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JVC RS56 new bulb not as bright? Optics cleaning required?
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kal
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Joined: 06 Mar 2006
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Location: Ottawa, Canada

TV/Projector: JVC DLA-NZ7


PostLink    Posted: Mon Sep 27, 2021 8:37 pm    Post subject: JVC RS56 new bulb not as bright? Optics cleaning required? Reply with quote


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Hi guys,

I installed a new JVC RS56 bulb last night and it's noticeably dimmer than the other three bulbs that have been in use since 2013 in my machine. I only use official JVC PK-L2312U bulbs.

For reference the first three bulbs needed iris set to -2 in low lamp mode to hit 14 foot lamberts of light output when new (they all behaved identically), but on this fourth bulb I'm having to go into high lamp mode right away (iris set to -5). If I use the same low lamp mode with iris set to -2 on this new bulb I only get 11.5 foot lamberts instead of 14.

I figured there may be an issue with the bulb but now I'm wondering if I need to clean my optics... I know some early models were pretty bad that way but I thought it had gotten better. Anyone with a JVC RS46/56/66 do any cleaning? For what it's worth, I do check the air filter periodically but in the almost 9 years I've owned the thing it's never had anything on it, not even the finest dust.

I'll take a closer look tonight but figured I'd ask first. Not coming up with anything overly useful googling "JVC RS46 (or RS56) cleaning".

Kal

Edits:

Did find this (ironically from this site!), but it's about very early models: http://www.curtpalme.com/forum/viewtopic.php?t=30952

Found this too, but again talks about models before mine: https://www.avsforum.com/threads/an-ol-trick-for-some-jvc-owners.1779201/

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Last edited by kal on Wed Sep 29, 2021 1:09 am; edited 1 time in total
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kal
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TV/Projector: JVC DLA-NZ7


PostLink    Posted: Mon Sep 27, 2021 10:43 pm    Post subject: Reply with quote

Pulled the brand new bulb (only 1-2 hours of use) and it appears there may be a subtle fogging on the optical plate (the glass (?) plate that the bulb points in towards that is permanently installed the projector). Not nearly as bad as this post but there seems to be a bit: https://www.avsforum.com/threads/an-ol-trick-for-some-jvc-owners.1779201/#post-29396889

I've ordered some single use wet lens wipes that are meant for camera lenses and similar. Should arrive tomorrow. Outside front lens has some very subtle dust on it but I'll clean it at the same time. There's a lens cover on mine that closes whenever the projector's not used.

I guess that shouldn't come as a surprise given that the projector is from 2013 and has seen 8700 hours now that there may be some build-up.

I'll re-measure the light output once cleaned. We'll see!

Kal

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garyfritz




Joined: 08 Apr 2006
Posts: 12024
Location: Fort Collins, CO


PostLink    Posted: Mon Sep 27, 2021 11:16 pm    Post subject: Reply with quote

But if it was gradual build-up, the old bulb would have showed it too. You don't think the new bulb off-gassed excessively?
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kal
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TV/Projector: JVC DLA-NZ7


PostLink    Posted: Mon Sep 27, 2021 11:43 pm    Post subject: Reply with quote

garyfritz wrote:
But if it was gradual build-up, the old bulb would have showed it too.

My thoughts exactly.
Quote:
You don't think the new bulb off-gassed excessively?

I doubt it. The previous bulb (bulb #3) was installed in 2018 and showed normal light output (similar to the first two) when I first fired it up. Would seem odd that it did something weird that the first two did not, but you never know. JVC changed suppliers? Something different with the 3rd bulb? Not sure.

Could also be that maybe there's something that built up over the last 3 years to actually have an effect on light output that barely registered over the first 2 bulbs? Seems doubtful. Today I do see a fine film on the optical plate so I'll clean that off tomorrow once I have the proper wipes and we'll see what light measurements I get.

Kal

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wanderer




Joined: 11 Jan 2015
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PostLink    Posted: Tue Sep 28, 2021 2:44 pm    Post subject: Reply with quote

To test you could put your old bulb back in and see if the light output was the same as before. If the light output is the same as before then the PJ and ballast are probably OK and the new bulb is the issue.
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kal
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TV/Projector: JVC DLA-NZ7


PostLink    Posted: Tue Sep 28, 2021 2:56 pm    Post subject: Reply with quote

wanderer wrote:
To test you could put your old bulb back in and see if the light output was the same as before. If the light output is the same as before then the PJ and ballast are probably OK and the new bulb is the issue.

Thanks, but I don't understand that logic. If I put the old bulb back it'll show the same lower light output I measured 2 days ago before I changed the bulb. That doesn't tell help me conclude if the optics are dirty, or if the new bulb is defective, or if there's a PJ/ballast issue. The light output didn't drop all of a sudden with the new bulb. At zero hours it's just dimmer than other new bulbs I've put in.

I'd need a second new bulb (or many) confirm that the one new bulb is defective. i.e. if I try 10 new bulbs and they all measure the same light output then I know it's probably not the bulbs (unless they've all changed), but something about the projector (dirty optics, faulty electronics, etc).

To test the projector, I could also take the bulb and stick it in a different (but identical model) projector. This is trickier as both would have to be set up identically. I suppose if someone else with an identical projector that's been using the stock/OEM bulbs knows what light output they measure when at zero hours, they could test the same way as me and conclude that either the bulb is defective or that JVC has changed the bulbs (i.e. lower light output is expected/normal). I doubt they changed the bulbs however. People would be reaching for their pitchforks. Wink

Kal

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garyfritz




Joined: 08 Apr 2006
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PostLink    Posted: Tue Sep 28, 2021 5:00 pm    Post subject: Reply with quote

kal wrote:
Could also be that maybe there's something that built up over the last 3 years to actually have an effect on light output that barely registered over the first 2 bulbs? Seems doubtful.

That's what I was thinking -- or, more specifically, built up during bulb #3. Bulb #3 went in and had proper output, so everything seemed OK. Then it got dimmer, then bulb #4 went in and it's also dim. That suggests to me either 1) #3 offgassed (or did something) that reduced its output, and #4 suffers from it as well, or 2) #4 has substandard output for a new bulb.

Hopefully your cleaning efforts will bring back the optimal outputs. If so, then #3 may still be usable -- though you may not want to, if #3 is the cause of the dimming!
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kal
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TV/Projector: JVC DLA-NZ7


PostLink    Posted: Tue Sep 28, 2021 5:15 pm    Post subject: Reply with quote

Yeah, that's my line of thinking too Gary. Though reading from others who have done the cleaning on earlier models they mention it didn't help light output usually. We'll see. I'd be very surprised if a cleaning helps. If it doesn't, oh well, I'll just use the bulb as is and may get less life out of it.

#3 bulb is just under the 2900 hour mark (the time at which the projector warns you you shouldn't use it anymore) and I've always heeded that warning. They say you can get to 4000 hours if you run the lamp in low power mode the whole time, but that above 2900 it may stop working, and when they stop working they may actually explode and cause damage. It's probably very rare, but I'd rather not take that chance especially since I tend to run about half the bulb life in high lamp mode to have the light output I like. Never mind that on my throw distance/setup/screen size/screen gain by 2900 hours I'm usually below 10 ftL anyway (too dim for my liking) even on high lamp mode.

While everyone has different want/needs SMPTE recommends 16 ftL, I try and target 14L. If this was HDR it would be a whole other ball game with some people trying to target 35+ ftL it seems! (crazy).

Kal

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kal
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PostLink    Posted: Wed Sep 29, 2021 1:11 am    Post subject: Reply with quote

Cleaned off the very subtle fogging on the optical plate and it didn't make any difference to the light output. Picture does look fantastic as always. Just weird that I'm a few foot lamberts lower out of the gate on this new bulb requiring high lamp mode. Oh well! I'll just enjoy it for what it is. Still putting about 1000 hours/year on to this unit and loving it. Maybe in a few years I'll consider one of their new laser projectors like the NZ8: https://www.us.jvc.com/projectors/procision/dla_nz8/

Kal

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garyfritz




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PostLink    Posted: Wed Sep 29, 2021 4:16 am    Post subject: Reply with quote

8k, crazy. If you had a giant 12' wide screen, the 8192 pixels would each be less than half a millimeter wide. Seems like overkill. 20/20 vision can resolve about 60 cycles (black & white line pairs) per degree of arc. If you sat at 1x width = 12' = about 3600mm, one degree would be about 3600 * tan(1°) = 62.8mm. So 20/20 vision can resolve about 1 black & 1 white per 2mm! Only 1800 black/white pairs across the screen. Wow. So yeah, I would think 1 pixel per 1/2 mm is a bit more than you need. Seems like 4k would be more than enough. But of course the AV companies want to keep selling projectors ...
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kal
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PostLink    Posted: Wed Sep 29, 2021 12:08 pm    Post subject: Reply with quote

Yeah, I know. I have no interest in the 'pseudo' 8K (the panels are "only" 4k). Even 4K I don't really care about frankly on my 110" screen sitting 11-12 feet back. It's more about the colour gamut, HDR10+, light output, laser light source, etc.

Kal

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nettwerkjohn




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PostLink    Posted: Sat Oct 02, 2021 11:59 pm    Post subject: Reply with quote

i've seen the n5, n7 and n9. the n7 is very much the sweet spot. i want one, but considering the stash of new lamps i have for my 900, i can't justify the change.
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kal
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TV/Projector: JVC DLA-NZ7


PostLink    Posted: Sun Oct 03, 2021 3:49 pm    Post subject: Reply with quote

nettwerkjohn wrote:
i've seen the n5, n7 and n9. the n7 is very much the sweet spot.

I’m assuming you mean the NX bulb based series. I was talking about the new NZ laser based series which isn’t shipping (yet) and was just announced. I’m sure the NX are I nice too, but if I’m to jump in the next few years it’ll probably be laser.

Kal

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nettwerkjohn




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PostLink    Posted: Mon Oct 04, 2021 7:00 pm    Post subject: Reply with quote

kal wrote:
nettwerkjohn wrote:
i've seen the n5, n7 and n9. the n7 is very much the sweet spot.

I’m assuming you mean the NX bulb based series. I was talking about the new NZ laser based series which isn’t shipping (yet) and was just announced. I’m sure the NX are I nice too, but if I’m to jump in the next few years it’ll probably be laser.

Kal


Kal

correct, the NX.

Seen a couple of Sony lasers - very nice but the NX5 was a step up. the hdr is incredible.

Funnily enough I'm thinking of moving away from the JVCs towards a barco DLP. Currently looking at the Loki.
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digitalayon




Joined: 02 Mar 2009
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PostLink    Posted: Thu Oct 21, 2021 3:04 pm    Post subject: Reply with quote

The issue with JVC would be the so called "filter" that they use. These always get dirty. JVC really did a crappy job on these filter thinking. I wonder if anyone has tried a real filter to go on one like a cloth sleeve.
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AnalogRocks
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TV/Projector: Sony 1252Q, AMPRO 4000G


PostLink    Posted: Thu Oct 21, 2021 5:20 pm    Post subject: Reply with quote

digitalayon wrote:
The issue with JVC would be the so called "filter" that they use. These always get dirty. JVC really did a crappy job on these filter thinking. I wonder if anyone has tried a real filter to go on one like a cloth sleeve.


In all my JVC's I own ( early and mid 2000's models ) I changed the stock disintegrated foam filters to a piece of flat furnace filter. Works much better. I've blown pieces of the old foam filter out of the bulb heat sync along with lots of dust.

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kal
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TV/Projector: JVC DLA-NZ7


PostLink    Posted: Thu Oct 21, 2021 8:08 pm    Post subject: Reply with quote

Strange as the small air filter in my RS56 has never had anything on it (it's always spotless) and it's also not foam. It's a thin mesh of plastic.

Sits here near the bottom:


They say to rinse it:



But I've literally never had anything on it to clean off since I first installed the projector in 2013. Thousands of hours on it too.

Kal

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kal
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PostLink    Posted: Thu Dec 14, 2023 9:36 pm    Post subject: Reply with quote

Resurfacing this old thread as I've now been on JVC PK-L2312U bulb #5 for ~600 hours. This is also an official JVC bulb from my dealer and like bulb #4 this one also is much dimmer than previous ones at the same settings. I've had to go to high lamp mode with the iris all the way open (setting of '0') far sooner than before to maintain 14ftL.

Bulb #5 was a bit better than #4 when new however when I tested on low lamp / iris 0:

New Bulb #4: 11.5 ftL
New Bulb #5: 12.2 ftL

But Bulb #4 kept it's brightness longer than what #5 is at now. At the same ~600 hours bulb #4 was at 14.5 ftL on high/iris -3, while bulb #5 on high/iris 0 gives 11.9 ftL. Bulb #4 was closer to 1800 hours before hitting that level at high/iris 0.

So I'm just under 12 ftL now with only 600 hours on the bulb which isn't great. 12ftL looks fine but it'll only get dimmer.

Wanderer may have been on to something above when he mentioned putting in the old bulb to test, as it made me realize that a good test would be to reinstall a MUCH older bulb to test today and compare with my previous readings from years ago.

So I did that: Went back to bulb #2 and #3 from 5 and 8 years ago and measured a 10-14% drop today as compared to back then. Not a massive drop but this means something that changed in the projector or in my cheap light meter (which I frankly don't trust for super-accurate readings - I have this model from ~10 years ago: https://amzn.to/4aoSaZl).

I'm thinking that something in both the bulbs and projector may have have changed as cheap meter aside, I can tell things aren't as bright anymore even without a meter at the same settings.

I again cleaned the glass plate where the lamp faces inside the projector as well as the front lens (neither was dirty) and like before, no difference in light output.

I don't really relish the idea of opening up the light path (optical block) to take a look let alone try and clean it as there's stuff in there that you definitely won't want to touch.

This projector uses 230W PK-L2312U Ushio bulbs and you can buy these really cheap off eBay or similar (especially if you get the lamp only without the housing) but who knows you're getting or if it's legit.

Kal

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kal
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PostLink    Posted: Mon Dec 18, 2023 3:31 pm    Post subject: Reply with quote

The more I read about this, the more I think it's simply dust buildup over time. I do have over 11,000 hours on this thing.

After the holidays (when people aren't using the thing) I'm going to dive in and gut the thing. I may even go as deep as cleaning inside the optical block. This is not for the faint hearted as there are some very thin precision mirrors that you can easily break if not careful when disassembling/reassembling. Getting that thing apart and back together is almost like precision surgery as these things are precision assembled. If anything in the optical block ever needs to be fixed/replaced, JVC simply replaces the whole unit (very expensive). The RS46/56/66 service manual has it as one SKU.

Check out this thread by Guy Kuo (whom some may remember from our CRT days):
https://www.avsforum.com/threads/dila-x-series-lamp-iris-mod-optical-block-cleaning-and-blackening-to-improve-contrast-graphics-heavy.3207419

The thread deals with many subjects including modding to improve contrast, but you can see how you get into a JVC DILA to do optical block cleaning. Different model than mine of course but the ideas are similar.

This thread deals with cleaning a RS46/X35 so it would be very similar to my RS56, but the thread doesn't go into much detail as to how to exactly do the disassembly/cleaning:
https://www.avforums.com/threads/jvc-d-ila-pink-magenta-stripe-fixed-x35-in-this-case-pictures-of-inside-optical-block.2126897/

Apart from the difficult disassembly/reassembly, knowing what to clean and how is very critical are there are polarizers that you cannot touch at all otherwise you destroy them. Lots of research to be done.

Kal

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barclay66




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PostLink    Posted: Mon Dec 18, 2023 4:28 pm    Post subject: Reply with quote

Would using pressurized air be an option? If the dust isn’t too sticky, then it could do the trick without risking any damage to surfaces. If the machine has been used in an environment with smokers, it won’t help much though…
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