relo999 Posted October 9, 2013 Share Posted October 9, 2013 I've recently acquired a asian model 1 sega CD which at first sight the only problem with it was the fuse, but now I've replaced the fuse but it still doesn't power on. Occupationally it flickers its lights for a second (about once every 50 times) but nothing more. I do use a regular (euro) megadrive 1 AC adapter for it but for the megadrive it self I use a AC adapter for the model 2 master system (which seems to work fine on just the megadrive). Quote Link to comment Share on other sites More sharing options...
relo999 Posted October 9, 2013 Author Share Posted October 9, 2013 I've did some extra checking as I expected maybe the fuse blew again by repeated attempts at rebooting, which was just just fine. But the thing I did notice was odd as there was no voltage at the fuse (at least to me seemed odd I'm not a electric engineer or might be using the voltage meter incorrectly) Quote Link to comment Share on other sites More sharing options...
Osgeld Posted October 10, 2013 Share Posted October 10, 2013 where did you put the probes? Quote Link to comment Share on other sites More sharing options...
relo999 Posted October 10, 2013 Author Share Posted October 10, 2013 before and after the fuse, both before (and both after) the fuse and some random point's in the system. Quote Link to comment Share on other sites More sharing options...
relo999 Posted October 10, 2013 Author Share Posted October 10, 2013 I've taken a look inside again, this time with more knowing what I did. The adapter does give power to the board, or at the very least partially, as the voltage regulator does work (14 in / 13 out). Apart from that I've dissembled the whole system (except for the CD area) to for something out of the ordinary, nothing much except for some slight roughness of the power board on the underside under the heat-sink and the battery being replace and soldered with wire into place (but that seems to just fine from the looks of it). Quote Link to comment Share on other sites More sharing options...
Osgeld Posted October 11, 2013 Share Posted October 11, 2013 (edited) before and after the fuse isnt going to do much except measure the voltage drop across the fuse, millavolts you need to put black to a ground point (like the heat sink of the power board since you have it open while you are in there see what the voltage regulator is putting out (the 3 pins on the part of the heatsink, middle is ground) Edited October 11, 2013 by Osgeld Quote Link to comment Share on other sites More sharing options...
relo999 Posted October 11, 2013 Author Share Posted October 11, 2013 (edited) the voltage regulator in and out all say ~13,5V and the fuse ~14V. How can I check if the other boards get any voltage? Edited October 11, 2013 by relo999 Quote Link to comment Share on other sites More sharing options...
Osgeld Posted October 12, 2013 Share Posted October 12, 2013 there's your problem output should be 5 Quote Link to comment Share on other sites More sharing options...
relo999 Posted October 12, 2013 Author Share Posted October 12, 2013 (edited) It looks like this, how can I remove that and replace that? And could I just replace it with a regular 5V 7805 voltage regulator? Edited October 12, 2013 by relo999 Quote Link to comment Share on other sites More sharing options...
Osgeld Posted October 12, 2013 Share Posted October 12, 2013 hot air and maybe Quote Link to comment Share on other sites More sharing options...
relo999 Posted October 13, 2013 Author Share Posted October 13, 2013 (edited) I just noticed my own stupidity. I've checked the whole power board and I aperently checked the wrong thing. The actual voltage regulator says ~0.1V in / 0.01V~ out. Which it obviously shouldn't, on both sides, so there seems to be something else wrong... Edited October 13, 2013 by relo999 Quote Link to comment Share on other sites More sharing options...
relo999 Posted October 14, 2013 Author Share Posted October 14, 2013 BTW is there an easy way to check the connections on the power board? Quote Link to comment Share on other sites More sharing options...
relo999 Posted October 14, 2013 Author Share Posted October 14, 2013 I think I might have found the problem. The diode give voltage before it the arrow-ish part ~0.2V and after the input voltage ~14V. So should there be a voltage difference between both sides of the diode (D1)? Quote Link to comment Share on other sites More sharing options...
Osgeld Posted October 14, 2013 Share Posted October 14, 2013 diode will only conduct one way, and you should be getting 14V minus, eh best guess 0.7v (depends on type of diode and current draw) Quote Link to comment Share on other sites More sharing options...
relo999 Posted October 15, 2013 Author Share Posted October 15, 2013 I'm asking as I don't seem to get any voltage after the left side of the DC jack, or after TR3. Quote Link to comment Share on other sites More sharing options...
relo999 Posted October 17, 2013 Author Share Posted October 17, 2013 It seems that the transistor TR4 is broken, but what transistor do I need to replace it? Quote Link to comment Share on other sites More sharing options...
Osgeld Posted October 17, 2013 Share Posted October 17, 2013 you need to find a schematic maybe check here http://www.assemblergames.com/forums/showthread.php?44343-Sega-Service-Manuals Quote Link to comment Share on other sites More sharing options...
Yoder Posted November 10, 2013 Share Posted November 10, 2013 From what I've read, you can bridge TR4 and it will work...it will just turn on regardless of whether the power switch is on or not. It would at least allow you to further test the unit. Quote Link to comment Share on other sites More sharing options...
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