Please post experience of JVC HD750/350/550/950 bulb lifetime / lamp brightness drop - Page 25

I just bought a used HD350 a few weeks ago and while I love the image, I have been a bit dissapointed in the brightness. Coming from a CRT projector I expected practically any digital to be brighter. After reading this thread I decided to take a look inside. I would clasify my prism type assembly as filthy and also had a small fragment that had flaked off from that plastic bezel that holds it. The lamp glass was very hazy as well. I went through about six cleaning wipes until I was satisfied with the results. Hooked up the projector and there was immediatly a difference in the way whites looked. I would not say that my overall image was drastically brighter but it certainly has more depth and clarity as well as the whites actually looking more white where they had been dingy yellow before. I will probably change the lamp once I get everything else up and running but I'm very happy with the cleaning results thus far.

How many hrs was on the lamp may I ask?

About 1070 hrs.

Hit the 2700 hour mark and notice a slight greenish bar on the left side.....hoping a bulb replacement fixes it. Could also be that I just moved the unit to an unfinished part of the basement where the foil,color insulation is on that side of the wall causing a reflection?.......I'll order the bulb today and keep you posted

Did you ever figure out the greenish bar on the right side of the screen/picture?

Does not sound like a bulb ....

Have had that along with the "magenta strip" on my HD-950. Second bad optical block

Two bad units since purchase in '09. Sending my second unit in for repair through my retailer that I bought extended warranty through. It is a tough place to be in because I am not interested in 3D much and from my research there are some who feel that there have not been real improvements to 2D since the Rs25 and 35, but I kind of dont want another one as they seem to be having so many problems. I would really hate to get another one and have it cave after my warranty expires and have to spend more than it is worth to fix.

Hello
Was there any general consensus in this thread as to whether or not the final generation of these lamps with the "flapper" performed better in terms of retaining their brightness over the earlier versions?


Thanks

Or whoops, am I in the wrong one of these type lamp threads?? Have forgotten with retail numbering system. Wanted the thread with the RS50, RS60, RS55, RS65 type lamps. Or if you don't mind and can let me know real quick.
Edited by RonF - 1/14/13 at 8:41am

I don't know about "flappers". Never heard of any significant changes in our lamps' designs. It seems like the biggest factors are: manufacturing variation, the brightness setting one uses, the frequency of strikes (on, off), ventilation -- in addition to hours. With my current bulb, I found by 1500 hours I had to switch from low to high power to retain the same level of calibrated brightness -- but that one move actually bought me more brightness than at low power when the lamp was new, so I had to stop down the iris a little.

I'm thinking now I posted in the equivalent RS25, RS35 projector lamp thread. Sorry will go look for the other one.

Hi,

I recently bought a second hand HD350 (I live in the UK) and I need some help regarding lamp brightness.

When I got it I was told that the lamp was the original one as it was already at 2100 hours I decided that I would buy a new one straight away.
I then purchased a replacement lamp made by a company called Diamond Lamp (http://www.diamondlamps.net/) from a reputable UK base retailer. Once installed I did notice that the picture was colder but not really brighter. After a white point calibration using HCFR and my i1 Display Pro I found out that the new bulb was giving the exact same brightness as the original JVC bulb with 2100 hours, ie roughly 20 ftL in both cases. they replaced the bulb but the second one gives the same results.

Here is a summary of my setup:
- Projector: JVC HD350 installed 2.36m from the screen (minimum zoom and fully open Iris to get maximum brightness)
- Screen: DIY Fixed frame with white ORAY PVC screen material (gain 1 assumed as I can't find the datasheet) 1.75 m x 0.98 m = 5.74 feet x 3.21 feet

Here is a summary of my measurements with the new bulb:
- 20.86 ftL at 6587 K
Could someone tell me what it is equivalent to in term of Lumens? I think it gives 386.80 Lumens but I am unsure

The Projector central calculator tells me that I should be getting 54 ftL for this setup based on the manufacturers 1000 Lumens figure. I do not believe that the HD350 gives that much at 6500K but I should be getting more than 386 with a brand new bulb no? If I start at 386 with a new bulb then what will I get after 500 hours?

Before anyone asks I have cleaned the prism and I was surprised to see that it was actually much cleaner than what people have reported.

Your help would be really appreciated.

Cheers

Damien

Hard to predict. Even with a real JVC lamp, it's all guestimates, though the official lamp life spec is in theory the number of hours it takes to get to half light output.

380 lumens in your setup = 20.8 fL is correct (or close enough). Are you buying the lamps from a generic supplier or a trusted source?

These numbers do not make much sense as far as how bright it should be. What type of device are you using to measure this?
Remember calibration devices do not provide accurate fL or accurate lumen measurements in general, you need a light meter instead (you can get them under $30 on Amazon).

That is a really small screen if you gave us correct measurements, I'll round up and call it 80".

With the IRIS clamped down, I would eastimate you would get 15 fL to 20+ fL MINIMUM.
With the IRIS open, even in low lamp you should be getting 25 fL to 30 fL.
In Lamp High, you should be getting well over 35 fL to 40 fL.

And I am estimating on the low side of those numbers above, it should generally be 10% to 20% higher than that even.

There could be some variances due to external factors, but I wouldn't expect you'd get much dimmer on a new lamp, that'd be unusual at best. You could get a high as 45-50 fL in some modes, but only the brightest uncalibrated mode. PJC often uses dynamic modes or near-brightest modes for their lumens baseline, so you cannot trust any data from that.

Hi Guys, Thanks for the help.

I am measuring the ftL with a Xrite i1 Display pro and the HCFR software. The Lamp is from a trusted source (popular source of lamps on the UK AVFORUMS).

I have at home a Sekonic 308 light-meter so I will try to get an EV reading tonight. Do you know how to do the measurement and then Lumen calculation from an EV measurement from a Lightmeter? Do I take the measure at the screen surface. The Sekonic can do direct and reflected measurements so I'll try both.

As I said the original lamp that was in the projector is supposed to have been used for 2100 hours and was measure with the i1 Display pro at 19.8 ftL @ 6500K. I guess this is fair as the bulb is really old and must have lost about half the original brightness. But I was really surprised to see that a brand new bulb was only 1ftL brighter at 20.8 ftL @6500K.

My RGB gains/offset that give 6500K are as follows:-

New Diamond Lamp 6500K, 0 hours
Gain: R=0 G=-84 B=-115
Offset: R=-3 G=0 B=-1

Old JVC Lamp 6500K, 2100 hours
Gain: R=0 G=-77 B=-98
Offset: R=-3 G=0 B=-1


Do these values seem normal to you guys?

By the way, yes it is a small screen. I am planning on getting a bigger one so I am worried about low brightness I can see that you have a nice calculator, I will have a go later today.


Thanks again

Damien

You stand at the screen with your back towards the screen, and point the light meter towards the projector's lens. You should take at least 3 measurements, though the standard would be to take more. I just take 3 like a slash (\) over the screen, from top left corner, middle, and bottom right. Angle your the meter back and forth towards the lens until you see the highest reading at each of the three points, take that number. Add the 3 numbers together and then divide them by 3. That gives us a quick average 3-point reading.

There is an excel spreadsheet here to help convert LUX to Lumens:
http://www.avsforum.com/t/1315110/jvc-rs40-lumens/180#post_20392415

Edited:
I should probably add a lux to lumens convertor in my calculator, will do in another version.
Edited by coderguy - 5/14/13 at 11:39am

Thanks for that,

Do you think that the Sekonic is suitable for light measurement as an EV meter. It is then easy to calculate the Lux value ( E=2.5*2^EV )

Damien

I would assume it would work, but don't know that much about those kind of light meters.

Just done some measurements

Measures made at custom RGB settings Gain: R=0 G=-77 B=-111 Offset: R=0 G=0 B=0 and Gamma curve "Normal" (These settings give me a measure temperature of 6500K), Lamp Normal

1st method sekonic direct:
Measured: 6.2 EV
Equivalent Lux: 2.5*2^6.2 = 184 Lux
Which gives for my setup 308 Lumens

2nd method i1 Display Pro reflected
Measured: 20.9 ftL
Which gives for my setup 387 Lumens


Measures made at default JVC 6500K setting measured at 7790K, Gamma set to "Normal", Lamp Normal

1st method sekonic direct:
Measured: 6.4 EV
Equivalent Lux: 2.5*2^6.4 = 211 Lux
Which gives for my setup 354 Lumens

2nd method i1 Display Pro reflected
Measured: 24.6 ftL
Which gives for my setup 456 Lumens


Measures made at default JVC "High Bright" setting measured at 10400K, Gamma set to "Normal", Lamp Normal

1st method sekonic direct:
Measured: 6.8 EV
Equivalent Lux: 2.5*2^6.8 = 279 Lux
Which gives for my setup 468 Lumens

2nd method i1 Display Pro reflected
Measured: 31.7 ftL
Which gives for my setup 588 Lumens


Measures made at default JVC "High Bright" setting measured at 9800K, Gamma set to "Normal", Lamp High Power

1st method sekonic direct:
Measured: 7.2 EV
Equivalent Lux: 2.5*2^7.2 = 368 Lux
Which gives for my setup 616 Lumens

2nd method i1 Display Pro reflected
Measured: 44 ftL
Which gives for my setup 816 Lumens


As you can see I get close to the 1000 Lumens advertised but this is at High power lamp, reflected and High Brightness mode. I also suspect my screen to have a gain higher than 1 but this is something I can not check for sure.

Maybe I should get a Lux meter in order to get a proper assessment of the projector Lamp.
Edited by damien55 - 5/14/13 at 4:08pm