Trinitron.. out of alignment?

I just picked up a used Sony CPD-G520P monitor and noticed that it seems to have a problem similar to another Trinitron (an HP) I had where in certain places on the screen, vertical lines seem blurred.

It's most obvious at higher brightness levels, but I don't think it's

*caused* by high brightness, but just evident. You can really notice the effect when reading text at 1600x1200 -- a few words will be super sharp and clear, but then the next few words will be blurred out a little, and then further along the same line, it will clear up again. If I'm looking at a page full of text, the blurriness seems to zigzag up and down across the screen.

When I started writing this I was wondering if there was maybe an alignment adjustment for the monitor that affected the alignment of the beam between the lines of the aperture grille. But I'm wondering now after doing some adjustment of the convergence if that is the underlying cause. I've noticed that the convergence left-to-right is not the same at the top of the screen as it is at the bottom.. and as I adjust the convergence left to right, the effect of the blurriness seems to vary quite a bit.

I guess focus and convergence are closely related settings anyway so probably tweaking either one one way or the other could improve the clarity.

Any thoughts on this? I wonder if there's a service menu on this monitor that will let me "straighten" the convergence vertically.. if the monitor wasn't still under warranty I'd be tempted to open it up and look for some adjustments inside.

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The monitor may have a defect in the scan circuits, convergence control circuits, or something along that line. It is hard to tell by description without going in to the monitor using the service manual for reference, and making some tests from waveforms, and voltages. It is very possible that there is a fault with the dynamic focus circuits, when there is the condition of the focus not tacking across the span of the screen.

If the convergence is out of alignment, there would be colour fringing, which would be very visible when using a grating test pattern.

As for a service menu, there are no detailed set-ups for the convergence and focus in your model of monitor. The main convergence and purity is set up with a group of magnets on the rear of the CRT neck. The sides, top and bottom are set up with adhesive slip magnets on the wall of the tube. In some monitors, the corner purity and to some degree, the pin cushioning is set up with button magnets on the wall of the tube.

I would not suggest messing with any of these magnetic set-ups, unless you have had a lot of experience at this type of work. These are not easy to set up, unless you've had a lot of practice at it, and have the necessary test patterns to work with. I have seen a fair amount of monitors messed up by end users thinking they can re-align the monitor themselves.

In many of these monitor models, there is no internal service set-up. The service set-up is done with an external software using a PC computer with the factory interface kit. The cost of this would far exceed to buy a very good new computer monitor.

Jerry G.
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Jerry G.

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