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Please post experience of JVC HD750/350/550/950 bulb lifetime / lamp brightness drop - Page 3

post #61 of 738
Yes, I tried the lamp cleaning and had excellent results.

At first When I opened it up I was a bit disappointed to find that the socket didn't look that dirty at all. A bit "smoked over" looking (sort of like as shown in someones pictures in one of the articles above, but not quite as visible) but no real visible dust. I used a non-alcoholic environmentally safe glass cleaner on a microfiber lens cleaning cloth.

The cloth did not appear dirty or dusty after cleaning. Likewise the bulb was pretty clean too. But I wiped it down as well. A very small amount of residue there, I think mainly coming from the edges and not the glass itself. I let everything dry for a while before turning the pj back on.

When I fired the pj back up it looked noticeable brighter. When I walked in front of the lens I had to squint which I haven't noticed myself doing at all for a long time.

I then took out my meter and was stunned - it measured 89.1 lux, which was a whopping 75% increase!

For reference I have 635 hours on the lamp, using Normal lamp mode from mid throw with iris fully open.

Before cleaning:
lux: 50.9
lumens: 157
ftL: 6.35

After the cleaning:
lux: 89.1 (hadn't measured that since around the 300 hour mark)
lumens: 275
ftL: 10.75

One thing I noticed is that although my gamma did not change, my color temperature certainly did. I was measuring a dE of about 15 across the board after the cleaning. Although I didn't measure the grayscale right before the calibration, I had just calibrated it a few weeks ago and had a dE of 1-2 across the range.

Now it could have drifted some from my last calibration, but that was only a few weeks ago so I think its fairly safe to assume that this impacted the grayscale significantly. So just a heads up that for best results you may want to recalibrate afterward.

Also, previously my RGB gains for calibration at 100% was something like red 0, green -9, blue -25. After cleaning, my RGB gains were red -2, green 0, and blue -48. So in addition to the bulb brightness, I also picked up some additional brightness by raising green (this was on top of the post-lumens measure - IOW I had the 75% improvement before adjusting gains, so the gain adjustment gave me still a bit more of a boost).

If anyone else tries this please report back how it goes. If you have a light meter be sure to measure lumens before and after because it's hard to judge the increase in brightness otherwise (i.e. a 75% increase in brightness doesn't necessarily appear to be 75% brighter)... I allowed about an hour for the bulb to cool before removing it and cleaning.

This increase in brightness is a very welcome and surprising development. Nice! It will be interesting to read about the results of others who decide to try it.
post #62 of 738
I just cleaned mine, but didn't really see anything come off onto the cloth, I have only got an I1-LT probe so might not be that good for measuring brightness, but I'll compare it to a calibration I did two weeks ago for the 100 IRE reading.

What did concern me was that when viewing through the side of the lamp (where there is a grid/screendoor piece on each side) it looked like there is no glass and when blowing through it I could feel air come out of the opposite side. I'd have expected the arc bit to be within a vacuum.
post #63 of 738
Took the bulb out but didn't bother cleaning as I saw no visible dust/buildup. Maybe I'll try again when I go for bulb replacement in a few months.
post #64 of 738
"So when the manufacturers say half brightness, are they talking about measured or perceived?"

"the socket didn't look that dirty at all. A bit "smoked over" looking"

I wonder if it's condensed vapors from plastic parts.

Measured

I just cleaned mine, but didn't really see anything come off onto the cloth,

"it looked like there is no glass and when blowing through it I could feel air come out of the opposite side. I'd have expected the arc bit to be within a vacuum"

You can be sure that it is; the lamp must be hidden from view by the reflector.
post #65 of 738
Is this inordinate dimming a problem only with the original lamps that came out with the 'first run' of RS20's? My original lamp did seem to dim quickly, but my 2nd one has not. Is that typical?
post #66 of 738
Quote:
Originally Posted by millerwill View Post

Is this inordinate dimming a problem only with the original lamps that came out with the 'first run' of RS20's? My original lamp did seem to dim quickly, but my 2nd one has not. Is that typical?

For me I think it is a combination of a bulb which dimmed quicker than anticipated, along with this issue with some smoke-like affect that forms in the bulb socket.

I want to reiterate something I think is quite important. As I mentioned at the top of my post - there was really no dust or visible film that comes off on the microfiber cloth. The glass I am shining just looks shiner then when started. And I was disappointed when I didn't see all sorts of dirt on the cloth, thinking the experiment was for nothing.

The results were very concrete however. Multiple measures prior to the cleaning, versus multiple measures after the cleaning clearly showed a 75% increase - at least in my case. YMMV.

I'm not sure what it is. But this thin smoke-like affect on the glass seems to somehow act as a filter that can significantly affect the brightness. It was really surprising to see the results, particularly because the cleaning really didn't seem to remove all the much (besides make the glass look shinier than when I started).
post #67 of 738
One obviously has to unseat and remove the lamp assembly to do this, right?
post #68 of 738
Quote:
Originally Posted by millerwill View Post

One obviously has to unseat and remove the lamp assembly to do this, right?

Yes, I was slightly uneasy about that, having never done it. But it really is straight-forward. Basically the back panel is removed (two screws). Then that exposes the bulb assembly. There are two screens which are used to hold the bulb in place tight. Those simply are unscrewed then the bulb gets real loose. Then it just needs a little tug to have it unseat itself from the little pin/plug that connects the power to the bulb.

It was a little unsettling because I didn't want to tug too hard, but after some false starts I realized I needed a tad more on the pull, and it came right out. Going back in was a bit tricky because it wasn't very obvious when it was pushed in far enough. All in all I would say it was extremely easy - just a little unsettling the first time around because I couldn't help but feel everything was delicate (which it is).

Once the bulb is out it exposes the glass-like pane that the bulb essentially sits against. That's the pane that gets cleaned, and that's what you see in the picture that looks a bit "prism-ish".
post #69 of 738
Quote:
Originally Posted by lovingdvd View Post

Yes, I was slightly uneasy about that, having never done it. But it really is straight-forward. Basically the back panel is removed (two screws). Then that exposes the bulb assembly. There are two screens which are used to hold the bulb in place tight. Those simply are unscrewed then the bulb gets real loose. Then it just needs a little tug to have it unseat itself from the little pin/plug that connects the power to the bulb.

It was a little unsettling because I didn't want to tug too hard, but after some false starts I realized I needed a tad more on the pull, and it came right out. Going back in was a bit tricky because it wasn't very obvious when it was pushed in far enough. All in all I would say it was extremely easy - just a little unsettling the first time around because I couldn't help but feel everything was delicate (which it is).

Once the bulb is out it exposes the glass-like pane that the bulb essentially sits against. That's the pane that gets cleaned, and that's what you see in the picture that looks a bit "prism-ish".

OK, thanks. I have replaced my original lamp (that I still have, and should probably clean it too!), so have been through this process.
post #70 of 738
Just cleaned mine, did not see anything on the tissue, but color temp changed and I needed to drop blue and little bit of green. Brigthness appears to be better, not sure how much as I dont have light meter. My i1LT shows 20% increase, but it could be way off the real value either way as I dont have any method of keeping its directions constant.

All in all I am happy that I took the time to do this.

BTW, I used dry lens tissue, maybe I should try lens cloth with some moisture also.
post #71 of 738
Quote:
Originally Posted by karrih View Post

Just cleaned mine, did not see anything on the tissue, but color temp changed and I needed to drop blue and little bit of green. Brigthness appears to be better, not sure how much as I dont have light meter. My i1LT shows 20% increase, but it could be way off the real value either way as I dont have any method of keeping its directions constant.

All in all I am happy that I took the time to do this.

Hmm..interesting results. Making me think I should take the bulb out again and clean it anyway even though I didn't see any buildup. Are you guys cleaning both - the bulb and the pane?
post #72 of 738
Quote:
Originally Posted by christopher a View Post

Hmm..interesting results. Making me think I should take the bulb out again and clean it anyway even though I didn't see any buildup. Are you guys cleaning both - the bulb and the pane?

I cleaned both, although my hunch is the main benefit in my case came from cleaning the glass prism.
post #73 of 738
I also followed the advice and the result was amazing. Now for instance when the Popcorn Hour starts the white letters saying "Loading" are much more brilliant and clearer, the image has more pop.

I took some lens cleaning fluid and paper used for photo lenses and cleaned both the lens and the pane. The lens had black smear on it.

:-)
post #74 of 738
This is all very interesting. It would make sense that using some kind of solvent would be more effective than simply wiping with something dry. Whatever this film consists of, it's probably been more or less baked onto these surfaces at high temperature. I'm assuming the glass elements in projector optical paths are coated to reduce optical aberrations, internal reflections, etc. Perhaps some constituent of those coatings is being "outgassed" and deposited on other surfaces, or as noah katz suggested, perhaps it's heated plastic elements that are the culprit. Whatever the case, it seems counter-intuitive that something which appears largely transparent, and isn't obviously apparent on what you've cleaned it off with, would have such a profoundly negative effect on light output. Perhaps owners of other projectors with a fair number of hours on the bulb would discover something similar if they closely examined them.
post #75 of 738
I cleaned the panel behind the bulb in my RS20 which has 475 hours on it. When I looked at it by eye it didn't look very dirty. After wiping part of it with a microfiber cloth I could see there was a light film of dust on it. It wasn't that dirty so I wasn't expecting much of an improvement on light output. I was pleasantly surprised that it's noticeably brighter than before .
post #76 of 738
I have a new RS10 on the way. It should be here by the end of the week.

I am very excited to read that this film can be cleaned easily and restore brightness.

I will be sure to measure light output pre calibration and post calibration. I will then remeasure and recalibrate at set intervals.

When I have reached a certain number of hours I will clean the lamp and pane/prism and remeasure and recalibrate.

I am glad that people are seeing significant improvements.
post #77 of 738
Is it possible that it is not the cleaning that is having the effect...but instead the disconnecting / reseating of the bulb's power connector? I.e, if there was oxidation on the contacts that is scraped and removed by disconnecting...

Just curious if anybody has just removed the bulb as if to do the cleaning, but then just put the bulb back in...was there any change in brightness?

Bear with me...I don't even own a projector. But, I was getting ready to pull the trigger on my first (JVC RS-15) until reading this thread!
post #78 of 738
Quote:
Originally Posted by Steve Smith View Post

I cleaned the panel behind the bulb in my RS20 which has 475 hours on it. When I looked at it by eye it didn't look very dirty. After wiping part of it with a microfiber cloth I could see there was a light film of dust on it. It wasn't that dirty so I wasn't expecting much of an improvement on light output. I was pleasantly surprised that it's noticeably brighter than before .

Hi,

IMHO, it was the same thing on my HD1 (not very dirty) but (and I was very surprised, so I must check again my measure, it's too nice) it seems I have 14 fL and before (a few months ago) it was only at 10 fL and I didn't change the setting.
My lamp have more than 1 000 hours, if it's real (i'll check again at the end on this week) it's a very good news.
post #79 of 738
Quote:
Originally Posted by Craig Peer View Post

I have never used a projector yet that I didn't have to change out the bulb well before it's stated life ( or anywhere even close ). Loss of brightness, or using " too big a screen "

Craig I am happy to say my experience has been different than yours.

I have 5000+ hours on my InFocus 7210 and am on the second bulb. I replaced the first one at 2000 hours just because the notice came on screen telling me to do so. The bulb was still going strong, but I followed instructions and I put the used but functional bulb in a box and plugged in a new one.

After reading about other 7210 owners resetting the timer and letting the bulb continue I decided to try it. I am using a 135" diag. 16x9 screen and still using low lamp mode. I still have another new bulb and I am positive that if I put it in I would see a definite jump in brightness, but the InFocus is still quite bright on my screen even after all this time.

The only service my machine gets is that when it is turned on it stays on for 5+ hours and when it is turned off, it stays off for 12+ hours.
post #80 of 738
"Is this inordinate dimming a problem only with the original lamps that came out with the 'first run' of RS20's? My original lamp did seem to dim quickly, but my 2nd one has not. Is that typical?"

That corroborates w/my outgassing theory.

Whether it's plastic housing parts, insulation, or whatever, outgassing will decrease greatlyafter the initial bakeout.

"Is it possible that it is not the cleaning that is having the effect...but instead the disconnecting / reseating of the bulb's power connector? I.e, if there was oxidation on the contacts that is scraped and removed by disconnecting..."

Very unlikely IMO.
post #81 of 738
Interesting - of the poeple who have dirty prisms is smoking a contributing factor?
post #82 of 738
No smoking or barbecues in my room, but then, I perhaps didn't as get as much brightness increase as some seem to get.
post #83 of 738
So I went back in a cleaned the prizm and yes, there is a film there (you really can only spot it by shining a flashlight at the right direction). I hope someone else with some technical expertise would chime in here. I'm assuming this film isn't something that supposed to be there or perform a filter of some sort? Couldn't demo too much after completed but as someone else stated, color temp has changed, in my case + blue but I'll have to get some some measurements to be sure.

Chris
post #84 of 738
Quote:
Originally Posted by Tom_L View Post


Bear with me...I don't even own a projector. But, I was getting ready to pull the trigger on my first (JVC RS-15) until reading this thread!

One thing I have realized through the years at AVS forum is while I will get fantastic (the best?) advice possible here and I can research everything to death I need to decide how does the information really fit with my usage and viewing.

As in -- motion is horrible may mean that it is actually bad and it might also mean that it is not the best out there. The JVC's are great projectors and bright enough for most people. Those that measure them will notice drops in the brightness (that may or may not be fixable based on the last few posts), but I am just saying -- make sure that the loss in brightness is something that you would 1) notice and 2) actually miss.

If it was such a HUGE issue then people across this forum wouldn't love their JVC projectors.......

Not saying it won't be seen by you or be very negative based on your setup (I don't know) just saying make sure it actually is the right reason not to get the projector you had decided on.
post #85 of 738
Quote:
Originally Posted by mhdiab View Post

One thing I have realized through the years at AVS forum is while I will get fantastic (the best?) advice possible here and I can research everything to death I need to decide how does the information really fit with my usage and viewing.

As in -- motion is horrible may mean that it is actually bad and it might also mean that it is not the best out there. The JVC's are great projectors and bright enough for most people. Those that measure them will notice drops in the brightness (that may or may not be fixable based on the last few posts), but I am just saying -- make sure that the loss in brightness is something that you would 1) notice and 2) actually miss.

If it was such a HUGE issue then people across this forum wouldn't love their JVC projectors.......

Not saying it won't be seen by you or be very negative based on your setup (I don't know) just saying make sure it actually is the right reason not to get the projector you had decided on.

Pull the trigger and give Jason a call. Get the projector and enjoy. You can sit on the fence forever or you can enjoy watching movies. We enjoyed an AE900 for 2600 hours on a 12 foot wide HP screen (from AVS) and recently upgraded to an RS10 (again AVS). We expect many, many more hours enjoying movie nights.
post #86 of 738
Does anyone here that is following the bulb cleaning reports have experience with the RS1 and its bulb? I have a friend that has the RS1, and am wondering if he may be able to use the same cleaning technique to pick up extra brightness like can be done with the RS20. Thanks.
post #87 of 738
Hi,

I must check (I think I'll do it today) and I have an HD1 (it's the same as an RS1), and the cleaning is very very similar.

You must extract bulb (as for changing) and cleaning the part back the bulb (I use something for "dry" cleaning glasses).

With my first measure, I obtain 14 fL against 10 fL before, and I want check my measure because I'm very surprised.
post #88 of 738
Quote:
Originally Posted by Thebes View Post

Hi,

I must check (I think I'll do it today) and I have an HD1 (it's the same as an RS1), and the cleaning is very very similar.

You must extract bulb (as for changing) and cleaning the part back the bulb (I use something for "dry" cleaning glasses).

With my first measure, I obtain 14 fL against 10 fL before, and I want check my measure because I'm very surprised.

Glad to hear it. This doesn't surprise me. My brightness went up 70% based on ftL and 75% based on lux. I think its more telling to measure the increased brightness and report on it based on lux rather than ffL. That way the affect of your screen is not factored into your change in brightness.

What were your measures in fc or lux? I assume because you reported in ftL that this was measured by calibration software off the screen rather than a light meter, in which case the results are still very real, assuming accurate measurements.

I'm a bit surprised there is not more chatter and hype about this. IMO it is very significant. 75% brightness from a simple 5 minute cleaning? Sign me up! Of course everyone's amount of increase will vary based on a number of factors. I have heard of some folks seeing no increase, others seeing 20% and some others receiving upward of 70%. Nice.
post #89 of 738
Quote:
Originally Posted by lovingdvd View Post

I'm a bit surprised there is not more chatter and hype about this. IMO it is very significant.

Same here, I think this is the best thing I have done since I corrected gamma.
post #90 of 738
Quote:
Originally Posted by karrih View Post

Same here, I think this is the best thing I have done since I corrected gamma.

Funny you should mention that. Ironically, I think recalibrating the gamma frequently, which seems to drift considerably (cause TBD), is hugely underrated and overlooked. Most folks still do not seem to be aware of the great improvements in dimensionality that await them once their gamma is optimized.
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