Problem with projector during conference

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dnslynn
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Problem with projector during conference

Postby dnslynn » Sun Apr 06, 2014 8:09 pm

I had a problem come up when projecting the recent conference sessions from satellite. During the conference sessions, particularly on Sunday, I would get a rippled water-like effect over a bar about 1/5th the height of the screen rolling vertically through the image. This might be described as a combination of tearing and a hum-bar. Members found it very distracting during the morning session. (I swapped in a lower resolution projector which did not have this problem during the Sunday afternoon session.) What is confusing is that during the material between sessions, this problem was much less apparent, but the moment the live conference session switched in, it became very apparent again.

Did anyone else notice this? Does anyone have an idea what may causing the problem. This is the first time I have noticed it. The projector we use primarily is a SONY XGA VPL-EX7. Our satellite receiver was recently upgraded to the version with the single line LCD display and 4-way menu buttons with enter.

I thought I would check here first before going the the FM group to ask for a replacement projector.

Thanks.

russellhltn
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Re: Problem with projector during conference

Postby russellhltn » Sun Apr 06, 2014 8:53 pm

Depending on the speed it went though the picture, it might well be a hum bar.

How was the projector connected? Did you check the power plug to see if it could have been plugged in backwards? (Most 2 prong plugs are polarized so the only go in one way. I assume there's a reason for that.)
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dnslynn
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Re: Problem with projector during conference

Postby dnslynn » Sun Apr 06, 2014 9:06 pm

It was a three prong plug. I had a 2 prong to three prong isolator and I tried that but it made no difference. Also, I have not noticed this problem before this weekend.

russellhltn
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Re: Problem with projector during conference

Postby russellhltn » Sun Apr 06, 2014 9:42 pm

dnslynn wrote:Also, I have not noticed this problem before this weekend.

Other broadcasts? Or different setups?

It might be worth a talk to some of the higher satellite people to see if they have any ideas.
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mfmohlma
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Re: Problem with projector during conference

Postby mfmohlma » Mon Apr 07, 2014 11:15 pm

We've had this problem for years at our stake center. The STS hasn't been able to isolate it, but it's definitely a ground loop of some sort.

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Mikerowaved
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Re: Problem with projector during conference

Postby Mikerowaved » Tue Apr 08, 2014 12:08 am

Where was the projector getting the video signal from? Composite feed from an RCA wall-jack? VCR? Other?
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mfmohlma
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Re: Problem with projector during conference

Postby mfmohlma » Tue Apr 08, 2014 12:17 am

Mikerowaved wrote:Where was the projector getting the video signal from? Composite feed from an RCA wall-jack? VCR? Other?

I'm pretty sure we're just using the RCA composite jack on the stand.

russellhltn
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Re: Problem with projector during conference

Postby russellhltn » Tue Apr 08, 2014 2:15 am

mfmohlma wrote:We've had this problem for years at our stake center. The STS hasn't been able to isolate it, but it's definitely a ground loop of some sort.

If it's consistent, then it might be in the equipment rack. I've had the filter caps on the modulator go out. When it goes, you'll get a hum bar in the video.
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mfmohlma
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Re: Problem with projector during conference

Postby mfmohlma » Tue Apr 08, 2014 2:03 pm

russellhltn wrote:If it's consistent, then it might be in the equipment rack. I've had the filter caps on the modulator go out. When it goes, you'll get a hum bar in the video.

It's possible. We have stake conference (with accompanying broadcast) this weekend and I know they use the modulator to send signal throughout the building.

If it was the modulator, do you think someone in the FM group could definitively diagnose it and order repair or would they just have to call a contractor off the bat? The reason I ask is if it is the latter, FM will likely push back.

russellhltn
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Re: Problem with projector during conference

Postby russellhltn » Tue Apr 08, 2014 2:15 pm

mfmohlma wrote:If it was the modulator, do you think someone in the FM group could definitively diagnose it and order repair or would they just have to call a contractor off the bat? The reason I ask is if it is the latter, FM will likely push back.


I think typically FM gets support from CHQ in diagnosing things.

Note that if it is the modulator, you'll likely have a loud hum in the audio as well. (You may not have noticed it if you're not using the TV for sound.) The ones that I've had fail have gotten to the point that you can't hear anything else but the hum in the audio.

If you're handy with a soldering iron, it's an easy fix to change out the cap. Although it's not the easiest board to pull and replace. The power supply is in it's own area with it's own PC board.
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