Sega CD Not Booting

[Fluffy]

I bought a Sega CD from a 2nd hand store and the damn thing won't boot.  The Genesis it came with works fine, but the CD part won't work at all.  I've checked all the connections, and the power adapter works fine...  The thing is, when I opened the system up there's this extra little board kinda glued onto the main pcb with a few wires soldered between the two.  Is that supposed to be there, or is it something added?
I'll post a pic a bit later if I can...

[Fluffy]

Alright, here's the picture.  Notice the little PC board is a different color than the main board?  It's also glued on to the main board, where everything else in the system is screwed to the shell.

CLICK ME

Sorry for camera quality, as it's taken from my cellphone...  I'm gonna probably remove that little board to see if the system works.

Btw, the mini board has 2 chips on it, one is a HD74HC04P and the other is a HD74HC74P, and the mini board has the numbers BE2200F01003, -1251V, and IC002HC74 on it, if that helps anyone identify what that board is, if not stock...

[phreak97]

it could be a multibios chip, in which case, do you want to send it to me?

removing it shouldnt make a difference if it's installed properly, having said that, it may not be installed properly.

if you remove it, make sure there are no cut traces anywhere, sometimes mods like that want you to disconnect things

[Fluffy]

Well, I removed the chip, and nothing happened.  No flames, but no function.  Tried it on 2 Genesis units too...  Any suggestions?

[Lawrence]

Those are just off-the-shelf chips, the 7404 is a hex inverter, and the 7474 is a dual flipflop.  This little PCB is a fix for an error they didn't catch before going into production, most likely.  It's not at all uncommon to see these.

[Fluffy]

Thanks for the info Lawrence.  I was just kinda suspect, since the soldering job was a little messy compared to the rest of the system.  I'll take a guess that it's just dead though, as I haven't seen any fried parts or cold solders on it...

[phreak97]

are there fuses in these?

[Fluffy]

Hmm.....   I'll have to rip it apart again next day off I get.....
Good idea though

[Guest]

Well, no fuses in it, surface-mount or otherwise as far as I can tell.....
Guess I'm stuck just using it to build a PC in...

[viletim!]

I once blew up a Mega CD by plugging a nintendo power adaptor into it (those things are killers!). The Mega CD has an opaque coating over the PCB that makes it very difficult to follow the tracks and find the faulty component. What I ended up doing is connect the voltage from the power input directly to the input of the 7805 voltage regluator, bypassing the "auto power on" circuit. It solved the problem but then I had to turn it on (I installed a switch, didn't want to have it running always) before I turned on the Mega Drive.

Maybe try something like that if no voltage is getting to the regluator.

[atom]

One of my very first posts on these forums was after I plugged my NES power adapter into my Sega CD. 9v, AC WHOOPS! Now lets see If i can do a search...

Ah, here it is http://nfg.2y.net/forum/index.php?showtopic=514&hl=
Pretty much the directions to fix it are right there, also you can see I also asked about that same PCB which I have.

And Viletim, thats pretty funny because my Sega CD unit actually has a problem with turning itself off. I would often have to pull both plugs! I now just use GENS.