Sega Master System II - Video Problem

[GamerAse]

Hello, everyone.

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:

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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.

[Gameguy]

500mA isn't enough power, that's the problem.

[GamerAse]

500mA isn't enough power, that's the problem.

I have had problems where not enough voltage would cause a console to freeze or shut down, but I am not familiar with the problems caused by not enough amperage. I'm currently trying to get an official Sega Genesis I adapter or similar so I can verify that it is indeed the adapter's fault. Would 1A be enough? I've seen posts that claim that the Sega Master System needs anywhere from 850 to 1200mA.

[FABombjoy]

Looks like either:

1: The insufficient amperage thing. Strange that only the blue channel seems to have dropped, but who knows what the systemic effects of low internal voltage might be.

2: The blue signal has disappeared from the AV port. Was RGB added to your console? I'm only familiar with NTSC SMS2 units where RF was the only output. You'd have to open it up and trace the signal from the connector to the RGB encoder to the VDP. This is contingent that you have positively ruled out cable and/or TV defects.

If you have an connection other than RGB available, you could rule out the RGB port itself by trying it out (composite or RF).

It's probably worth trying a higher amperage 9V power supply first. However, if that same adapter works with both your Mega Drive II & SNES, I'm leaning towards #2.

OEM transformers for NTSC SMS units supplied 1.2A, but I would imagine that the SMS II can work with less. I've used 1A supplies without trouble.

[Gameguy]

I have had problems where not enough voltage would cause a console to freeze or shut down, but I am not familiar with the problems caused by not enough amperage. I'm currently trying to get an official Sega Genesis I adapter or similar so I can verify that it is indeed the adapter's fault. Would 1A be enough? I've seen posts that claim that the Sega Master System needs anywhere from 850 to 1200mA.
You just mentioned how you needed to set it at 12V because it wasn't working with 9V, though the system is meant to use 9V. That's because there isn't enough amperage. I had the same problem with a Model 1 Genesis, I bought a bundle locally and it just came with a universal adapter rated 300mA. It had similar problems that you're describing and needed to be set at 12V to work, and I noticed the adapter got super hot during use. I bought a proper Sega adapter and the system worked fine without any more video or sound problems. The systems are rated at 850mA but the proper adapters are usually capable of 1.2A, I guess they wanted to be sure that there wouldn't be any problems in case the system needed more power for some reason.

[GamerAse]

Looks like either:


2: The blue signal has disappeared from the AV port. Was RGB added to your console? I'm only familiar with NTSC SMS2 units where RF was the only output. You'd have to open it up and trace the signal from the connector to the RGB encoder to the VDP. This is contingent that you have positively ruled out cable and/or TV defects.

If you have an connection other than RGB available, you could rule out the RGB port itself by trying it out (composite or RF).



The console has never been modded, I've tested with 3 different television sets and two different video cables, so i'm positive it's either the console itself (I seriously hope not) or the adapter. I am not familiar with internal specifics, but maybe the blue channel on the slot where I plug in the video cable is dead, or the wire/soldering of the component respective to the blue channel has given. I could be not making any sense, however, since I am not familiar with the Master System internals.


You just mentioned how you needed to set it at 12V because it wasn't working with 9V, though the system is meant to use 9V. That's because there isn't enough amperage. I had the same problem with a Model 1 Genesis, I bought a bundle locally and it just came with a universal adapter rated 300mA. It had similar problems that you're describing and needed to be set at 12V to work, and I noticed the adapter got super hot during use. I bought a proper Sega adapter and the system worked fine without any more video or sound problems. The systems are rated at 850mA but the proper adapters are usually capable of 1.2A, I guess they wanted to be sure that there wouldn't be any problems in case the system needed more power for some reason.

I am relieved to finally find someone with a similar problem to mine (I don't mean it in a bad way, sorry!). I will try to find a power supply with higher amperage so I can finally test it properly. Thanks so much for everyone's help.

[theclaw]

Go check thrift shops, the SMS power requirements aren't steep. You're certain to find something better. Even if you have to modify its tip polarity.