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Hi,

A friend has a 1292 that has a focus problem on the Blue tube.

I think it may be an electronic problem more than a bad tube as all the others including the blue one have no burns and appear to be in excellent cond (I know lots of things can go wrong internally with the tube....but I just need to convince myself).


The projector has low hours on all tubes (He brought the projector with this problem, so we cannot find out if the problem came on gradually or not) so I would like to do some more checking before I commit to telling him to replace the tube.

At this stage I plan to swap the "bad" tube with one of the good ones to see if the problem follows the tube.

If it turns out not to be the tube, does anyone know if there is a workshop manual on the net somewhere for it?


cheers

John:cool:
 

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I'm no expert on this stuff, but are you sure you have a problem with the tube. The blue tube is always appears blurry and is de-focussed slightly from the factory and is noticably less sharp than green or red tubes.


Use the H test pattern and if the focus across it is uneven or you can't make out the H distinctly then you may have a priblem. You then need to narrow down whether it is a optical focus problem(lens) or an electronic focus problem(tube).


With the brightness and contrast to 0(and a pair of sunglasses) look into the blue lens and see what the image on the crt looks like. If the problem is on the tube then check the magnetic focus is adjusted correctly. If the image looks ok on the tube then the optical focus is the problem and you need to check the scheimpflug adjustment(pair of rings with grooves & numbers on it) and also adjust the G1 & G2 focus knobs on the lens. The scheimplug adjustment adjusts the horizontal and vertical tilt of lenses in respect to the crt if say a particular side of image is blurry. If you already have these set on the settings in the book, then try changing them a little to see if it fixes the problem. To get a perfect optical adjustment I have had to set these to different values than the book indicates even though I would swear than my PJ is mounted straight & level. You need to loosen off the 4 bolts that have springs under them to adjust the rings. Note that PJCalc calculates different values than the book. Finally the G1 adjustment focuses the centre of the image and the G2 focuses the corners. Search for "Scheimpflug 1292" and you will find some good info from Guy Kuo etc.


I might just be stating the obvious here...just making sure you haven't missed anything. Good Luck.
 
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