Daniël Oosterhuis Posted April 29, 2016 Share Posted April 29, 2016 (edited) A year ago, I wanted to fire up my Sega MegaDrive again. Being the idiot I was, I couldn't find the AC adapter, and I figured the SNES adapter would work. As you can guess, feeding AC into a device expecting DC isn't a great idea. Anyway, at the time I just put the MegaDrive away, and later learned what I did. Anyway, today I was dusting off my consoles, as I was planning on selling some of them. Simply put, games have kind of lost my interest. I've gotten more into electronics and such, and games generally just don't hold my attention for very long, save for a few exceptions. However, I didn't want to sell my MegaDrive. Next to the interesting hardware it has, which I'm willing to experiment with once I get a bit better with electronics, the FM synthesis of the YM2612 chip just rocks. Even though a lot of Nintendo games have great music, nothing beats a good FM synth soundtrack. So, now knowing that I shouldn't use an adapter putting out AC, and that the Model 1 adapter is center negative, I went looking around for a suitable replacement. Eventually I got frustrated and just took a 12v 2A brick, opened the case, and took the soldering iron to it. All I did was swap the DC out wires, so instead of being center positive, it would be center negative. Hooked it up, the tip of the adapter fitted perfectly in the MD port, and... nothing. No LED, not a sign of life. At this point, I'm certain I blew it up. I've heard that usually in such cases, the LM7805 voltage regulators are broken. Is this true? Could there be potentially more blown parts? How should I check for those? I'm still a bit of a noob in electronics, but I'm not afraid to crack out the soldering iron and do readings with a multimeter, so throw it at me Edited April 29, 2016 by Daniël Oosterhuis Quote Link to comment Share on other sites More sharing options...
electromaster_84 Posted April 29, 2016 Share Posted April 29, 2016 (edited) I would check and see if there is a blown fuse somwhere near the power input. You could also check if power is getting to the voltage regulator with your multimeter. Pin 1 is the input voltage, pin 2 in the middle is ground, and pin 3 is the output +5v. Here's a link to the 7805 datasheet https://www.fairchildsemi.com/datasheets/LM/LM7805.pdf Also if you eventually get it working I would recommend replacing the voltage input capacitors. Edited April 29, 2016 by electromaster_84 1 Quote Link to comment Share on other sites More sharing options...
Daniël Oosterhuis Posted April 29, 2016 Author Share Posted April 29, 2016 (edited) I'll be damned. This evening I took it open to check the voltages. First, I checked the adapter hack I did. Yep, 12V DC center negative as expected. Connected it to the power and... a LED? The readings on the voltage meters were fine, 12V in, 5V out. Seems like it suddenly works again, although this time I had the metal cage off. Along the way, I reassembled it and kept checking. Right now, I have the entire plastic frame back together, expect for the main screws, and it still works. Don't know how, don't know why. Anyways, I would like to recap the MD, do you know of any page or thread where I can find which specific capacitors should be replaced and which capacitors would be best to replace them with? Edited April 29, 2016 by Daniël Oosterhuis Quote Link to comment Share on other sites More sharing options...
electromaster_84 Posted April 29, 2016 Share Posted April 29, 2016 You will have to look up which motherboard revision you have and go from there. I found some info, and one site that sell complete capacitor kits for NTSC systems. Links http://console5.com/store/kits/console-cap-kits.html?cat=120 http://console5.com/wiki/Genesis http://www.sega-16.com/forum/showthread.php?10012-Genesis-Capacitor-List Quote Link to comment Share on other sites More sharing options...
Osgeld Posted April 30, 2016 Share Posted April 30, 2016 or you can just read the side of the caps notating their values and voltages 1 Quote Link to comment Share on other sites More sharing options...
electromaster_84 Posted April 30, 2016 Share Posted April 30, 2016 well yeah the op could, but I can't because I don't own a megadrive model 1. Also there are 30+ capacitors on some of those boards. I wouldn't want to have to count and write down all those capacitor values if it wasn't necessary. Quote Link to comment Share on other sites More sharing options...
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