cooled the bulb with the power cord taken out completly lol

it was apparantly one of its quick cooling features or something so you could turn the pj off, unplug it all, pack it up etc and it would still cool the bulb down to a safer temp to leave it to cool naturally (though not sure how well it would cool being packed away inside a carry case lol)

squiffy · 8 May 2007 at 15:41

Yes it is true, after bulb switches off you need airflow going through the optics until the temp goes down to a safe level.

RoachycaL · 8 May 2007 at 16:29

Ive got a teacher at school who switches his off at the wall. Its a Sanyo thing but usually the fans would run full speed until it cools down - I will need to inform him of this overheating procedure

Abyss · 8 May 2007 at 18:55

A projector is constantly cooled by its built in fan to stop the components and bulb getting too hot. Turn off the projector at the wall, and the fans will stop therefore the residual heat in the bulb will warm up the components inside. Usually the fans keep running to allow the remaining heat to escape when using the projectors power button.

Amoeba · 9 May 2007 at 16:00

Just to add! Why do you think that unplugging the PC without shutting down first damages it, is a myth? If you unplug a PC before it's had to chance to close all open files, flush the buffers etc you might very very likely lose data! Same with unplugging pen drives without doing safe removal..