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Nec XG not locking on to correct frequency

 
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Makieo



Joined: 30 Jul 2007
Posts: 17


Posted: Mon Jan 07, 2008 12:21 am    Post subject: Nec XG not locking on to correct frequency

I got this projector from an auction about 4 months ago. Since then it has had a problem when it is first plugged in. The projector fails to clamp on to a signal properly (I think). The resulting image reminds me of an oscilloscope before you match the frequency. Here are some videos of the problem:

Displaying a source.
http://www.youtube.com/v/hBbtg8TSRto
- The problem is not at the bottom of the screen

Displaying a dot test pattern.
http://www.youtube.com/v/IGLQBwCfB_w&rel=1
- Compressed badly. the dots are not arranged correctly and scroll by.

Every time before now the projector would eventually lock on to the signal. Once it has locked on to a signal it did not have a problem locking on to any signal as long as it remained plugged in. However, once it is unplugged the problem comes back. Up until now its only been unplugged twice.

The projector randomly changes frequencies. The frequencies from the above videos were (fh) 28.14 khz (fv) 216 hz. Every few minutes the projector will display the image correctly and the frequencies will be more reasonable ie 28.14 khz 60 hz.

I just mounted it on the ceiling last night. Of course it was unplugged and the problem came back. This time however its not fixing itself. The problem completely slipped my mind, if I had remembered the problem I probably would not have mounted the projector until it was fixed. I guess its coming back down Crying or Very sad

Has anyone seen this problem before? Any help would be greatly appreciated.
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Mark_A_W



Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia

Posted: Mon Jan 07, 2008 1:31 am    Post subject:

Problems with syncing are probably the Oscillator board (in the card cage at the back).

But the fact that some of the image is ok in the first movie, makes me suspect the V-drive - as your horizontal deflection appears almost ok.

The 2nd movie looks like a bad Oscillator board to me.

It could also be a bad System board, but if all other functions work ok (except the reporting of frequency) then it's probably ok.


If I had that projector on hand I'd swap the oscillator board first, you can do that without dropping the projector (same with V-drive actually, but not so much fun..).

But it could just be a bad connection at the back - the "V" connection.
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Makieo



Joined: 30 Jul 2007
Posts: 17


Posted: Fri Jan 11, 2008 8:22 pm    Post subject:

Sorry We have been really busy.
We were able to get the internal menus and s-video to work.

We do not have any other cards to test with so besides re-seating the cards what should we be checking for a problem.
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Mark_A_W



Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia

Posted: Fri Jan 11, 2008 9:43 pm    Post subject:

I already told you, the Oscillator board.
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dbaisey



Joined: 09 Mar 2006
Posts: 821
Location: Southern Cal LA / Seattle WA

Posted: Fri Jan 11, 2008 10:20 pm    Post subject:

What exact model of XG?

With a RGB source connected above 30 kHz does the on screen display start a scrambled menu across the screen? You can use most any of the menus to check this.

With the signal removed eliminating source freq bring up a menu and see if its scrambled.

This can be a two fold problem but I'm leaning towards the system board first and or oscillator board. Doug
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Makieo



Joined: 30 Jul 2007
Posts: 17


Posted: Sat Jan 12, 2008 3:12 am    Post subject:

Doug,

The projector is a 1350. I feed a signal over 30 khz and the menu was scrambled along with the picture. When I unplugged the source the projector flashed no input and unregistered signal which was not scrambled.

If it is the system board how much can I expect to pay to get a replacement? Has there been any luck in repairing system boards with the scrambled mess problem?

Thanks for your help.
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Mark_A_W



Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia

Posted: Sat Jan 12, 2008 5:15 am    Post subject:

Hammerhead Tech or Ebay. Oscillator board will probably be reasonably priced....system board = good luck.

I still reckon if all menu functions work (this does not mean the menu is stable on screen, just that the functions work ok), then I would try the (cheaper) oscillator board first. And you won't lose ALL of your settings like a system board - which would need a full white balance and convergence, if you can't write ALL the numbers down first.
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