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Discussion Starter #1
I was called out today to look at a Marquee that a local installer bought off eBay, and mated it up with a Knoll line doubler (local company, model now discontinued).


Apparently the projector has been losing sync from time to time. Sometimes it works for 2 hours, sometimes it acts up right away.


I saw both tonight. When I came into the room, the projector would roll intermittently with strange linearity problems happening during and just before the rolling began. Then 'V sync out of range" would pop onto the screen. The on screen menus were stable and solid as a rock. Then the pix would snap in and lck perfectly, sometimes for 5 minutes, sometimes for 10 seconds before it all started over again.


Since it was happening with regularity, I suspected a ground loop that was occuring between the satellite dish/cable and the projector. I lifted the ground and the same thing happened.


The installer had already swapped the doubler out, but I am having him hook up his laptop computer on Sunday to eliminate the source as the culprit.


Before I left, the H sync died too, only to snap back into place from time to time.


So:


1) What's the problem

2) Anyone (Tim?) have some boards that I can swap out? I have no 8500 modules currently.


Thanks!


Curt
 

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"...but I am having him hook up his laptop computer on Sunday to eliminate the source as the culprit."


This is where I would also start. For some reason the Marquees are very picky about sync. I've had this same problem with an INLINE line doubler, when using that line doubler it would periodically loose sync and display 'V sync out of range"




I've also had this problem from grounding. Having a 60Hz (same frequency as vert) demon on the green input BNC could cause the internal sync switching circuit on the input (VIM) module to get confused, because this circuit will 'automatically' sync to the following:


- composite sync


- separate H&V sync.


- sync on green


If you select *util 1, 6 from the remote and select the lowest and then highest internal pattern frequencies, and if the display is still stable on both, you would eliminate the deflection boards (vert/horiz) as being defective.


This problem can be a headache, but I don't think it's in the projector.
 

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Guys!


Strange problem indeed. Try pulling out the control board and clean all the pins on the bottom of the deflection processor board, it is mounted on top the CLM; pull U7 on the DPB and clean the socket and contacts also. If that doesn't get it you may need a new DPB.
 

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I also think this might be a source or grounding related problem. I have had this symtom a few times and it has always turned out to be source related. Here's a couple scenarios that have caused my problems....Too strong a sync signal - try terminating the H and Vsync using a "T" and a terminator on one side. No vertical serration pulses and/or positive sync that's positioned a little strangely on the back porch of the signal. Mike's right that Marquees are a little sensitive to sloppy sync so I'd steer in that direction 1st.
 

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Both my Barco 800 and 8500 had this problem. Both problems occured with my HTPC (using a gforce card) Would not sink or would loose sync (rolling screen). Different cableing made no difference. Also the 8500 would loose sync randomly with my dish 6000 HDTV box. The solution for me was to use an extron interface box which resolved all the sync issues for me. Also both proj. had no trouble syncing to the DVDO v1 I had for a while.
 

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Again, see my post above... cmos, it is no suprise that an Extron interface cured your problems, since their components will fix nearly any sync quandry (except for too strong sync level - then they can get screwed up too). Tim and I have both beat the interface drum for a long time for everyone's benefit.
 

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Discussion Starter #8
So Greg, are you reading this thread (the installer here in Vancouver that installed this unit?)


He was going to try a laptop computer Sunday, and I'm dying to see if the suggested remedies cured the problem..


Curt
 

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For what's worth: I had a similar problem (talking about sync) with a Skyworth's VGA output (that appears to be somehow crazy) and a SIM2 Seleco HT200: it was simply fixed with a Barco (not Extron, sorry) VGA interface, that put every sync where it should be.

What don't you post on DLP forum, you could ask? Because I do love CRTs, and just bought a 9500 Marquee to be added to a Barco Cine 7 and a NEC GP-5000 I already own... with a very patient wife!!!

Ciao to everyone: CRT is the way...

Andrea
 
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