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Discussion Starter · #1 ·
I have the following setup:


Display Device:


1992 Electrohome ECP 4100 CRT Projector


Input Source:


RGBS to VGA Convert box Inline 2080


HTPC:


1.2 ghz Althon

7500 ATI Radeon All in wonder


Power strip at 800x600 @ 85hz refresh rate.



Randomly the image will dim (no go away completely or lose color) but dim, then 6-8 seconds later restore its brightness, then 6-8 seconds redim, and so on. It will then randomly stop and be fine for a random time (minutes to hours).


This is the case no matter the channel (via ati MMC 8.1's tv) or via dvd (via ati MMC 8.1's dvd).


Any suggestions welcome!!!!!
 

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Sir


You need to determine if one color (such as green) is dimming or is it all three colors equally. There are well known issues with tarnish on video harness connectors where one color can cut out, and issues with capacitors failing on the video control module. All colors dimming in unison is a bit odd but could be an issue with an input card or a power rail from the low voltage supply.
 

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I had that problem as well. With me it was a bad pot on one of the neck boards. tap it or adjust your R8 and see if you get the problem. you might have to replace the neck board.
 

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Discussion Starter · #4 ·
Tim, thanks for the suggestion.


I will try and look down each crt when this happens again. However, since I posted this it has not happened. (the whole car & the mecahnic thing).


PiDD, Thank you for sharing your experience.


I am a newbie and I know where the power deflection boards are, so I assume the neck boards are on the very back of the tube.


Could you describe to me where R8 is at?


I recently purchased a 'parts machine' (another ecp4100) because my HVPS went bad (if you search for the thread you'll see I made a webpage w/ pics about how to change it)., so replacing / testing replacing parts is no big deal.


BTW if anyone is using Guide Plus from ati check this out.
 

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Discussion Starter · #5 ·
Ok, I waitied for this to happen again.


It started happening during monday night football so my first thought was that it was just the green tube.


After checking I can see the blue and red tubes brighten and darken with the other tubes.


It is like the brightness is jumping up by like 1 or 2. I can see the normally bright greens (the grass on the field) become washed out when the screen goes bright.


So far I have only been able to replicate this while watching footbal (UGH!).


Anyway, As I have a back up model:


I am going to try swaping input cards and see if that fixes the problem.


If that does not fix the problem, does anyone else have a suggestion?
 

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Discussion Starter · #6 ·
Ok, I swapped out the Video Control board with a known working one and the problem remained. Therefore I am ruling out this option.


Can someone tell me elaborate on exactly where the neck board is and exactly where R8 is on that neck board?


Any other suggestions welcome!
 

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The input card is either the last or second last card at the back of the machine. It's the one you connect your video signal to. The neck board is the small card at the rear of the neck (on each tube). There are two small

pots on each card toward the bottom. One is R5 and the other is R8.
 

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Discussion Starter · #9 ·
Sorry What I should have said was I swapped out the input card as well, an so it too can be eliminated.


Thank you for the information about R5 and R8, I will look into it further.


Again, thanks for you help/time/suggestions.
 

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Discussion Starter · #10 ·
Ok using the switches between the blue and green tubes I cycled thru having only one of each color on. I did this to confirm that it is infact happening on all three colors.


Futhermore, after I located R8 and R5 I tapped / adjusted them on the blue and red neck boards and no dice.


I do have another ECP 4100 just for spair parts (its how i got my HVPS) so please feel free to suggest swap outs (other than HVPS).


Thanks for all of your help.
 

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Swap out everything, one board at a time..:)


Curt
 

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Have you swapped the source or the VGA convertor thingy?


Might not be the pj at all.


Just a thought :)
 

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I think you're banging into beam limit - back off your contrast about 2 notches on the on-screen scale and see if problem goes away. If so, you're asking for more brightness than the PJ can give and running into beam limit - if not, swap the bias module - it's not a neck bd problem with all 3 CRT's doing it.

Incidentally, it could be outside the PJ (problems with the scaler and macrovision? - it causes this effect....).
 

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Discussion Starter · #14 ·
Mark: I have not swapped out the VGA -> RGB converter box because I do not have another one to test with. Unfortunally this means it will be the last item that I change.


Mike: I turned down (2 notches for each) the Contrast to 3 and the Brightness ~5.5 to but the problem still persists.


I will locate and swap out bias modules between the projectors when I get a free moment (work is really bad right now). This weekend at the latest.


Oh BTW, since I'm running HTPC as my only source, I am sure its not macrovision. I will hook the HTPC up to a crt monitor this weekend just to eliminate the video card.


Curt: Great advice, I think I am about to be at that point and just dedicate a weekend to 'rebuilding' my precious. Would you have any suggestions for starting points?


Again, thanks to everyone in the CRT forum, you guys are great.
 

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Discussion Starter · #15 ·
Ok so my weekend was busy and I did not get around to swaping out anything.


Where can I locate the bias module at? I found pictures of it from ecpresource.com but could not locate the board it self.


Any other suggestions are welcome.


Thanks!
 

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Hi,


The bias module is the board between green and blue tubes, the one where you set G2 and focus.


Guys, I've a similar problem, in my case, the ECP works fine for about an 1/2 to one hour or so after power up, but then the picture dim quite quickly to full dark (nothing visible on all thres tubes)... I switch off and then back on again, it does it the same but quite immediatly... I've to wait a bit for having it "normal" again.


--Patrice
 

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Guys!


Two things are likely to cause variations in black level; the control board could be sending unwanted changes in brightness values to the neck boards, or the G2 level from the high voltage power supply is varying; good hunting. Other voltage variations from the lvps are a possible third cause, haven't seen that, just a hunch.
 

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Hi, Thanks for your answer... Seems I'm looking for an ECP HVPS... If someone have it ;)


--Patrice
 

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Discussion Starter · #19 ·
OK here is an update on whats happening now:


1. It now gets way to bright (instead of dark)

2. It does not do this on the windows desktop

3. It does not do this while playing Mpeg's / Divx's in windows media player.


4. I have removed and reinstalled the ati software and it did not help.


5. I installed the newest video driver and newest direct x 9b and it did not help.


In light of these facts, is it still the HVPS?


I mean why would it do it while playing tv but not other media files?


Also I took the tv out of full screen and it only gets bright in the TV window, not on the desktop.


Any ideas?


Anyone got a HVPS for sell?
 

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Discussion Starter · #20 ·
FYI:


I belive that this is being caused by the capture board on the video card being bad.


I hooked up a VCR to the card via composite (RCA) jack and the problem is non existant. I will try a video card swap out and see whats up.


Maybe the card got damanged some how.
 
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