exxos's Atari, Amiga & retro forum

exxos wrote: ↑Thu Nov 29, 2018 11:19 pm I've got 68R in series with the RGB lines now... I was seeing some "shimmering" on the desktop green edges with 40R.. its pretty much gone with 68R... datasheet says use 75R so could be why.

I've tried adding and removing 50pF from the RGB lines, but doesn't seem to make any odds. Probably not needed, but will probably put a space for them on the next board just in case...

Will remove the large caps.. don't seem to do anything...

Icky wrote: ↑Thu Nov 29, 2018 11:34 pm Sounds like you have your next video circuit. Wouldnt mind seeing the latest overall schematic once you get time (might have to clone yourself first though) to update with all these mods and patches.

exxos wrote: ↑Thu Nov 29, 2018 11:44 pm

Icky wrote: ↑Thu Nov 29, 2018 11:34 pm Sounds like you have your next video circuit. Wouldnt mind seeing the latest overall schematic once you get time (might have to clone yourself first though) to update with all these mods and patches.

I will start a new thread, current one is the REV G which most mods... but will start a REV H with the 1772, DAC etc mods, probably will be after xmas as busy with booster stuff atm.

Icky wrote: ↑Fri Nov 30, 2018 12:10 am Time is always a factor. May be I’ll get you an 8 day week for Xmas or a cloning machine so you can clone yourself

exxos wrote: ↑Fri Nov 30, 2018 11:50 am This is the draft layout for version 3..

The big caps are gone. So the PCB is a little smaller now. The RGB lines I have moved over to the right as it made a lot cleaner and easier routing to the IC. All the previously grounded lower data bits are now rooted to the brightness select jumper. So there should be little more noticeable brightness jump.

I have rooted the VCC rails individually from the source point around C8. Before I had connected digital and analogue directly together on the same capacitor. So now they should be a tiny bit better noise immunity between digital and analogue power rails. They both have a separate capacitor now as well.The VCC was copper filled before, but now I have doubled up on the GND layer instead.

The RGB lines now have 75R resistors in series with them and space for some 47pF caps which will help clamp down on any random noise.

I have also added a solder pad for the blanking signal, and wired the analogue RGB inputs to ground as well.

I also rerouted the 32MHz signal away from the analogue areas.

v3.JPG

sandord wrote: ↑Fri Nov 30, 2018 11:57 am Great work! We can stick with V2 for now, right? I mean, with the leg raise + bodge wire applied.