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ICinRGB
Joined: 01 Aug 2007
Posts: 15
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| Posted: Mon Mar 20, 2017 4:53 pm Post subject: Marquee 9500 brightness flicker |
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My 2002 9500LC has an unstable brightness or G2 level and it's been this way the whole time I've owned it, about a year. At times it will be stable but most of the time it fluctuates between, I'd say 10-50% brighter than its current setting, making blacks dark grey, flickering up to light grey. Lately the picture will shift to the left a little while the fluctuations are occurring and be slightly out of focus.
Parts I've swapped out, but only briefly:
CLM
VIM
HVPS
Focus Board
Ran without ACON and Contrast Modulation boards
I've insured that all tubes are grounded and the power jack it's connected to is grounded as well. I've also tried running with each of the tubes disconnected one at a time to rule out a neck board or tube malfunctioning issue. I run it without a case and it always seems cool so I don't think heat is the issue.
I love this projector and really want to to find a solution, any help is much appreciated!
Thanks,
Tony
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Mon Mar 20, 2017 5:37 pm Post subject: |
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The observation that the picture gets slightly out of focus with the brightness change indicates a G2 issue. You are sniffing in the good direction, since G2 control is originated on the CLM and is controlled on the VIM, and takes effect in the HVPS. A connection problem between VIM and HVPS could be suspected as well - sign of an old glycol leak?
_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB, VIM-DB
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ICinRGB
Joined: 01 Aug 2007
Posts: 15
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| Posted: Mon Mar 20, 2017 5:47 pm Post subject: |
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Thanks for the response gjaky, and for the info. It hasn't had a glycol leak since I've owned it, but i did find a little glycol on the focus board when swapping parts around that I cleaned and resolved an unstable h-size issue. I haven't seen glycol anywhere else in the unit. Ok, I'll inspect and try to clean the connections you mentioned. Thanks again!
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Mon Mar 20, 2017 6:05 pm Post subject: |
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Use isopropyl alcohol to flush out under the 8 pin chip of the motherboard that sits vertically under the tubes that the main motherboard connects to. One tiny bit of glycol under that, and that can cause the exact problem.
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ICinRGB
Joined: 01 Aug 2007
Posts: 15
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| Posted: Mon Mar 20, 2017 7:18 pm Post subject: |
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Curt, will I need to disassemble the projector to access that chip?
Thanks,
Tony
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Mon Mar 20, 2017 7:59 pm Post subject: |
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| ICinRGB wrote: | Curt, will I need to disassemble the projector to access that chip?
Thanks,
Tony |
As you could imagine that chip is located at the least accessible part of the chassis, so yeah you have to disassemble it pretty much, unfortunately.
_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB, VIM-DB
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ICinRGB
Joined: 01 Aug 2007
Posts: 15
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| Posted: Mon Mar 20, 2017 8:09 pm Post subject: |
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Ugh. Sounds like I have a weekend project. Does anyone have a pic of this 8-pin chip? I haven't delved that deep into this projector yet.
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Mon Mar 20, 2017 8:11 pm Post subject: |
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If you remove the CLM and the boards over it (CMM and ACON - if you have) you can see it through the opening.
_________________
projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB, VIM-DB
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ICinRGB
Joined: 01 Aug 2007
Posts: 15
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| Posted: Mon Mar 20, 2017 8:15 pm Post subject: |
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Oh, so the backplane. Ok, I'll get to work, thanks!
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Mon Mar 20, 2017 10:26 pm Post subject: |
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You can actually access it when it's floor mounted by taking out the red and green tubes only.
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lydmann
Joined: 12 Aug 2006
Posts: 56
Location: Norway
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| Posted: Mon Nov 06, 2017 8:15 pm Post subject: |
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I have same issue on my 1209/2, except the focus is not affected and Picture is not moving. but when I use blanking, the g2 is increasing-
Can it be the plug to the neckboard which need cleaning? Or is it gasy tube?
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