Tombob's post above got me thinking. As many do, I've got a dedicated 110v for my PJ. The way I understand it, if it's hot and the power goes out for any length of time the bulb stands a good chance of bitin' the dust. Many have run a wire from their PJ to a UPS in the A/V cabinet to prevent this. Just exactly how to do it, and stay within code, is still up for debate,
Okay, enough blabbering. How about a small, battery operated fan. You could hang it on the projector, blowing into the vent, in the event of a power failure. They're available from the Dollar store or WalM*** . Normally, you'd be watching a game, movie, show, whatever while the PJ is on, so you'd be right there to hang it and turn it on. Leave it on just long enough to cool the bulb down. An added plus is the substantial cost savings as oppossed to a UPS and the wiring.
Anyone hear of such a thing?

Battery opperated means someone has to check the battery. :) Get a 12v fan and thermostat and hook it to a battery if you must, or hook it to a 12v wall wart and have it switch on when needed.

12v quiet fans are readily available for PC's... and cheap'ish.

I have had a couple of major hardware projects messed up big time by fan failures. We found that some fans would run a thousand hours and then just die. If you want to be sure, you need to have two fans. That way, either one fails, your still going to run.

For the projector fan problem, I have read from other forums that they just turn AC off to their projector (typically sp4805) and they don't see any big problems with bulb lifetime. In fact, the 4805 has a problem where the fan that cools the bulb fails (like mine did). The projector has a fail safe switch just above the bulb. If it gets too hot, it kills power to the projector.

Therefore, I am not worrying about putting a thermal monitor in to make sure that the fan continues to run. (Bythe way, many fans have a tach sensor that will go closed when the fan stops running. You could use that type of a fan with a battery and a piezo buzzer to sound an alarm if you wanted to.

Both of the above posters didn't seem to get the point of the thread. The poster is asking about a backup fan system in case the power fails and the bulb is left to bake inside of the PJ.

The whole idea seems a bit elaborate to me though. I'd prefer to have a fresh supply of air to the PJ and assume (or hope) that it was designed to be switched off without a cool down cycle at least a few times. Honestly, if the bulb were toast there would be a lot of unhappy people who accidentally unplugged their PJ's.

As far as the SP4805 goes, it is designed not to have a cool down. when I was at school we did a project for HP, and as a comparison we had in our possession an X1. We took it apart (several times actually) but once installed a thermocouple to measure inside heat temps on shutdown. The temperature only rose 7 degrees before retreating again.

Indeed, we wondered if in some cases it might be better for the bulb to cool down more slowly without the aid of a fan.

In any case, it is MY opinion that it is a small risk to take. I would just ensure that the PJ was supplied nice fresh air (not stagnant hot air) so that it is already at the cooler side of its operational limits to begin with.

Tboy

Thank you for the replys guys. Tboy555, that's what my concern was. Being new to the projector world, and the issue being stressed in the Sharp manual, I didn't want to have to blow $300 for a new bulb when a simple $5 fan would have saved it. As my theater is dark (no windows), I'm able to run the PJ in the "econo-mode", so it's not running as hot. A fresh air supply is impractical, but worth figuring out. Power outages aren't common in my area, but I have a battery back-up for my sump pump too. :)

dnddwilson,

What I meant by fresh supply is that you've not mounted it in a stuffy whisper box or something without providing adequate air flow.

Just make sure the projector is running cool, you should be fine.
Tboy

Hanging out in the wind on a 12" downrod.... like when the police found me... but that's another story. :)