Hello all. I decided to modify my Mega Drive 1 with two switches one for 50hz and 60hz and one for language, Japanese and English I also added a bi-colour LED so when the system is in Japanese mode the LED is red, When the system is in American mode the LED is orange and when it's European it runs with a green LED. This all works but I had to also add a circuit with a 4.43mhz oscillator and a 50pf variable capacitor to get it to run in colour when in 60hz mode. My issue is the image seems distorted slightly when running in 60hz mode and there are some artefacts. 50hz without issue http://i.imgur.com/VGJTE9s.jpg 60hz issue, It's noticable around the flowers and on the blue border on the left, like vertical lines interlaced. http://i.imgur.com/U91DgOR.jpg 60hz close up. http://i.imgur.com/yBaonZE.jpg Any one know what's causing this or how I can fix it? I currently have it hooked up via Composite but I'm thinking of getting an RGB scart cable if it will help. Thanks in Advance for any help.
Can you see the chequered squares under the grass, they each have dots in them in 60hz but they are not there in 50hz, and there are vertical lines which show up all over the image. on the left of the screen on the blue border you can see the lines and at the right of the flowers. I made a small video of it http://www.youtube.com/watch?v=OG5Nsh0Yksg the lines seem to move back and forth.
Hi If you used damomonster's guide for the circuit with the 4.43mhz oscillator and a 50pf variable capacitor to get it to run in colour when in 60hz mode, I specifically remember him stating that this mod is not universal for all TVs and it could behave differently in each different TV, thus careful tuning is required. The lines moving back and forth could be caused by the variable capacitor same way the dot crawl which plagues many NEOGEO AES system out there is caused, which can be fixed by adjusting the small pot next to the oscilator by the A/V output. Likewise, adjusting the variable capacitor in your Mega Drive 1 could fix this problem. But my advice is to ditch the pesky colour fix mod and get your self a good quality RGB Scart cable with Stereo sound jack instead. They're immensely superior to Composite RCA. And while you're at it, add a 10MHZ oscillator with a switch to get your self some real power from that system, as Mega Drive 1s are very tolerable with overclocks in comparison to the pesky and cheaper Mega Drive II systems. I hope this helps!
Thanks for the responses guys. I've ordered an RGB scart cable today from ebay, when I get it will I need to remove the colour fix circuit, resolder legs 5 and 6 on the video chip and repair the trace I cut, Or can I leave it in place and the RGB cable will just work.
It will most probably work fine with the RGB, as the RGB circuit is independent from the Composite RCA. Leave it as it is and try it with the RGB 1st before you start resoldering the legs and fixing severed traces, as things could get really ugly and then sparks fly and Mega Drives die!
Just to let you all know my RGB cable came and fixes the problem completely there are now no artefacts when playing in 60hz mode. Thanks for all the help everyone
