warm up LCD lamps before turning tv off?

Discussion in 'Displays' started by mylan, Mar 29, 2006.

  1. mylan

    mylan Screenwriter

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    I have always heard it is better to let the lamps in a LCD/DLP display warm up fully for about twenty minutes before you turn the tv off. This is supposed to help prolong lamp life and most of the time this is not an issue but there have been times when I have wanted to turn my LCD R.P. on just to check to see if the DVR was set up to record. I did this last night to record "The Unit" and afterwards left the tv on for about an hour (I forgot it) while we watched "American Idol" upstairs.
    What are some opinions? Did I shorten my lamp life more by running it for an hour or did I keep it from an early death by not powering on/off so much?
     
  2. Leo Kerr

    Leo Kerr Screenwriter

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    My theory on lamps - and it is only my theory with nothing real to back it up - is that there are two "ages" for a projection lamp:

    1. the raw number of hours it has been on, and
    2. the number of starts, or how many times the lamp has actually been turned on, which is one of the worst things you can do for the lamp.

    Manufacturers generally give an estimated lamp life - usually median - number of hours.

    I haven't tried to work out my internalized "intuition" about lamp aging, but it's akin to - a lamp start is an hour or so of lamp life, but perhaps not if the lamp is actually run for more than an hour or so.

    Actually, I suppose my theory has been more developed for, "okay, someone's at the door. Do I turn it off, or do I just let it run for the time being?" In that case, if I know it'll be less than half an hour, I'll leave the lamp on. If I know it'll be more than an hour, I'll turn it off. If it's in that 30-60 minute window, I don't know.

    Does this help? I'd be surprised...

    (The rational for counting lamp-starts comes from one of my first projector experiences. Nominal 2000 hour lamps, run for 9 hours per day. The first one failed explosively at 5000 hours. The second one (running in the sister-projector) was replaced at about 4500 hours due to low light output.)

    Leo
     
  3. mylan

    mylan Screenwriter

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    Yes, that does help. It is sort of like highway miles vs. city miles in a car. My take, like you, is that turning it on is the worst thing you can do (I like the hour-life analogy) but that the second worst thing you can do is power off before the lamp element, or filament, etc. gets to an fully on state and is then turned off. I do know the fan runs for a short time afterwards but I still think my leaving it on for a short time is better, or no worse, than a quick on/off cycle.
     
  4. Leo Kerr

    Leo Kerr Screenwriter

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    I don't suppose I really meant it quite that way. I don't think I meant that turning it off before it warmed up was a bad thing.

    Turning on a ballasted lamp (anything from a compact florescent or shop-florescent through a mercury or sodium parking lot lamp to a small projector lamp to a 5kW xenon arc lamp) puts a tremendous amount of stress on the ballast, electrodes, and, to some extent, the mechanical structure of the lamp.

    The details I'm about to give are for a xenon lamp; I suspect it holds true for conventional projectors, too. Starting lamps have a number of phases:

    Phase 1: Arc initiation. This starts by the ballast releasing a very high frequency, very high voltage, no-current, pulse. Generally for, oh, less than a tenth of a second. Then we go into...

    Phase 2: Boost. This is the phase that kills lamps and ballasts. On the xenon arc at work (1200w) it begins with a several hundred volt DC arc at a very high current. Over the course of about a second, it ramps both voltage and current down to the operating 12vDC at 100A. As the lamp ages, the boost phase takes longer and longer, and places even more stress on the system.

    Phase 3: Operation. As the lamp and its established arc continue to warm up, the color and brightness and arc stability improve as the remaining bits of "snot" vaporize to form the proper atmosphere in the envelope.

    Once you're past the boost phase, I don't think there's any real harm in shutting down early - with the following proviso: Most arc lamps do NOT like attempting to "hot restrike." This is a very bad thing to try.

    Leo
     
  5. Mary M S

    Mary M S Screenwriter

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    No structured poll to my thoughts on the subject; but when posters are discussing lamp life on various RP display units I have noticed a corelation.

    If they detail their viewing habits, those who cycle the display on/off more frequently appear to have shorter total hrs logged on lamps at failure. Those who leave display on for longer periods (or at least don't power on/off in under 30min-1hr increments) appear to be getting more hr's per life each lamp assembly. [IMO]

    Dying to see the hours on my orginal but my replacement is backordered. Our tendency here is to leave our RP display running for extreme lenghts of time even when we leave the room for long periods.
     
  6. mylan

    mylan Screenwriter

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    Thanks Leo, that is good information concerning the inner workings of a lamp. I had the same idea but in much simpler terms. I agree with the "hot restrike" theory fully.
    Mary, what do you consider extreme long periods? We may go take a break, go to the bathroom, etc. during a movie but come back within, say 20 minutes. I would not personally leave it on for hours unless I/we were watching something. Outside of lamp wear, there is also a great amount of electricity wasted.
     
  7. Mary M S

    Mary M S Screenwriter

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    Leo your info was much more informative than mine [​IMG]

    mylan ...I mean hours...I have menfolk.
    They have the infuriating habit of passing by the set and turning it ON. Only to watch for a sec (I'm guessing?) and continue on out the door to whatever project strikes their fancy. I find the display 'on' in a empty room, even after returning to the house after many errands, with no indication they have been back in the room during the majority of that time/ or they have left the house themselves!

    Other days I'm watching HGTV etc, I leave the room to change a load of landry or...and magicly .. no footsteps heard ...no one in sight...the display has tuned itself to the Speed channel. [​IMG]
    ...I don't recomend these kind of abuses [​IMG]
     
  8. mylan

    mylan Screenwriter

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    Mary, no your findings were in line with what I expected. I can agree that people that do not worry about it and treat a lamp based display like a CRT are going to pay down the road (literally!). It is a shame you cannot teach your menfolk, but old habits are hard to break, let your husband and boys spring for the back-ordered lamp. That might drive the point home. Yep, that is truly sad to let a beautiful display go unwatched!
     
  9. Mary M S

    Mary M S Screenwriter

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    Mylan,
    Finally accessed my Service M today.
    My original lamp showed 16,473 hours. I think that must be close to record for a GWII (Sony KF60XBR800).
     
  10. Gregg Loewen

    Gregg Loewen Video Standards Instructor, THX Ltd.
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    Mary,

    You need to change your bulb. The bulb currently has 30-50% less light output then when it was new.

    The rule of thumb is that at 70 percent of predicted life, the bulb has decreased in light output by 30%.

    Regards

    Gregg
     
  11. mylan

    mylan Screenwriter

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    Mary, that would seem to be a record alright! How did you access the service M? My set is the KDF60WF6055 and have had it since Nov. 04, I would imagine I have less than 1000 hrs. on mine.
    Gregg: assuming the lamp does not go out, after how many hrs. would you change it for optimum performance?
     
  12. Mary M S

    Mary M S Screenwriter

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    Sorry, forgot to check back this area for awhile! Just now saw these (not ignoring anyone [​IMG] )

    Gregg…thanks for the tip! …While I was posting last couple of wks - my lamp had died and I was waiting on backordered replacement. I had indeed noticed the dimming for a long while, just did not get round to ordering replacment when this was happening, but it was getting unwatchable particulary in dark scenes.
    I was waiting on new lamp to get the display back on line to see my total hours on the original lamp. Have it now and it is in, I will run my replacement lamp for 90 days (duration of warranty) and then order a second, install the second for its warranty period. - then reinstall the first. In future, this way I’ll have one on the shelf instead of sitting in dark next time I lose a lamp.
    Just did this for my mom also so that she would not be sitting waiting on backorder for 2 wks!
     
  13. Mary M S

    Mary M S Screenwriter

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    Sorry for the delay: here you go Mylan. All below apply to my model, but (reinvent the wheel?)I assume all recent years Sony RP have simalar/same SM layout.
    AT YOUR OWN RISK, entering or changing service menu.
    If any changes are made …BE SURE TO RECORD ORGINAL VALUES..and store in SAFE location. IE: staple to your owners manual?

    On my model KF60XBR800 to enter wait till your display has been off awhile (the only reason for this is so you will not be hot-starting your bulb which is detrimental to its lifespan)

    Start with display OFF additionally make sure on your
    SONY remote FUNTION button you have selected TV
    Hit in this order and within 1 second of each other:

    Display
    5
    Volume +
    Power (large green button, top right)

    The red light on the base of your display blinks to show 'status' - after a flash or two you'll hear a quiet "click", your TV should start shortly with the Green Service Menu codes overlaid on screen. (Its easier to tune to a blank input to read this.) If the red light continues to flash, hit the power button again to turn off the TV wait till lamp has cooled, and start over.

    Once in SM it is organized like so:

    Category……Item No…..Data…….Menu Mode
    Item Name……………………… Input Signal

    Service Menu Commands
    To Enter while in TV function with display off: Display – 5 – Vol+ - Power
    To save settings (changes): Mute – Enter

    To Navigate Service Menu:
    Up Item: 1
    Down Item: 4
    Up Category: 2
    Down Category: 5
    Increment Date: 3
    Decrement Data: 6
    Erase changes that have NOT been saved: unplug TV after cool down of bulb.
    To EXIT SM: Turn off TV wait till Lamp cool down and turn it back on. (or hit power button twice in a row while in SM, Once to turn unit off/once to turn back on. Very Quickly.

    To see lamp temp and life I just scroll using 1 & 4, I believe the Category you are looking for is
    Category” OPTION-E.
    This will display the temp the bulb is running at and the lamp hours.

    Hope this helps!

    (Credit to the wonderful "UMR does GWII tweaks" and all his hard work!!!}
     
  14. mylan

    mylan Screenwriter

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    Thanks Mary, i'll give it a go when I have a few HOURS, good grief, you typed a page full! Leave it to consumer electronics manufacturers to make something so seemingly simple so incredibly tedious. Anywho, thanks for the info.[​IMG]
     

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