Author Topic: Sega CD model 2 no power issue  (Read 440 times)

megasilverx1

Sega CD model 2 no power issue
« on: July 28, 2020, 09:15:57 pm »
So I had recently purchased a Sega Genesis model 1 that had a Sega CD model 2 attached to it at a thrift store. Knowing what I know about the model 2 SCD, I had a feeling it probably wouldn't power on and to my non-surprise, it did not. I tested out the F301 fuse which is the fuse that apparently causes 99% of the no power problems, but it still seemed to be working. I also cleaned the pin connector where the Genesis goes with 91% alcohol and I don't see any problems with broken solder or a dirty connection where the AC adapter goes into the SCD. I'm not sure if this makes a huge difference outside of the location and shape of the F301 fuse, but this Sega CD 2 is one of the later models where the F301 fuse is on the bottom of the board and is a small white rectangle. I tried looking up videos on youtube but pretty much all of them just cover repairing the F301 and don't go over any other potential hardware issues these can have.

The only other thing I noticed, especially now that I'm typing this up, is that the PCB below Q301 is brown like either something leaked or burned/blew. I'm fairly certain is now the problem. Now to buy a replacement part and see if I can even fix this thing. I posted two pictures of it on my twitter https://twitter.com/MegaSilverX1/status/1288280530434379776?s=20

ffxik

Re: Sega CD model 2 no power issue
« Reply #1 on: August 01, 2020, 03:08:02 pm »
I would say you're correct.  The transistor at Q301 is known for its ability to fail catastrophically.  From the looks of it, it has.  Luckily cheap and fairly easy.  I would have a spare fuse on hand just in case you need to replace it too, or just in case something happens.


byron

Re: Sega CD model 2 no power issue
« Reply #2 on: August 01, 2020, 11:45:20 pm »
I had a few Model 2 SCDs years back and they never seemed to have problems. Are these issues something that's popped up in the last decade or so, or was I lucky?

ffxik

Re: Sega CD model 2 no power issue
« Reply #3 on: August 02, 2020, 07:57:49 pm »
I had a few Model 2 SCDs years back and they never seemed to have problems. Are these issues something that's popped up in the last decade or so, or was I lucky?

It's more to do with aging hardware. 


megasilverx1

Re: Sega CD model 2 no power issue
« Reply #4 on: August 02, 2020, 09:22:07 pm »
The part shipped yesterday with it expected to arrive on Tuesday the 4th. I ended up ordering two transistors either in the event that I screw something up or my other Sega CD 2 I've had for years gets the same issue. Hopefully it's an easy enough fix since I don't have a ton of experience with soldering. The most complicated things I've done is replace the save batteries in Game Boy games and replace a Game Boy Color speaker. Assuming the repair is successful, I'm curious if the internal battery is still alive and if the discs can be read. Or maybe like my Sega CD2, it'll read discs but will make a grinding noise from time to time.

megasilverx1

Re: Sega CD model 2 no power issue
« Reply #5 on: August 06, 2020, 10:24:56 pm »
Well I was able to remove the bad transistor...like 95% of it. The middle leg is still stuck in the PCB hole and I'm not really sure how to remove it. I've tried using solder wick and a solder sucker which both worked great for removing solder around the other two legs, but of course a simple task can't be simple for me. Any ideas on how I can remove the middle leg without damaging anything? My only idea on how to get the leg out is to heat it and use a pin or very small flathead screwdriver to push it out.

byron

Re: Sega CD model 2 no power issue
« Reply #6 on: August 07, 2020, 09:18:20 pm »
Does it have to come out, or can you just solder the new leg to that spot with the old leg still in the hole?

megasilverx1

Re: Sega CD model 2 no power issue
« Reply #7 on: August 08, 2020, 12:57:24 am »
Does it have to come out, or can you just solder the new leg to that spot with the old leg still in the hole?
I was able to remove it with a bit of wiggling and put the new transistor in. The Sega CD 2 now powers on and shows video and sound which is good. However, discs aren't spinning. The laser is moving to the starting spot on the track but it looks like it's not focusing (the actual laser isn't moving up and down). I'm wondering if someone in the 27 or so years this thing has existed pressed down on the laser eye and damaged what I just learned is called the voice coil motor. Or maybe CD drive motor is just dead; I dunno. Other than that, I did gently clean the laser with a q-tip, I'm using an official AC adapter to power the Sega CD, and the spindle doesn't seem to be messed up. Honestly, I'm just really happy I was able to get this system to turn on and I might shelve this second repair for a later time.

byron

Re: Sega CD model 2 no power issue
« Reply #8 on: August 08, 2020, 12:08:59 pm »
I wonder if a working spindle and laser assembly from another disc drive would work. I don't know how standardized they are, but it would be an interesting thing to attempt.