SE/30 Micron GrayScale issues

[nottomhanks]

Hello!

Worked on the CRT board and wiring harness for the Micron XCEED card.

Didn’t turn out, so curious about what went wrong.

I’ve attached photos:

 

[wottle]

Looks like your analog board is dealing with a similar issue to my Mac Plus: https://tinkerdifferent.com/threads/diagonal-lines-on-macintosh-plus.1436/

Let me know if you find out the cause and I'll do the same.

 

[nottomhanks]

I never thought about adjusting the fly back.. interesting idea

 

[wottle]

I never thought about adjusting the fly back.. interesting idea

On the Plus, there is no adjustment on the flyback, so I'm guessing the G2 voltage is the cut off voltage controlled by R53. I could be wrong, but I didn't see any other adjustment on the flyback itself. And it made no difference. I also re-soldered all the pins on the connectors to the yoke, logic board, and CRT neck (not sure what it's official name is. No difference. I've got a U2 replacement on the way and will let you know if it makes a difference.

The one thing I have confirmed on mine is that it is the analog board. I can swap out the logic boards and get the same issue. And If I put in another analog board on the same CRT / logic board, and the issue goes away.

 

[wottle]

FYI, I received my new U2 chips from Mouser today, swapped out the chip and the video is working again. The part number is SN74LS38N and here is a link if you want to give it a shot.

https://www.mouser.com/ProductDetail/595-SN74LS38N

 

[nottomhanks]

My CRT works fine without the wiring harness and CRT board, so I don't think that's my issue.

 

[wottle]

Gotcha. I may have missed that in your post. I wonder if you can figure out what part of the Exceed board deals with the vertical sweep and maybe replace the components in that portion of the board?