Mega Drive 1 - Not Working on my Samsung LCD
Since getting an LCD TV I found out that a lot of my retro gear wouldn't work with it. After a while I got an XRGB-2 to get around it, but I recently sold that and most of my consoles. I wanted to keep the MD tough, but it wouldn't sync properly with it, resulting in a wobbly image, made even worse when switched to 60hz mode.
After looking at my RGB cable I realised I was using the Sync signal from the Composite Video signal, I rewired my RGB cable to use the pure Sync signal (pin 7 on the Din 8 socket). But I got no image. So I wired it back to Composite Video and made a short Scart Extension lead with a Sync Seperator in it - details on GamesX, nice idea, but it didn't fix it for my MD.
I stumbled across this the other day, so thought I would try it out, it works!! I love it and now the MD is left connected to our main TV all the time.
I've tried it on 2 consoles and got the same great results, all I used is a 220uF capacitor and a 75 ohm resistor.
There's some confusion with the video chip used in the MD - the CXA1145P, all the specs say that Leg10 is C-Sync In and Leg11 is C-Sync Out. When I played around with a continuity tester in my consoles both said that Leg10 was connected to Pin7 on the Din socket? That didn't make sense, and I had nothing to lose so thought I would experiment.
The first thing I did was re-wire my RGB cable so that Scart Pin 20 was connected to Pin 7 on the Din 8 plug (C-Sync, NOT Composite Video).
With the MD in pieces, and the heatsink removed you have access to the CXA1145P and the Din socket.
I forgot to photograph all of the process, IF I do another then I'll add some more photos. But for now here's some photo's showing my work.
I found Pin 7 on the Din 8 socket, found a trace leading to it, so cut that trace.
After checking Leg 11 on the CXA1145P chip, both sides of the motherboard I could see it wasn't connected to anything, so I picked up a 220uf 10v Capacitor (I think I had removed it from a SNES RGB cable at one point) and soldered the Positive Leg of the Capacitor to Leg 11 on the CXA1145P chip. (Most capacitors mark the Negative leg for you).
Then I picked up my 75ohm resistor and insulated it with heat shrink. I soldered one end to the Negative leg of the Capacitor, bent it into shape and soldered the other end onto the rear of the Din socket (pin 7)
I re-attached the heatsink and tested the console, it worked great, it's brilliant.
A BIG thank you to the posters (MKL and viletim) in the thread where I found the information,
