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antorsae
Joined: 16 Jul 2006
Posts: 297
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| Posted: Tue Nov 17, 2009 7:04 am Post subject: Pulsing brightness at very low IREs - Marquee |
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Hi,
While calibrating one of my projectors I've noticed that if I feed a very low signal (e.g. a small 8 IRE box) the brightness of all 3 tubes pulses (i.e. oscillates). This is not visible with bright scenes but with very very low scenes you clearly see the overall brightness (even what is supposed to be black) pulsing.
I originally thought this was an issue with Mikron boards so I swapped all 3 VNBs by non-Mikron ones and the problem remains. I also tested a V2 Mikrom VIM and a 03 VIM - same problem.
Any ideas?
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HK-Steve
Joined: 15 Jul 2006
Posts: 849
Location: Switzerland
TV/Projector: Marquee 9500, Epson 8100
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| Posted: Tue Nov 17, 2009 10:58 am Post subject: |
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I have seen this before,
The fix was to replace all the pins on the CLM to the DPB and SWB, I replaced with Gold Plated.
Problem gone.
Hope this helps
Cheers
Steve
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antorsae
Joined: 16 Jul 2006
Posts: 297
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| Posted: Tue Nov 17, 2009 11:03 am Post subject: |
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Thanks Steve - I'll try cleaning the CLM pins first. That would be an easy fix!
Could this be related to the AUTO CLAMP feature? I was reading http://www.hometheater1.com/tech/TB96-06.DOC which apparently affects how porches and black level are handled. I have to check if I have a SYNC 2.0 or SYNC 1.0 installed in that PJ.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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antorsae
Joined: 16 Jul 2006
Posts: 297
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| Posted: Tue Nov 17, 2009 11:47 pm Post subject: |
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Thanks Athanasios! I will get the Stabilant 22 and let you know.
Best - Andres
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antorsae
Joined: 16 Jul 2006
Posts: 297
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| Posted: Thu Nov 26, 2009 10:34 pm Post subject: |
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Just received Stabilant 22... now I need to get isopropyl alcohol to make the right mix... I've swapped all boards in that PJ, including HVPS and LVPS and the problem only goes away when I secure the VIM strongly with the screwdriver... it really looks like a connectivity issue on the VIM side... I'll let you all know how it goes.
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Thu Nov 26, 2009 11:31 pm Post subject: |
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How is your pj mounted? (floor or ceiling). I just 'fixed' my buddy's 8500 that would display a rolling image; almost like what you'd see if the pj were fed a signal too high for it to sync too but not scrambled like that. It only did it when the pj was warmed up. We swapped all of my boards, ps's, nb's...everything...and it still did it until we took it down and table mounted it. Then it didn't do it. Hmmm. Curious.
It turned out to be a dry solder joint at the HDM socket that responded to heat flexing of the board when inverted, what with the weight of the HDM tugging at it and all. I modified his FCM and HDM mounting (cages) like I did mine for ceiling mount to correct; what I consider a crappy design. It's amazing that such a wonderfully designed machine would have a horrible retainer solution for those two key components.
Gravity eventually wins out....just look at my hair... it's now a fur collar.  <badum-bum>
I'm positive that has nothing to do with your problem but in the least something to address to make the machine stable. Without securing the FCM and HDM you face the possibility of the blanking and reappearing image thing...which can puff the FCM. (It ain't good for the HDM either but at least it's more robust than the FCM).
_________________
Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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antorsae
Joined: 16 Jul 2006
Posts: 297
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| Posted: Fri Nov 27, 2009 7:18 am Post subject: |
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Greg,
It's ceiling mounted - good point. I also modded the HDM/FGM top cover so it presses the board firmly in the connectors. It did cause issues at one point, but that's now fixed....
Thanks for the heads up!
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HK-Steve
Joined: 15 Jul 2006
Posts: 849
Location: Switzerland
TV/Projector: Marquee 9500, Epson 8100
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| Posted: Fri Nov 27, 2009 8:42 am Post subject: |
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I hold my sleeves up with the red wire straps and crimp lugs, no more movement from the sleeves.
Cheers
Steve
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garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
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| Posted: Fri Nov 27, 2009 6:28 pm Post subject: |
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Yeah, I agree that's an incredibly stupid design for a product that is often ceiling-mounted. I haven't done anything permanent like Steve so I end up wrapping a ratchet strap around the whole beast any time I open the rear heatsink...
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antorsae
Joined: 16 Jul 2006
Posts: 297
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| Posted: Sat Nov 28, 2009 10:54 pm Post subject: |
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Agreed. I have something similar to what HK-Steve uses, only with nylon strands - good idea to repurpose it as an additional grounding for the cages...
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Sun Nov 29, 2009 9:22 am Post subject: |
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| HK-Steve wrote: | I hold my sleeves up with the red wire straps and crimp lugs, no more movement from the sleeves.
Cheers
Steve
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**Pic snipped to save bandwidth**
Oh I like that! So much more elegant than my design. I'm using red silicon 'O' ring material to sling each cage to the mobo. It works extremely well and is very secure but can be a pain in the arse when removing the boards AND the cage(s). Nice work! 
_________________
Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Sun Nov 29, 2009 9:24 am Post subject: |
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| Nashou66 wrote: | it is stupid if you run your marquee with no covers  But once set up is done the covers and rear heat sink hold it all in place. only thing then is making sure you have enough pressure on the boards inside the cage so adding new foam like Andre did is a good idea.
Athanasios |
Yeah I tried that before but I didn't get the warm fuzzies from the holding power of that little dimple in the end of the covers. I could still move the boards up and down (in and out of the sockets) even with new foam and some serious bending of the cover tabs.
_________________
Greg
"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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HK-Steve
Joined: 15 Jul 2006
Posts: 849
Location: Switzerland
TV/Projector: Marquee 9500, Epson 8100
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| Posted: Sun Nov 29, 2009 11:26 am Post subject: |
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Hey Greg,
Thanks for the resize, I did the upload in a hurry.
Cheers
Steve
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Sun Nov 29, 2009 7:55 pm Post subject: |
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Hello
Try padding the covers with 3 or 4 mm layers of duct tape, it is less prone to compress over time.
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