A8 and SC1224 Project

Well this is my attempt to get the A8 working on a SC1224.  I was first made interested in this project from puppetmark's amazing thread:

http://www.atariage....8-bit-in-color/

After reading his thread, I went and asked the ebay seller if he had any converter boards left.  I was happy to hear he did so I bought a couple.  When they arrived they were in a case:



Well that was cool since I didn't have to buy a case now .  Upon opening it there was the pcb.  (sorry about the esd mat it's dirty I know)



Well I tried to take out the pcb but it was affixed into the case with sticky tape.  After some gentle prying I was able to get it out:



The power, input and output options were as noted below.  They were set to take a composite input and output on the RGB header.  Power was from a set of wires.



From the original thread I knew that the board could accept a S-Video signal so I wanted to redo the connections.

Then I also thought it needed a power adapter and then why not output on the DB-9 connector.

This picture shows where these are:



Ok, so I removed the power wire and soldered in the new connectors:



At this point I am still using the composite video input since there is a jumper that must be removed to activate the S-Video input:

Here is the jumper:



But I wanted to test with the composite first just to get an idea of the difference between it and s-video.

Now I am using a Goldstar SC1224, so I need to take the sync output from this board and run it through a LM1881 seperator.

Here is the breadboard with the LM1881.



I better explain this a little.  From the DB-9 output, the yellow wire is going to be power, but for right now, I just took if from input resistor and it is using the purple wire.  The white wire from the DB-9 is audio, but I don't have that hooked up yet.

So that leaves the red, green and blue wires for the color and the black is ground and the brownish wire is sync.  There is a DIN connector on the lower left off of the breadboard but ignore that.  It is for a sega genesis I was testing on the SC1224. Also the chip at the top of the breadboard isn't being used so please disregard that too.

Ok, so I turned on everything and I did get a picture like this:



You have to ignore the moire pattern, it is an artifact from my camera.  But image is shifted over as you can see.

And there is a graininess to it, like a hatch pattern.  Ok, good enough so I went to try the s-video input.  So I removed the previously mentioned jumper and connected the s-video cable.



The resulting image on the monitor is *much* cleaner and nicer.  Although it is still shifted over.  This is the problem I have now.  I am not sure how to get this image centered.

The horizontal adjustments on the back of the monitor don't do anything to fix this issue.  Also, I had connected a sega genesis to the sc1224 earlier and it was perfectly centered.  This monitor also has been used with an Atari ST so it functions well.

Again, sorry for the moire pattern on the image...it is not there in real life, just caused by my camera.  The monitor display is very clean and crisp.




So that is my progress so far.  If anyone can suggest something to try to get the image centered that would be great.

I am no expert on video signals, but am willing to try out anything that might help here.

It is an amazing picture for sure..just need to get it centered.