thunter0512
Veteran Member
Thank you Dave. YANA is generated on board TC-2. If I remove the board the vertical line does not show up on power up.
I probed YANA on mother board pin /P and see a saw tooth pattern (click to see full size):
![IMG_20230608_234540696.jpg IMG_20230608_234540696.jpg](https://forum.vcfed.org/data/attachments/80/80011-1282228cf36a8e98bb12227b619f0898.jpg)
I also see that the 74139 latches DN signal is clocked with short 500 ns pulses repeated at 4.8 kHz.
I probed YANA on mother board pin /P and see a saw tooth pattern (click to see full size):
![IMG_20230608_234540696.jpg IMG_20230608_234540696.jpg](https://forum.vcfed.org/data/attachments/80/80011-1282228cf36a8e98bb12227b619f0898.jpg)
I also see that the 74139 latches DN signal is clocked with short 500 ns pulses repeated at 4.8 kHz.