I have an Apple II+ with Video sync issues,
Using a standard Apple composite monitor, I had vertical sync issues, and I changed a few ICs to fix it : 74LS161 x2 at D11 and D12, 74LS32 at C13 and 74LS32 at C14.
Now the image is stable with the classic monitor.
However when I use a Retrotink 2x pro, I do not get any sync (black screen). Using another Apple IIe I succeed with the retrotink.
Is there any good document explaining step by step to troubleshoot the apple II video sygnal using an Oscilloscope?
Where to start with ?