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[Jim Neighbors]

Recently our projector is starting to have a problem.    You can see what looks like a shadow(or double slightly offset) of anything displayed on the screen. It really shows up black words with a white background are on the screen.    We tried to focus to projector to see if that was the problem,  it wasn't,  then disconnected the computer from the scaler and went direct to the projector but no change.    I don't have the make or model numbers with me right now, but can get them if it would help.   we are looking for some ideas of what to check before we actually try to get to the projector.  It is mounted in the ceiling of our church about 30 feet in the air and we will have to rent/borrow a lift to get to it.

thanks for any help offered.

Jim  

[Brad Weber]

Knowing the models would help.  If you can't get the specific models, then at least knowing what kind of projector (LCD, DLP or CRT and for LCD and DLP, single chip or three chip) would be beneficial.  Also, what cabling is used (manufactured VGA, bundled RGBHV coax, etc.) and how long is the run?  Does the ghost image relate to a specific color or is it just a ghost image of whatever color the main image is?  If this problem just started, have there been any power outages or any changes to the system?  

It could be as simple as an electronic registration or clock/phase issue with the projector settings, which are typically adjustable through the remote.  Projectors can drift over time and need to be "tweaked", that is pretty normal.  Also make sure to see if the problem changes after the projector runs 15-30 minutes, you really want to adjust projectors when they are in a normal operating mode as the heat the generate internally can cause optics and other elements in the projector to expand differentially.

[Jim Neighbors]

the projector is a Optoma EP739 2300 lumen XGA DLP.  The cable run is approximately 150 feet and there is a Altinex DA1908SX amp in the loop.   The installed cable is VGA

The ghost image is the same color as the main image.   There have been no changes to the system to my knowledge.   The problem still exists once the projector is warmed up.

Can you explain a little more on the electronic registration and clock/phase issues and possibly how to check these with the remote?  

thanks for the help so far.

[Brad Weber]

I'll try to help, but I have no direct experience with that projector so others may be able to offer help there.

I would normally think that the cabling is potentially a problem.  150' is a very long run for typical VGA style cable, level losses and sync issues would not be at all unusual in this situation, which could be related to the problem you noted.  However, it sounds as though the problem did not exist for some time and only appeared later.  This would seem to indicate that something has changed.

I would first start with the computer and scaler.  Are they both set to provide a 1024x768 output?  Both the projector and scaler can handle higher resolutions, but 1024x768 XGA is the native resolution of the projector and where it will provide the best image.  So setting the computer and scaler to provide a 1024x768 resolution image with 60-85Hz refresh would probably work best.

I would also try connecting a flat panel display directly to the computer and scaler outputs and verify that the ghosting or double image is not present at those points.  If possible, it would help to also do this with the cable feeding the projector at the projector end, trying to verify that the problem is projector related and eliminating other possibilities.

Like I said, I don't know that particular projector, but looking at the Owner's Manual there seem to be a couple of adjustments that might help.  I am assuming that the throw distance and physical setup are correct since it seems that the problem did not always exist.  First, make sure you have the scaler image up on the screen.  Before anything else, you might want to try the Auto Image function on the projector control panel and the Resync function on the handheld remote.  If those do not help, then try selecting "Menu" on either the handheld remote or the projector control panel, which will bring up the projector settings menu.  Use the arrow and "Enter" keys to select the Image-II menu.  This menu includes Frequency and Tracking adjustments, using the arrow and "Enter" keys, try adjusting those for the best image.  Once you have those set, select "Menu" to go back to the Main Menu and then "Menu" a second time to save the settings and return to normal operation.

[Jim Neighbors]

thanks for the advice Brad.  We are going to your suggestions this evening after worship team practice.

[Brad Weber]

Jim,

Were you able to resolve the image problems?   Hoping the absence of recent postings on this means you did get it resolved.

[Jim Neighbors]

sorry for not posting sooner,  but......we did get the problem fixed (we thought) for a while when we made some of the changes.  The problem has returned and we are looking at a few more things.   We have some kind of signal amplifier between the scaler and the projecter that may be part of the problem.  

thanks for all the suggestions    

[Doyle Souders]

Jim,  it is important that you check some of the things that Brad has mentioned above.  The key item is to connect a monitor right at the output of you scalar to see if the shadow or ghosting  is present there.  If not then you know the problem is either in the cabling or the amplifier.  The most common cause of a shadow/ghosting is reflections on the transmission line.  Essentially the signal is traveling down the line and it hits an electrical discontinuity and is reflected backwards on the line.  It travels all the way back to the start and again is reflected back towards the projector.  It arrives at the projector later than the original signal and appears as a shift.   Poor or loose connections on the cable or a problem ampifier would be the first suspicion.  But again, diagnosis by elimination is the best way to localize the faulty component.  

..Doyle

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