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G70 & G90 Tube killer?

1638 Views 36 Replies 14 Participants Last post by  LaserMark4
I have been watching the G70 & G90’s for sale and wonder about the tube life.

In general CRT manufactures state the tubes last for 10,000 hours and in most cases this seems about right for what I am seeing. By looking at the many projectors that I have purchased and checking tube condition against the hours and even the replacement date (so nice many of the machines had it written inside with marker.) I do concur that 10,000 hours is easily achievable when used properly. I have also watched many PJ’s for sale with pictures of their tubes and hours used, some of the machines are on the first tube set, others the second or third, again the 10,000 hours seems about right if not more.

So here is my point when I see G70’s and 90’s for sale many of the tubes are shot long before the 10k mark usually its about 5,000 to 7,000 hours. Half of the PJ’s are sold with the old burnt tubes and the other half have been replaced, what is going on here?

I try to keep in mind the Sony machines are recently taken out of a corporate world where people do not use the machine properly, IE static burn or too high B/C thus could be causing low tube life. Lately I have been seeing more large Sony’s PJ’s removed from home theaters and again the story of the tube life does not add up to 10K.

My position is the G70’s and G90’s have a tube life of about 5-8,000 hours depending on how picky you are about white balance. To me these tubes show the wear more quickly than others and the hours add up faster.

So would others agree with me on this one? Anyone have personal experience with either projector and the tube life?

Personally I would enjoy a G90 but the 1209 or 9500 seems like a better deal in the long run should you just have to have a 9†machine… what do you think?

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The G90 are rated 350 ansi lumen, other projectors like the Barco 909 are rated just over 200 ansi lumen - they are using very similar crts. Yes, the G90 kills the tubes very fast. I have seen many 909's that have come out from corporate use with none or very little wear on the crts. Every G90 seems to have heavy wear, even those used in HT, and at a very low hour count.

You can probaly get longlife from a G90, but you have to turn down the contrast. At the factory preset, they will be shoot instantly.
I would have to agree. A default contrast setting of 80 from the factory seems crazy to me. I have just acquired a G90 with just over 600hrs and it shows a significant amount of burn, probably between 7/10 and 8/10 on the CRT wear scale. My BG808s with 3000hrs shows no wear whatsoever on any of the tubes.

Since I'm so picky about the image quality (isn't this why we put up with these monsters) I will have to retube and then calibrate everything correctly to minimize future wear.
I do remember now that people have made statements in the past about the preset contrast setting being way too high on G70 & G90. I guess the next question for people chiming in would be if a lower contrast setting were acceptable for good picture quality and proper gray scale. I would guess it to be yes just due to the high ansi that can these run at.

The second question is even more important if anyone has tube life examples on a machine that was running the proper contrast setting what life did they get. Here again I would guess still lower than the average 10,000 hours again due to high ansi output.

Wow you have a G90 too and with only 600 hours…. Remember the rumor that only 50 G90’s were ever made? I’m starting to think that one was not quite true, many people have been turning up with a G90 on their ceiling. G70’s they are really starting to show up everywhere and for quite the low price, this is one of the reasons for this post.

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I just re-tubed my G70. You dont have to overdrive the tubes just because you can.
Originally Posted by 4101 CRT
Wow you have a G90 too and with only 600 hours…. Remember the rumor that only 50 G90’s were ever made? Pat
no, I never heard that one but the consensus "seems" to be 1000 units for the US and 50 to Europe?

It would seem logical that since the P19 tube was used in many different machines if you set them all to the same light out output they all would last the same amount of time. Just turn your contrast down and your Sony G model tubes will last longer. the nice thing about Electrohmes is if you do a re-intialization (full re-set) they default to 50. Maybe Sony bumped theirs up as a marketing tool.

I know if you set a Marquee to contrast 80 it will wear the tubes just as quickly, gauranteed.
I read that around a 1000 G90's were made. My G90 has a serial number in the 500's and I've seen other units for sale with 20006XX SN. Compared to the BG808S, the G90 puts out a more saturated image even at lower brightness and contrast settings, even with the NEC color-corrected lenses I was using. The settings can be dropped a lot and still produce a great image, whilst at the same time extending the longevity of the tubes. Others may have a better take but I think the G90 will always push its tubes harder than other brands in order to achieve its level of performance.
The G90's from the factory have the G gain set to 255, which is max. This is one reason that the G90's prematurely wear the G tube, This needs to be set at 225 or so and the grey scale readjusted. This cut's way down on the wear and puts it into a more normal curve with other CRT's.

G70 is the same except it's the B that has been set to 255.

Originally Posted by draganm
no, I never heard that one but the consensus "seems" to be 1000 units for the US and 50 to Europe?
Last I heard there were even still something like 100 unsold (FHV or something like that has them for sale), so I think the higher number sounds reasonable.

1000 or so G90's built sounds better for the numbers we see on the resale market, still quite low if every AVS member wanted one:)

Part of owing a large Sony unit is the brightness and resolution it can resolve, simply reducing brightness and contrast takes away from what we are trying to buy. It does sound like Sony wanted to make their PJ picture POP by setting gain at the max and achieve a deeply saturated picture at the tubes expense. Certainly good advice for all the new G70 users to check and set their gain during an install, additionally purchasing a G unit by the stated hours alone and not a picture of the tubes may not be a good idea. 3000 hours on one of these units may not compare to what we are used to seeing on a different projector.
Setting the Green gain at 255 has nothing to do with Saturation - it's just raising contrast higher again.

Saturation is a function of the source.

If you get a G70/90 with good tubes, just run it at a reasonable contrast level (like other projectors) and you will get the same life as others.

But I would assume all 2nd hand G70s/90s to have toasted tubes, and for my usage, I would consider 5000hrs max life for the tubes.
Saturation, who said anything about saturation. I said that the G gain (drive level) is set way to high from the factory and that is what is causing premature wear on the G90's G tube. Not the R tube nor the B tube.

I'm not guessing at this, I know it for a fact and have monitored the wear on NEW P19's I installed for over 2000 hrs after lowering the G Gain to 225. The wear is now almost non existant and I run the contrast at 80 (factory default) and have the grey scale set there. Yet I can show you many G P19's that had the factory setup (255 G gain and 80 contrast) that have less than 1000 hrs on them and exhibit quite a bit wear.

Gain and contrast have a direct bearing on each other.

No, not you Terry :). 4101 was mentioning Saturation, which is not an applicable term here.
Opps, sorry Mark, been one of those days and I didn't read above......sorry.

Perfect Terry that’s what I want to hear not only a reason for the short life but a fix for it and better yet confirmation from someone watching one over time.
Terry I don't understand why you prefer to reduce the gain rather than the contrast. Correct me if I'm wrong, but it seems like it's 2 different ways of accomplishing the exact same thing.
I just looked at my tubes thru the lens' with a flashlight. As best I could tell, using Curt's rating system,the green tube rated a 7, the blue tube an 8 and the red tube a 10. I acquired the G70 with 6K hours on it. I accidently nuked the green tube at 7K (it rated about a 7 or 8 at the time)) and replaced it with a green tube that had over 4K and no signs of wear. The PJ now has 10.5K hours of use, which means the green tube has over 7K, and if the blue and red have never been changed (never by me), they have 10.5K.

I run the contrast at 70 for my HTPC and 65 for HDTV. I have the gain set at max (blue tube at 255). This puts it right at the threshold of blooming, if not slightly blooming.

My color balance doesn't seem to have changed at all, although I have bumped the red gain down a bit. If the brightness has diminished, I didn't notice it because it happened over such a long period of time. I would think that it would have to be dimmer. Again, not sure because of the amount of time involved, but I think the focus is not as sharp as it use to be, although it's still good.

I truly think the tubes have a lot of quality viewing time left in them. 5K, maybe 7K if I get lucky. As others have pointed out, I don't think this is has anything to do with G70s. I think this shows that P16s can last a long time if run at a reasonable levels.
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Originally Posted by Chuchuf
The G90's from the factory have the G gain set to 255, which is max. This is one reason that the G90's prematurely wear the G tube, This needs to be set at 225 or so and the grey scale readjusted. This cut's way down on the wear and puts it into a more normal curve with other CRT's.

G70 is the same except it's the B that has been set to 255. Terry
Terry-- I have the later firmware that doesn't allow me to adjust the G2 on my G70. I run my the unit with a 56 and 35 contrast/brightness settings in a total light controlled HT, and have an awesome picture on a HighPower screen. I'm running my gains in white balancing at R-223, G-224, and B-225. My unit started with only 178 hrs, and I now have about 700 hrs, and still have pristine tube faces.

Are you suggesting that there other settings I should be cranking down individually for each tube? If so, where do you access those setting adjustments in the menu??
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I run My G70 at 80 contrast for all 16:9 video and 72 for other aspect ratios.

Terry set this pj up two years ago. There is nary a hint of tube wear.


One benefit of reducing the contrast with the gain adjustment is as the tubes wear, the color balance can be corrected by increasing the gain. If the gain is maxed out from the get go, that just leaves the G2 if the firmware version even allows.

Only the blue gain is maxed out (because it's the dimmest). You adjust the red and green gain to calibrate the color balance.
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