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I switched projector on immediately after loss of power. Did I do the right thing?

Discussion in 'Projectors, Screens & Video Processors' started by Dillz, Jun 19, 2005.

  1. Dillz

    Dillz
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    Just got to the end of a film and my new BenQ PE5120 with just 8 hours on the clock powered off with a load of crackling noises coming from the power socket at the back of the PJ. Without thinking I wiggled the power socket and switched it back on, thinking that it would be less harmfull to the bulb to switch it on quickly so as to prevent the bulb from cooling. There was no abnormal shutdown lights displaying it just powered up as normal (strange!)

    It still works OK and seems none the worse for wear but after a correct shutdown and back in standby the power socket started crackling like crazy again. Seems I have a duff kettle lead! tried a spare one which has a much tighter fit and all is OK.

    Gave me a real fright I can tell you, I am worried silly now that it will have been damaged. Blooming typical ! I try and treat it with kid gloves and this happens. Kind of like new car syndrome! You'll get one scratch on the paintwork in the entire life of the vehicle and it is during the first week that you have it!

    I really hope it's OK, but I just wondered if I should have just let it cool down of it's own accord rather than switching it straight back on.
     
  2. Gary Lightfoot

    Gary Lightfoot
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    The projector is designed to be fan assisted on cool down so that if it should be restarted straight after, it won't be doing it on a hot lamp (which is bad for it). So doing what you did sounds like the best thing.

    Was the crackling caused by a loose power cable or was it internal do you think? If it's internal, I'd get it seen to and repaired asap.

    Gary.
     
  3. Ekko Star

    Ekko Star
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    From what you described sounds like you did a hot restart. Not the best thing for it but hey you live and learn. Hopefully it's not done too much damage.
     
  4. cyberheater

    cyberheater
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    Yep. Def a hot restart which isn't great for bulbs.

    Does anyone have any data on what effect a hot restart has on projector bulb life.

    I've seen lots of folks saying you shouldn't do it but never seen any actual data that supports the suppersition.
     
  5. Ekko Star

    Ekko Star
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    The following describes why temperature related failure occurs.

    Two factors that will always result in high lamp glass temperatures are the non-adherence to correct shut down procedures, and blocked or partially blocked air filters. It is essential that the projector is shut down properly after use in order to allow the cooling fans to reduce the lamp temperature sufficiently. The hottest part of a working lamp is the strike stem containing two electrodes. If the airflow over the lamp is in any way restricted, temperatures around the strike chamber will rise sufficiently to soften the glass. The usual consequence of this is that the pressurised strike chamber balloons outwards at its weakest point, producing a bulge or swelling in the stem. The stem itself is often pulled off its axis, effectively in moving the strike area away from the focal point of the reflector. This manifests as a reduced level of brightness to the displayed image. Elevated temperatures can also generate micro-cracks in the stem, allowing the ingress of air into what should be a vacuum. The micro-cracks grow rapidly, and after a very short time, the integrity of the structure is compromised and the stem shatters. Any mains voltage interruption or power cut, however momentary, will produce similar results to those outlined above.

    Taken from the FAQ link to my thread http://www.avforums.com/forums/showthread.php?t=171037
     
  6. dave_h34

    dave_h34
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    Hmmm, first power cut in 6 years last week and of course the projector was on when the power went off. A*^e, and indeed, f^$k.
     
  7. Gary Lightfoot

    Gary Lightfoot
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    If you power up a pj after a mains fail you have no control over the power-up cycle so you just have to let it do what it's doing. How would you know when to stop it before the lamp tries to strike or if the cooling fans on start-up have cooled the lamp enough so you can switch it off again? unless the pj knows it wasn't shut down properly it won't know any different than to start up normaly when you switch it on.

    Bit of a tricky situation really isn't it.

    Gary.
     
  8. Dillz

    Dillz
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    Thanks for the replies. So even a momentary loss of power means that any damage that was going to occur - has occurred. So I did a double no no by following an incorrect shut down with a hot start :eek:

    I haven't watched another film yet, so just have to hope it works OK, and that I haven't reduced the lamp life by too much.

    Incidentally we had a software demo at work last week and the girl doing the presentation brought along an Epson LCD. At the end of the presentation, you guessed it! the PJ was just unplugged at the socket and popped back into it's carry case. I wonder how long their bulbs last!
     
  9. cyberheater

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    Thanks Ekko_Star for the explaination.

    So it would seem that a it "might" be okay to pull the power from the plug providing there wasn't an instant build up of heat in the lamp housing to cause micro fractures etc... as long as you allow the bulb to completely cool.
     
  10. Ekko Star

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    No you don't have any control over the power up cycle. The PJ does not know if you've just switched it off 2 seconds ago or 2 weeks ago. It will just go through the normal power up cycle. Reasons why the power up cycle is like that is because you would have to wait for the fans to assume every power up was a hot start. Not everyone wants to wait for that cycle, it would become very tedious for many.

    No, no mights about it. If you pull the plug the fans don't get a chance to cool anything down. The bulb remains as hot when it was powered as it does when it is immediately switched off . Which is why the fans are on whilst it's working and also whilst it is switched off. If you pull the plug like that then the lamp actually gets hotter. A number of things happen with the latent heat if not dissapated adequately and quickly. The stem is the protrusion within the lamp that points to the lamp lens and has the two electrodes that create the strike that emits the light. When that stem softens it can bend which takes it off the centre axis, effectively this manifests in decreased light output over time, basically it is no longer at it's most efficient position. The micro-fractures can also occur due to the longer cooling down time. There is no control over whether the fracture is micro or fatal at that time, that is down to pot luck. However once there they obviously become a weak point. Unless a lamp has shattered, an expert can usually tell you why it has failed by studying the strike stem. 99% of the time it is down to heat, that is why they give you such a short warranty period on these things.

    I can assure you a PJ lamp is a minor miracle, simply put it's a very controlled minaturised sun.

    Essence of all this ? Enjoy it while it lasts, life is too short to miss out on the world of front projection. If you did that then it definately would be lights out.... :)
     
  11. cyberheater

    cyberheater
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    It's a pity that PJ manufacturers don't add a small back up battery just to power the bulb fan for a couple of minutes after total power failure to protect the bulb.
    I'm sure it would only add 10 quid to the PJ but could save you a small fortune.
     
  12. Ekko Star

    Ekko Star
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    Yes great idea ! Unfortunately replacement lamps also make them a small fortune :cool:
     
  13. explicitlyrics

    explicitlyrics
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    I believe that if a projector powers down due to a powercut, the best thing to do is get the air flowing again, if that involves turning it on then so be it. Yes turning the projector back on will cause the bulb to get hot again, but it is no different from regular operation so the fan should act normally (as though it had been on for an hour). There is no mistake in that logic in my opinion....

    Obviously that period between the power-off and power-on is damaging, but if it goes off, then surely turn it on ASAP!
     
  14. Ekko Star

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    No not a good idea at all. That is exactly the first thing manufacturers advise you to NOT do and is probably the single most damaging thing to do to your lamp! A hotstart is a very bad thing period.The PJ follows the normal power up cycle which assumes the lamp is sufficently cool, which is obviously not the case on a hotstart.

    The lamp is already extremely hot from before so the moment you start it again it takes the temp beyond it's threshold. This can cause the instances when the bulb actually shatters.

    The best thing you can do in intances like this is to use an external fan and cool the machine down as best as you can that way. This is not always practical but would be the next best course of action.
     
  15. explicitlyrics

    explicitlyrics
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    Fair enough,,, I hadnt really considered the bulb doing anything special when it turns on....
     
  16. monopole

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    According to an infocus engineer (this was posted on avsforum around a year ago), you should have left the projector off, allowing it to cool down naturally. He also said (in reference to DLP models) that pulling the plug on a DLP projector does not have any effect on bulb life - the "fast" cooling when you power down normally is there to get the bulb cool as quickly as possible in case the user wants to restart the projector. It's a warm restart that will kill your bulb.
     
  17. Gary Lightfoot

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    I remember that post too - Bob Williams in the X1 thread. The thing is it doesn't take into account the heat spike which has beed described by Ekko star in detail now, and as I've heard a similar account elewhere, I'm inclined to believe it.

    We have no control over mains failures or some other accidental power-offs, so there's not much we can do about it except take a chance on either leaving it off for an hour or doing a restart and hoping the cooling fans do a good enough job on start-up so that the lamp doesn't suffer if it's fired up again.

    Gary.
     
  18. dave_h34

    dave_h34
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    Thats what I thought, I raced upstairs to get the desk fan but when fumbling to remove the plug from the mains I realised my mistake, a mains fan isn't much use in a power cut!
     
  19. Nick_UK

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    Well, don't forget you can still get a UPS-1000D UPS from Ebuyer which will supply enough power to your pj to shut it down cleanly if the power goes off. For only £39.99 !
     
  20. monopole

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    You can find his post about lamp cooling here:

    http://archive.avsforum.com/avs-vb/showthread.php?postid=3025327#post3025327

    So, this could be InFocus only... I wonder if other manufacturers build in the same kind of tolerances?
     
  21. Gary Lightfoot

    Gary Lightfoot
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    I looked for that once before and couldn't find it. so well done. :)

    I wonder if teh archived stuff wasn't always available or I was just crap at using the search engine. :D

    Gary.
     
  22. Earney

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    On this very topic, I would also like to add and get your opinions please........
    I've had my first Projector for 2 months now (Toshiba MT200 , thanks to this site:smashin: ) and the lamp has a 3 month warranty. Yesterday I got flustered and turned it back on immediately:( after the power was cut, instead of giving it 10/15 mins (it took around 20 secs - after the first few seconds of trying, I got the standby and lamp lights showing red) ,when it eventually came back on everything seemed(?)OK but reading this thread it looks like I've definately done some damage. Just wondering how I should handle now - is there anyway the lamp can be checked before I possibly start to think about the warranty.
     
  23. Douzeper

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    great idea... on my way to buy one...
     
  24. Earney

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    Can any of you experts out there help a newbie please:confused:
     
  25. Gary Lightfoot

    Gary Lightfoot
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    I would think that any obvious damage would be visible in the projected image; does the picture look any different than before? If it doesn't, then it's possible that you may have just reduced the lamps life span by a few hours and nothing more. Without taking the lamp out and looking at it to see if the neck of the filament has waisted (become obviously thinnner), or if there are any other obvious signs of abnormality within, you won't really know. You may be perfectly fine as I've heard of similar things like this happening to other people (and myself once) and the pj has carried on with no apparent problems.

    You could try tech support for your pj and see what they have to say.

    Gary
     
  26. Earney

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    Thanks for the advice - much appreaciated:smashin:
     
  27. EldonTyrell

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    I have been doing some research into UPS's. I wonder how important it is to have the sinewave output, as this effectively seems to add about £100 to the price. I have seen several posts that claim if you don't have it, you could damage the PJ should the battery power ever kick in. Can anyone confirm / deny ?
     
  28. T0rNaDo

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    so how many ppl out there with PJ'S use ups's with them

    i took was thinking about using one just incase power cuts
    while using the PJ.

    wot size would be best to use........

    the PJ is a Z4 and the fan i think runs on for 1min after u shut it down
     
  29. EldonTyrell

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    You need to look at the watts (max) and ensure you get a UPS with enough power and preferably some to spare. 500va = 300 watts. I checked the Z5 and it uses 1.3A max. ampere (312 watts) so assuming only the PJ is to be protected I will go for something like a 650va UPS, which will give a comfortable margin. Each UPS will have a figure for the number of minutes it will last at max. load / half load, etc. There are quite a few at this rating at around £80 and some cheaper (like the Belkin ones). But to get the pure sinewave output, the cheapest I've found so far is £150.

    I am definitely getting one, a few months back we had one of those off ... on ... off ....on/off ... and then finally flickery back on type of power outages. Not risking it!
     
  30. T0rNaDo

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    cheers for info

    cant seem to find Z4 info from sanyo site..
    but i doult its more then the Z5 is..

    i might also run a pc case from it.
    but i do have some smart 700ups's here so i could use one just for pj.
    and another for pc case.

    be idea to check if the ups would keep the pj up
    and let it cool the bulb down by trying it out.
    but if it didnt then u risk a inproper shutdown ..

    hmmm
     

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