[childe]

I have recently bought a JVC HD1 and foolishly connected it to my Xbox 360 which means my kids are getting more use out of it than me!

Given the price of the bulbs I want to maximise its life so I have issued strict instructions that when not in use the PJ should be turned off. However, is there a trade off between the savings from turning it off vs the wear and tear (to bulb and PJ) arising from constant on/off recycling?

In other words, what is the shortest period below which it would be more "harmful" to turn off than to leave on? Is it 15 minutes, 30 minutes, an hour or longer? Or am I wrong about the wear and tear and should turn it off at every opportunity even if only for a few minutes?

Thanks

[adam4478]

i don't know on the HD1 but it's widely understood that "hot starts" on pj's do your bulb life no favours at all and have been known to blow bulbs. I'd suggest that it's wise to leave for an hour to cool down once turned off - i always leave mine to cool for a few hours in between use if not don't turn it off at all

[Chris Frost]

I would concur. Striking the lamp hot or cold is where most of the wear occurs.

[T0M]

If I have finished using my PJ (also HD1) but intend to go back to it later I leave it on even if it means the PJ is running for a couple of hours.

I would reccomend you also use the 'hide' option on the PJ so you don't run the risk of screen memory (like screen burn but not permament) rearing it's head.

[Tribeless]

Adam, what do you mean by a 'hot start'.

I simply turn on my TW1000, then slip a DVD in. Am I not supposed to do this?

[AV Nik]

High Pressure discharge lamps require time to cool down completely before re-strike. On average, 1 hour is recommended between lamp off to lamp on.
Each time you start your projector, a ballast ignitor (capacitor type thingy) is what strikes your lamp. It's recommended using less strikes per day to save the life of the ballast ignitor more than the lamp.
Each time you strike a high pressure lamp, you loose lifespan so it's also recommended to keep the lamp on if your 'away' for up to 90 minutes. Any longer is arguable and cannot be determined exactly as there are several types of discharge lamps within projectors (UHP/VIP/Etc) and each has it's own detrimental effects.
If your 'away' for two hours, me personally would leave the lamp on as the cost of replacing the balast ignitor is a lot more than a new lamp. If your away for 3 hours, I would turn it off.
This is all my own opinion but with many years experience as a Lampy (lighting engineer).
Hope this helps.

[sapper]

Originally Posted by AV Nik

High Pressure discharge lamps require time to cool down completely before re-strike. On average, 1 hour is recommended between lamp off to lamp on.
Each time you start your projector, a ballast ignitor (capacitor type thingy) is what strikes your lamp. It's recommended using less strikes per day to save the life of the ballast ignitor more than the lamp.
Each time you strike a high pressure lamp, you loose lifespan so it's also recommended to keep the lamp on if your 'away' for up to 90 minutes. Any longer is arguable and cannot be determined exactly as there are several types of discharge lamps within projectors (UHP/VIP/Etc) and each has it's own detrimental effects.
If your 'away' for two hours, me personally would leave the lamp on as the cost of replacing the balast ignitor is a lot more than a new lamp. If your away for 3 hours, I would turn it off.
This is all my own opinion but with many years experience as a Lampy (lighting engineer).
Hope this helps.

Very interesting...

So in a training establishemnt, such as a school, it is better during the working day to leave the projectors switched on during longer breaks e.g. lunch time?

Currently, I tend to switch the bulb off but leave the projector on for the cooling fans to cool the system down.

There is debate within the staff whether we ar prolonging the life bulbs by switching them off when not in use, even during shorter spells.

Adrian
Adrian

[Tribeless]

Cheers AV Nik.

It's never too late to learn. Although I usually watch the single movie only, of a night, so given this, 'hot starting' has not been a problem for me.

[childe]

Thanks very much to all, this is very helpful. The conclusion seems to be to leave the PJ turned on unless I expect the interval of non-use to exceed 2 hours. Given my kid's usage patterns and my movie watching, this will mean it being on for around about 5 hours each week day and 25 hours each weekend. That's 50 hours per week, which could translate to a bulb per year using the lower estimates. Bummer! Time to get out the old 28" CRT for them to use again?

Thanks again

[Alpha_ET1]

Originally Posted by childe

Thanks very much to all, this is very helpful. The conclusion seems to be to leave the PJ turned on unless I expect the interval of non-use to exceed 2 hours. Given my kid's usage patterns and my movie watching, this will mean it being on for around about 5 hours each week day and 25 hours each weekend. That's 50 hours per week, which could translate to a bulb per year using the lower estimates. Bummer! Time to get out the old 28" CRT for them to use again?

Thanks again

I honestly think a lot of this is just the luck of the draw. My current bulb is sitting at 3002 hours which is just past its quoted lifespan. Previous one lasted about 550. First bulb was treated with respect, current one has been abused constantly(lead pulled out from wall and then switched on immediately loads of times). My usage seems similar to yours with kids 'controlling' the projector. Just forget about lamp life and enjoy the picture.

[AV Nik]

If you do decide to leave your projectors on, ensure there's either no image at all (blank screen/shutter on) or you leave a moving image on. Some older LCD projectors have suffered with the 'Bleach Effect' which is where part of a still image is still on the screen whenever you use it. Also known as a Ghost Bleach.
Typically, bleaching occurs after many hours of still/static image use. It would take at least 5-10 hours to have any affect at all but more than likely 100+ hours.
Hope this helps.

[childe]

Originally Posted by Alpha_ET1

I honestly think a lot of this is just the luck of the draw. My current bulb is sitting at 3002 hours which is just past its quoted lifespan. Previous one lasted about 550. First bulb was treated with respect, current one has been abused constantly(lead pulled out from wall and then switched on immediately loads of times). My usage seems similar to yours with kids 'controlling' the projector. Just forget about lamp life and enjoy the picture.

That is a very interesting observation and good advice. However, can I ask, was the first bulb your very first bulb, ie the one which came with the projector? If so is it possible it was not actually new when you got it?

[Alpha_ET1]

Originally Posted by childe

That is a very interesting observation and good advice. However, can I ask, was the first bulb your very first bulb, ie the one which came with the projector? If so is it possible it was not actually new when you got it?

Yes, the first bulb came with the projector which was bought new. It was replaced (by my current bulb) under warranty even though it was just outside the warranty period.

[childe]

I think for peace of mind, if I am going to let the kids continue to use the PJ, I am just going to have to forget how much it cost and use it like a TV. That is, turn it off when I think I have finished using it, without worrying too much about whether it might need to be turned on again in 30 minutes. Part of me now regrets not buying a cheaper PJ instead of the HD1, as I suspect I would very quickly have got used to any relative deficiencies it might have had. I would then be less worried about wear and tear. Anyway...

Also, I think I had better invest in a back up bulb - quickly!