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antorsae
Joined: 16 Jul 2006
Posts: 297
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| Posted: Mon Nov 23, 2009 2:26 pm Post subject: Bad Contrast Modulation Board (Marquee) - Help! |
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Hi,
I was watching a movie the other day and heard small BUM! in one of my PJs but I thought the noise came from outside... At first, the Marquee did not detect the CMM board but after one day it behaved erratically and started smelling like fried electronics; so I stopped everything and found the CMM had two fried resistors (R118):
I am going to fix the resistor, two questions for those Marquee electronic experts:
1) Can I just a 10R resistor instead of two 20R in parallel? If so, what wattage/etc.
2) Any idea as to why this could have failed? I am running a fairly high contrast (75).
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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 Nov 23, 2009 3:13 pm Post subject: |
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1) Yes.
2) Chances are something has shorted out on the board, and the resistor will smoke again. Use 1/4 watt. A properly working board won't smoke the new resistor. I've got spare boards if you don't want to bother to repair that one.
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Mon Nov 23, 2009 3:14 pm Post subject: |
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R118 is the feed for U2 (+5 volt regulator). When it burns, U2 is shorted or there's a short on the +5 volt rail that U2 feeds.
Put a 4.7 ohm 1/2 watt there.
while at it, replace C6 and C8 with 100uf 35vdc electrolytics (really helps the noisy CMM boards).
It's always best to replace the CMM board when this happens.............
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antorsae
Joined: 16 Jul 2006
Posts: 297
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| Posted: Mon Nov 23, 2009 4:01 pm Post subject: |
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Thanks guys!
How much does a working CMM board cost (incl cheapest shipping to Europe and those cap changes MP recommends)?
Regards - Andres
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Mon Nov 23, 2009 4:21 pm Post subject: |
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Something like a CMM I would not put a cost to it.
I have a CMM here that I could noise test and cap up for you, and could probably put it in a USPS Flat Rate Priority box, but It'll have to wait until I do my next shipments.
Not sure what the shipping would be, but It'll be no cost for the board. I'll even through in the caps for your other board.
I also replace those two resistors with 4.7 fusables.
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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 Nov 23, 2009 4:28 pm Post subject: |
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Tested and working, $65 USD incl shipping. Shoot me an email or PM.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Mon Nov 23, 2009 5:24 pm Post subject: |
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| mp20748 wrote: | | I also replace those two resistors with 4.7 fusables. |
Thats the word I was hoping to see.
Last edited by macgyver655 on Mon Nov 23, 2009 5:41 pm; edited 1 time in total
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Mon Nov 23, 2009 5:26 pm Post subject: |
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| Curt Palme wrote: | | Tested and working, $65 USD incl shipping. Shoot me an email or PM. |
Count to 10.........1......................2.........................3..........................4.............................5...........................6..........
........7......................8.........................9......................10...............
Ahhhhhhhhhhhhhhhh 
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Sparky015
Joined: 12 May 2009
Posts: 1185
Location: Cleveland / Akron, OH
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| Posted: Mon Nov 23, 2009 6:18 pm Post subject: |
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| mp20748 wrote: | R118 is the feed for U2 (+5 volt regulator). When it burns, U2 is shorted or there's a short on the +5 volt rail that U2 feeds.
Put a 4.7 ohm 1/2 watt there.
while at it, replace C6 and C8 with 100uf 35vdc electrolytics (really helps the noisy CMM boards).
It's always best to replace the CMM board when this happens............. |
Thanks for the tip, Mike.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Mon Nov 23, 2009 7:43 pm Post subject: |
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is it just me or are D5 and D6 blown open?
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Sparky015
Joined: 12 May 2009
Posts: 1185
Location: Cleveland / Akron, OH
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| Posted: Mon Nov 23, 2009 7:51 pm Post subject: |
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The pic is misleading, but they look fine to me. Those diodes are a bit tricky checking visually
_________________
~Paul
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Mon Nov 23, 2009 8:15 pm Post subject: |
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ok, hard to tell but the glass body looks cracked in that pic.
Also, C6 and C8 are already EL caps, is just the higher value that makes a difference here?
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Mon Nov 23, 2009 8:22 pm Post subject: |
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I higher value would most likely help the power supply feed the amps if using lots of contrast modulation as you approach a roll of closer to 0% at the edges.
Roll of of about 25% is noticeable but acceptable by most standards ( i'm talking about luminosity of the screen). I think i need to do this on the blend since I am trying to hit that 0% roll off mark. During scenes that have lots of brightness you can almost see the luminosity go down on the edges I used the modulation.
I wonder if this is sign of the power supply craping out a bit. the 100uf would give a bit more head room.
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Mon Nov 23, 2009 8:44 pm Post subject: |
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| draganm wrote: | ok, hard to tell but the glass body looks cracked in that pic.
Also, C6 and C8 are already EL caps, is just the higher value that makes a difference here? |
Yes.. the higher value (100uf) capacitors cleans up a slight noise problem that is common on some of these boards. I don't use them and see no real need them in a single setup. We also remove them on the blend setups.
But when using them of if one of my customers use them, I change out the caps and resistor.
Here's why I've asked people to remove those boards if not doing zone contrast:
Those little EL caps are literally eating up after many hours of dealing with the pulses (high frequencies) from the LVPS. When they leak or fail, that resistor usually burns out. If you simply replace the resistor, it will most likely blow again. It's only after replacing the caps does the problem go away, but that's if one of the chips are not also shorted.
I've always thought that the leaky caps caused some of the chips to overheat and short. And that's why i say it's best to replace the board once that happens. And if the caps leak and the resistor does not burn out, the board will usually put some level of noise in the image.
I don't use them in the blends or edge match setups that I maintain.
The same is true with the caps on the Stig board on the CLM. I have a ton of them that's shorted. They also have those tiny EL caps that should not be used in a circuit that has the level of high frequency pulses that are on the Marquee power rails.
They not only should be 105 temp, but should also be a much higher voltage if not.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Mon Nov 23, 2009 8:49 pm Post subject: |
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You dont use them in a blend set up? Really? I can't se how you can not use them. I left all the zones to default and only when I began adjusting the edge
zones did I see an improvement in the blend zone. Maybe because I have an AC blend and not LC but to me I think zone modulation is a must for
Blends. Just my personal observation.
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Nov 24, 2009 3:49 am Post subject: |
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| mp20748 wrote: | | Those little EL caps are literally eating up after many hours of dealing with the pulses (high frequencies) from the LVPS. When they leak or fail, that resistor usually burns out. If you simply replace the resistor, it will most likely blow again. It's only after replacing the caps does the problem go away, but that's if one of the chips are not also shorted. |
that's good to know, I should probably add this board to the package I offer.
| mp20748 wrote: | | The same is true with the caps on the Stig board on the CLM. I have a ton of them that's shorted. They also have those tiny EL caps that should not be used in a circuit that has the level of high frequency pulses that are on the Marquee power rails.They not only should be 105 temp, but should also be a much higher voltage if not. |
Those I already replace, there's 12 of them 25volt 22uf I replace them with 50 volt 22uf 105C. They also used these little things on the Stig waveform, HDM daughter board, and the HDM itself.
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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 24, 2009 10:18 am Post subject: |
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Sorry I have no spare CMM boards.
But as Mike has said, with a couple of cap upgrades,
plus some chip changes, the performance increases are very nice.
Cheers
Steve
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antorsae
Joined: 16 Jul 2006
Posts: 297
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| Posted: Tue Nov 24, 2009 11:11 am Post subject: |
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Thanks Steve!
What chip changes? 
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Nashou66
Joined: 12 Jan 2007
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Location: West Seneca NY
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