sega CD model 1 restting

[evildragon]

My model 1 Sega CD has worked great for me, but I've noticed something a little odd. While not a failure, doesn't seem like RAM gets cleared all the way...

When I play a game, and hit Reset, to reboot the Genesis, and eject my CD, and when I put in a CD, sometimes the game will freeze at the CD's TMSS screen.. I'll also notice, when I reboot a game, the BIOS screen with the planet, the flickering stars may be the wrong color, like pink and green....

Anyone else notice this? It doesn't bother me, because if I reboot the genesis via the powerswitch, all is well...

[Joe Redifer]

I've never seen anything like that in my 15+ years of owning a Sega CD. Maybe you should sandpaper the connection between the Genesis and the Sega CD.

[evildragon]

it's not that, it's all clean...

it's almost like the act of resetting, doesn't have the BIOS clear the word-ram completely (meaning it's completely internal as a BIOS bug)

[Joe Redifer]

Something is physically or electrically wrong internally.

[evildragon]

I just got done examining the Sega CD BIOS.. there is a glitch in the model 1 BIOS, but not all games trigger it.. When a game is reset, the VRAM isn't all cleared sometimes.. (I think it's the VRAM, it could be the system RAM).. There's a routine that sometimes gets skipped, if the game wasn't using all BIOS calls..

[Joe Redifer]

List a game that does it and I'll see if mine does the same.

[evildragon]

I don't know off-hand, but I believe resetting Snatcher during the intro (the talking scene between the two), and trying to boot Road Avenger (i think that's the name), caused a freeze..

[nik]

hold the button slightly longer to totally clear memory, could be the reboot is still too fast for it, like when they released windows XP and faster CPU's cancelled out some ops. If it works, sweet deal, but if not, I guess power on off it is. ;)

[Joe Redifer]

I recently had to replace the motherboard in my Sega CD. I'd turn it on and get the graphics of the planet, but not logos, no music and no worky! I think maybe the ASIC chip died or something. But now it works fine. I would have thought the drive would have died before anything else. Guess not.

[evildragon]

if no music and no graphics, the fuse on the motherboard probably popped.. ;) that doesn't stop the ROM from loading, but stops the motherboard from powering up..

[Joe Redifer]

I didn't see any fuse. Can you post a picture of it? Must not be a typical fuse.

[evildragon]

I didn't see any fuse. Can you post a picture of it? Must not be a typical fuse.
don't want to take apart my sega CD again (only time i took it apart was when I got it through to mail, had to fix the laser alignment as the mail man was too rough with the box)..

The fuse is small, and looks sorta like a resistor near the DC jack..

http://www.mrvfone.com.au/sega/fuse.htm

that's for a model 2 Sega CD, but the fuse looks the same in the model 1..

[Joe Redifer]

If it's near the DC jack, then that's not the problem since that is on a completely different piece than the motherboard.

[evildragon]

If it's near the DC jack, then that's not the problem since that is on a completely different piece than the motherboard.
the motherboard might have it, i don't remember the location, i never really checked as i never had this problem..

[Joe Redifer]

No, there's nothing like that on the motherboard. It's very neat and compact.

[cletus_the_red]

i have the exact same problem Model 1 cd. no boot. I looked over every board and couldnt find a fuse. power supply/video/sound chip. the one to the right of the drive. and i didnt take the drive appart. I would like to get this working! Help plz!

[evildragon]

Look at the back PCB, where the ports are connected too.. Check for a fuse, it's usually green I think, and is labled "F1"... Also check the obvious, power supply..

[cletus_the_red]

I posted a link to pics of my boards, i didnt take the cd drive appart. If you could tell me/look or take a peak to see where the fuse is. i may not be seeing it. the only green thing i see is a resister (i believe that is what it is, but i could be wrong)

my sega cd (http://frontpage.kmoraine.com/jeremy/Sega%20Genesis%20CD%20model%201%20pictures/cd.htm)

[evildragon]

http://frontpage.kmoraine.com/jeremy/Sega%20Genesis%20CD%20model%201%20pictures/Picture0%20005.jpg

It's exactly where I said, next to the DC jack.. See where under SEGA, you see a green thing, and it says "F1".. That's the fuse..

Take a wire and short both ends of that thing and test the Sega CD.. If it boots, it was a bad fuse.. BUT DONT RUN THE SEGA CD WITH IT SHORTED! Get a new fuse then, and replace it..

[cletus_the_red]

thanks man. i didnt see it, that other one had an actual tube lookin fuse. ill go try that out.

-It worked! someone else told me that was a resistor. and i didn't think anything of it. thanks a ton man!

[evildragon]

It looks like a resistor, but it's a fuse...

Glad it worked!

[cletus_the_red]

yea, i bought this off of ebay, he said he got a BSOD, and i assumed genesis was shot. (genesis worked bah! no matter i have 2x oldschool model 1's)) I took the continuity tester to the fuse, and yea it didn't connect. Could i pick up a fuse at Radioshack like that or do i need to make my own wire, and put a tube fuse in it like on this (http://www.mrvfone.com.au/sega/fuse_h.jpg) website

[evildragon]

It depends on what you want to install, as long as the amperage rating is the same, or if anything, just slightly higher (don't go lower though--yes it would save the console more, but you'd be popping the fuse just by using it sometimes)...

I think it's 2amps, not certain...

[cletus_the_red]

yea i believe it is 2 amps as well. i been hearing not any higher as well.

[Joe Redifer]

I wish my problem was just the fuse. Obviously it isn't. Oh well.

[cletus_the_red]

i edited the photo, so if someone happens to need it, its out in front of em! outlined in green, with stuff around it Identified incase someone cant find it (eh i did it anyway, although obvious) thanks again evildragon

[cletus_the_red]

Is that the only fuse, i had replaced it with a 2 amp fuse, played some sonic cd. and about 1/2 hour later it froze, and got a black screen. re set it, music went on animation. then froze. then i turned it off and back on now all i get is a still image of the space backround. and no sound. any info?

[evildragon]

Try reseating the Genesis in the Sega CD... It sounds like it's not getting to initialize the Sega CD, but is reading the ROM on it (which does require power)..

[Joe Redifer]

That's what happened to mine. You'll need a motherboard from a different Sega CD (the board that's behind the lights). I take it the SEGA and SEGA CD logo do not show up.

[evildragon]

It happened on me one time to be honest, and all I had to do was reseat the Genesis..

For a model 1, reset the card edge adapter.. It may need a little cleaning...

If it was working then, I doubt it would fail now without tripping the fuse again...

[cletus_the_red]

i did as you said, moved that adapter. and it worked! But i was listenin to the sega cd music. because i was tryin to get a copy to work. but it froze once again, and is back to just the main screen, and no music/movement. i am goin to set it sit a little bit, maybe its overheating or somthin?

[evildragon]

i did as you said, moved that adapter. and it worked! But i was listenin to the sega cd music. because i was tryin to get a copy to work. but it froze once again, and is back to just the main screen, and no music/movement. i am goin to set it sit a little bit, maybe its overheating or somthin?
doubt it's overheating, but I think your adapter may be screwed up or really dirty..

You are screwing it down, right? heat could make it expand and move a little.. that movement can freeze it up if resistance gets on the data lines..

[cletus_the_red]

the adapter on my genesis itself is clean, and i tried both genesis's i have and get the same result. i cleaned them with an erasor before. when you say adapter you mean the part that goes from the cd to the genesis? or the chip? i hope you know what i mean lol

[evildragon]

the adapter on my genesis itself is clean, and i tried both genesis's i have and get the same result. i cleaned them with an erasor before. when you say adapter you mean the part that goes from the cd to the genesis? or the chip? i hope you know what i mean lol
it's the big black block that goes on both carde edge connectors.. it connects the Sega CD to the Genesis...

when it does this, get a can of cold compressed air, and find the failing component if one is failing by heat..