I've had my Sega Master System for a long time now, and I've recently lost the original power supply during a trip. I hadn't played it for a long time, so I thought that I'd get a universal power adapter (which I also use for my SNES and Mega Drive II) and plug it in.
I got the following problem: everytime I plug in the console, the image is in a yellow/green hue. Even the "SEGA" initial logo is completely yellow. Pictures of the console, the problem and the adapter below:
I use the adapter at 12v, since 9v doesn't seem to be enough for the console (it doesn't transmit any image to the tv at 9v). The adapter I use only has 500mA, so it could be that as well. Also, the port to which I connect the AV cable has been loose for some time now, but in the past I just fidgeted with it a bit until the image showed up, and it never displayed this hue before. I0ve tried the original video RVB adapter and one of those newly made ones that I got from ebay, but both have the same problem.