[Phil Smith]

I reset all memory blocks on a Barco 1200 to do a setup from scratch. Now I have a bad vertical linearity problem. The photo shows the upper part of the picture very compressed and the bottom so elongated that it goes well off the tube face. Frightenly far off. This photo was taken after doing a reset without doing any adjustments:

I can fix this by using a LOT (way too much) of linearity adjustment, and some (more than I would like to) raster shift adjustment.


Is there a pot that can help with this?


Note: Before resetting, I adjusted some pots (with positive results) as outlined in this thread: http://www.avsforum.com/avs-vb/showthread.php?t=780962

 

[dominical2]

Assuming the projector is square and centered what happens when you toe in the Blue tube just a bit and then adjust the Blue horizontal width coil . Could it be the Blue lens and CRT assembly have moved ?

 

[Phil Smith]

dominical2,


I'm not worried about convergence at this point. Look at the top rectangles of the grid. They're squished very flat. The bottom rectangles are very elongated. This is because vertical linearity is horribly off. Looking thru the lens, you can see that the lower part of the grid spills over the edge and off the face of the tube, by what appears to be quite a bit (that really makes me nervous).


I can fix this with the vertical linearity adjustment, but it takes so much of the adjustment range that I almost run out. The whole reason I reset all of the memory blocks was to start over from scratch and try to avoid severe adjustments like this.

 

[Phil Smith]

I sure could use some help on this. I'd like to work on it tonight.

 

[pcCinema]

Is the linearity really wrong on the tube face or just raster position? I know you said it goes off the face but do you mean position wise or linearity wise?


If it is square on the tube face you're just mounted at too steep an angle to do anything but use extreme linearity correction.


I don't know if the 1200 has position coils or what, never had one. Should be a service manual on Curts site so you can look for adjustments.



Troy

 

[Phil Smith]

PC,


It looks to be purely a linearity problem to me. The centerline of the grid is probably not very far off center. If you compare the top rectangles to the bottom rectangles, it really shows how horribly off linearity is. It's off a LOT!


I think I have managed to fix it! (I hope.) While adjusting the P402 pot on the good V board (the one installed in the PJ), the picture started to bounce. I had 2 extra broken V boards that the picture was bouncing up and down on. I put 2 and 2 together, and realized that maybe I could fix the broken boards. I adjusted the P402 pot on the broken boards and it fixed them! The first repaired board didn't help the linearity problem at all. Linearity was exactly the same. The second repair board fixed it! Linearity is actually off in the opposite direction now, although it's minor and very manageable.

Anyone have any idea what is wrong with the V boards that have the linearity problem? Both problems are identical, so it seems to me something is probably not adjusted right.