Vectrex text display issues

[FABombjoy]

I have adjusted the two thumbwheels on the side of the logic board, I believe there are no other adjustments possible other than the DAC offset. I will make further adjustments since I learned that the diamond shapes at the bottom of the adjustment screen are the most important and when I was adjusting them I was trying to make the large central one perfect.

There are a few adjustments on the Power PCB: X and Y size, and HV, which should not be set without a scope and HV probe.

I'm afraid I already followed the advice to center using the DAC offset, as the screen was significantly off center. I have no idea how to use the yoke methods and any advice on this would be very helpful if it would improve the graphics quality.

The process in the manual requires an oscilloscope to set the DAC offset, although you might be able to put it back where it was and dial in the magnets. If you take the DAC offset too far one way or another, you'll see the vectors begin to fade out. You could possibly bring up one of the test screens and tweak the offset until it looks good, and then to center, you'll see two rings between the yoke and neck PCB. Mark them (just in case), loosen the yoke clamp, and adjust them until the image looks good and centered.

For reference, this process is at the top of page 15 in the manual.

Yes, its always the topmost or two top lines, and it only happens on certain lines of text, always the same ones and always the same amount. Is it a problem with one of the chips or on the logic board, or is it more likely a display board issue?

Last time I messed with it, things were pointing to the power board, but I had to shelve the unit to make time for other projects. I'm sitting on about 3 Vectrex units so it might be time to revisit