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Discussion Starter · #1 ·
Please excuse the newbie question ...


I'm going through the setup on my 1251q and learning about projectors at the same time. I've taken the lenses off the projector and was going to center the rasters and the images on each tube before reinstalling the lenses and continuing on with the setup.


The question is, when I have the PJ on with the contrast down and the brightness at about 20 I can clearly see the blue and green raster, but I can't see the red at all. Is this normal? I thought I should be able to see all of them equally. The red tube lights up just fine when displaying images or test patterns, but just can't see the raster to center it. Each tube has a bright horizontal line at the bottom of the raster.


Any info would be appreciated.


Thanks,

Karl
 

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It sounds like the red G2 is set differently (don't worry for now - you'll learn about this later).


Is it visible if you keep pumping up the brightness? 20 is really low...


Otherwise just centre the image with Zone 1 (I set RGB shift at 128 beforehand, I'm pedantic), don't worry about centering the raster.

The raster moves with the image on a 12xx Sony, there are no centering magnets.


The bright line is normal, it is the Automatic Cathode Bias (AKB) line, part of the normal operation of the projector.


Sounds like you are making a very good start. After you have the images centered - just centre the image L-R and Top to Bottom, I would suggest that you shim the metal CRT spacers and bring the crosshairs up and line them up on the screen - there is a number of threads on this, some recent.


Mark
 

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Discussion Starter · #3 ·
Thanks for the reply Mark. You were right and friend of mine also confirmed that it was most likely the G2 settings. To answer your question I couldn't see the red raster even with the brightness up around 60-70.


So I did actually try to set the G2 and before I made any adjustments I read the voltages at something like 5V, 5V, -4V for the Blue, Green and Red tubes respectively. That's right, whoever adjusted them last set the red tube negative. But now I have another question for the gurus.


When I first adjusted all the G2s I had the brightness around 25. I set them all to 4V and was happy. I then played around with the brightness to see when I could start to see the raster and was pretty happy. I left the PJ on for about 15 min with the contrast and brightness at 0 and then rechecked the voltages to see that they were way off. After a couple iterations I realized that the brightness level had an effect on the voltage ... duh! SO my question is, what should the brightness be set to when adjusting the G2?


In the end I set both the contrast and brightness to 50 and set to 4V. The service manual doesn't specify anythings under the G2 adjustment, but in previous sections it mentions setting the brightness to 50. So can someone please confirm what the setting should be? Thanks!


Karl
 

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LOL, I have set the G2's negative as well..


As you are discovering, the manual is VERY vague about G2. But yes do it at 50 brightness, that's how I did it.


Now that you have this sorted out, a good mechanical setup will make a huge difference in quality - centre the image, maximise the image size and shim the guns to align the 3 colours on the screen. Your corner focus may be a little worse as you are getting close to the edge, but the image will have more brightness and better detail.


Mark
 
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