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Author Topic: Projector Searching for Video Signal  (Read 3993 times)

Dave Manini

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Projector Searching for Video Signal
« on: June 03, 2013, 01:11:01 pm »

Effective a few weeks ago our image on screen began intermitently displaying the BenQ Projector logo and looking for a source to display. Is does not display NO SIGNAL. Usual scenario is PowerPoint is running, or DVD, or laptop, and in any given period of time from a few seconds to over 10 minutes the cycle will begin and get worse. I thought it might be thermal in nature since temperatures are up-and it may still be, but it's tough nailing it down.
  I've done the following.
  Sent out my Kramer X-mit and Rcvr modules for test. Came back NPF.
   Bypassing the twisted pair modules entirely to the point of the projector input VGA cable. I'm therefore left with a cable and a projector. NOTE:This system has been operating perfectly for almost 18 months.
   I use two Toshiba PC laptops with VERY similar programs installed. They both failed after a few minutes.  An Apple laptop worked without failure-but I'm confused as to why....esp since the Kramer DVD player would also fail to operate from the mixer board area when hard-wired through the twisted pair networks.
   I've tested all Cat-5 and VGA cables possible (can't get to both ends of the projector run easily)
   I've tried another VGA input in the projector with no success.
   I've run the laptops strictly on battery power to eliminate ground loops.  I suspected a possible background virus scan but I've ruled it out since sometimes the signal is lost in just seconds.
   I'm using a BenQ MX660 projector with Kramer TP-114/TP-120  module pairs.  My switcher is the Kramer VP-728. the DVD-you guessed it...Kramer.  I have appreciated the video quality and by process of elimination it wouldn't appear these items play a part if the problem occurs at the projecter end. 
   Anyone have this issue? All help apprec.  Dave

   
« Last Edit: June 10, 2013, 12:47:57 pm by Dave Manini »
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Dave Manini

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Re: Projector Searching for Video Signal
« Reply #1 on: June 10, 2013, 12:56:41 pm »

     No replies came down the wire for this one so I figured I'd reply to my own post and add a bit to the end of this endeavor.
      A habit of mine is labeling, and separating signal wires from electrical ones.  There was a considerable crossover of cables both at the operating point and the destination. Upon re-arrangment, bundling, and securing them, the problem has not returned.
     Not having actually seen the problem-before trying this fix- holds the door open for a repeat of a missing/searching signal condtion.  One person suggested an 'unwelcome four footed' guest may have had lunch on a cable in the walls, not impossible but unlikely.
   I've ordered a transmitter module with better interference blocking capability which I can place at either end of the installation should the problem re-appear.  Hopefully we can nail it -AND- prove out the fix.   
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Glen Kelley

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Re: Projector Searching for Video Signal
« Reply #2 on: June 25, 2013, 12:03:52 pm »

   I've ordered a transmitter module with better interference blocking capability which I can place at either end of the installation should the problem re-appear.

It has been long enough that I don't remember the specifics, but I had a problem once with Kramer TP transmitters where the transmitter was essentially over-driving the display sync inputs due to a transmission link that was too SHORT.

The symptom was that the display would flash on/off at random intervals. We had to replace the TP transmitters with standard RGBHV distribution amplifiers. The cable runs in this case were very short (less than 50', and were daisy-chained. I doubt this is your case since you mention cable going through the walls, but if the TP modules have an EQ/drive adjustment, you might fiddle with that an see if you get a more stable signal.
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Brad Weber

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Re: Projector Searching for Video Signal
« Reply #3 on: June 26, 2013, 07:29:21 am »

      A habit of mine is labeling, and separating signal wires from electrical ones.  There was a considerable crossover of cables both at the operating point and the destination. Upon re-arrangment, bundling, and securing them, the problem has not returned.
     Not having actually seen the problem-before trying this fix- holds the door open for a repeat of a missing/searching signal condtion.  One person suggested an 'unwelcome four footed' guest may have had lunch on a cable in the walls, not impossible but unlikely.
   I've ordered a transmitter module with better interference blocking capability which I can place at either end of the installation should the problem re-appear.  Hopefully we can nail it -AND- prove out the fix.
It could be an interference problem or a cable damaged after installation, but it could also be as simple as a bad connection or a cable damaged slightly during installation.  An intermittent open or short in conductors, a poorly seated connector and other similar issues could all be affected whenever you move or rearrange the related cables.
 
Another possibility is to check all of your resolutions and refresh rates.  Make sure the computers are sending out something to the switcher that the switcher accepts.  Make sure the switcher output is something the projector accepts and so on.
 
Did you use shielded or unshielded cable between the TP-114 and TP-120?  Either may work by Kramer recommends using shielded cable.
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Dave Manini

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Re: Projector Searching for Video Signal
« Reply #4 on: March 22, 2019, 08:25:28 pm »

It could be an interference problem or a cable damaged after installation, but it could also be as simple as a bad connection or a cable damaged slightly during installation.  An intermittent open or short in conductors, a poorly seated connector and other similar issues could all be affected whenever you move or rearrange the related cables.
 
Another possibility is to check all of your resolutions and refresh rates.  Make sure the computers are sending out something to the switcher that the switcher accepts.  Make sure the switcher output is something the projector accepts and so on.
 
Did you use shielded or unshielded cable between the TP-114 and TP-120?  Either may work by Kramer recommends using shielded cable.
Brad: Did not catch your reply and the solution was in your dialog. Not even sure you will receive this after so long. There were two connectors inline with the projector and one was not completed seated. Never secured the jackscrews on one VGA coupling...barely made contact. Problem was discovered by accident during an upgrade in the same area. Thanks
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ProSoundWeb Community

Re: Projector Searching for Video Signal
« Reply #4 on: March 22, 2019, 08:25:28 pm »


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