Sega CD model 1. Good fuses, still doesnt work....

[sk8ersublime]

Hi everyone,

I just received a Sega CD Model 1 that was tested working and shown to me working via pic from a local shop. I brought it home and I am unable to get the lights to turn on, or anything else to work from the console.

I see the "Access" and "Ready" lights flicker for a minute every now and then, but they immediately shut off. One time the disk tray opened.

My troubleshooting steps: I am using a Model 1 genesis.

1. Ring test fuses F1 and F17, tested successfully.

2. Clean board connectors on Genesis and Sega CD sub board - no luck

3. Cleaned connector pins on the expansion connector that interconnected the consoles on the Connector BD board. - no luck

4. Tested the Sega CD with another Model 1 genesis - no luck

5. Checked continuity of both ribbon cables to verify no damage was done. Tested good.

6. Replaced fuse with jumper wire to verify fuse wasnt having issue. Still does the light flickering.

7. Ring tested expansion Connectors on BD board based on the schematics found on Console5. All seem to be good.

Im at a loss and hoping someone has another idea for me check. The top port that connects to the genesis is pretty rusted, but continuity is good, however im wondering if that is my issue.

Any help will be appreciated! Thanks!

[sk8ersublime]

Also i checked the Voltage. I have 12V going across the F1 fuse, and I have 4.91V going from the Sega CD to the Genesis. The Sub board is getting about 5V and i noticed the schematic states it should be +9V.

[celerystalker]

You probably already did, but have you tried multiple AC adapters? A bad connection or wire break somewhere could account for the erratic power input.

[sk8ersublime]

You probably already did, but have you tried multiple AC adapters? A bad connection or wire break somewhere could account for the erratic power input.

Yea I have 2 model 1 Power supplies. Both tested at 12.8Vdc. It's also the same power supply it was tested working with.

Anyone have an extra they want to sell? Or one for parts? I'm located in Ellicott city, MD.

[Niku-Sama]

I am only asking this because I got a perfectly good model 2 sega cd because some one didn't do this right but....

you have both the system and the cd unit plugged in using their one adapters, correct?

[sk8ersublime]

I am only asking this because I got a perfectly good model 2 sega cd because some one didn't do this right but....

you have both the system and the cd unit plugged in using their one adapters, correct?

Yea both consoles are plugged in, each using a 1602 power adaptor.

When I flip the switch of the Genesis, the Voltage goes from 0 to 5.01 on the F17 fuse on the sub-board. It's trying to power up but something is keeping it. I guess I'll try a cap kit next.

[Niku-Sama]

I imagine the 7805 might be easier/cheaper to test before going caps to the wall on it

[jetblue]

just had a similar problem,i was googling to see if anyone else had the same problem and came across your thread.
check your dual connector. i found out mines is bad. as soon as i put in a working units connector it came to life. when i opened it it has a ferrite bar and 2 metal clips. long ago it broke probably from a fall so one of the metal clips was sliding and toched some parts:
http://img.photobucket.com/albums/v238/jetbue7/IMG_20150707_001113_zpstjvsgyfp.jpg
lucky for me i had another sega cd model 1 to swap parts or id never figure out this problem. it has small caps and rows of small resistor thingys on the other side. any of them could be shorted. im sending it to a specialist as this is beyond my ability at this time.

[sk8ersublime]

I imagine the 7805 might be easier/cheaper to test before going caps to the wall on it

I checked the input and output of the VR and it appears to be fine, 11v and 5v

[sk8ersublime]

just had a similar problem,i was googling to see if anyone else had the same problem and came across your thread.
check your dual connector. i found out mines is bad. as soon as i put in a working units connector it came to life. when i opened it it has a ferrite bar and 2 metal clips. long ago it broke probably from a fall so one of the metal clips was sliding and toched some parts:
http://img.photobucket.com/albums/v238/jetbue7/IMG_20150707_001113_zpstjvsgyfp.jpg
lucky for me i had another sega cd model 1 to swap parts or id never figure out this problem. it has small caps and rows of small resistor thingys on the other side. any of them could be shorted. im sending it to a specialist as this is beyond my ability at this time.

I thought about this as well. One of the bars was broken in my connector when i opened it, and the top connector was rusted to hell. I had to sand out the pins to clean it. I tested continuity on the pins and everything seems fine. I guess i need to look for another model 1 for a decent price.

[APE992]

Easy fix here actually:

Check every trace for continuity and you'll find one or more are broken.

[sk8ersublime]

Easy fix here actually:

Check every trace for continuity and you'll find one or more are broken.

I checked on the connector board, i need to go through the Sub board next.

Since I am getting 11V in and 5V out on the power board i would assume that is working ok?

How about pin 28? on the connector between the SegaCD and genesis? I see its labeled 9V and im getting like 4.91v, Should it be 9V or is it being regulated? Ive been trying to read up on this thing as much as i can, but the fixes are usually just change the fuse and i havent found much info on what voltages should be where. I have the repair PDF for the Mega CD, which is slightly different. I bought a Genesis + Model1 CD on ebay for a decent price "untested" but it looks like its in better condition than the one i have now. Hopefully I can build 1 good one out of the two then work on repairing the other.

Ive only repaired Arcade PCBs in the past which there is a TON of info online for. Other than that Ive been recapping a few Game Gears and Turbo Expresses.

[sk8ersublime]

Ok so Ive been checking continuity and I havent found anything broken yet. I replaced the capacitors on the Power Board and the Main board. No change in behavior :(

I jumped TR4 to try and turn on the unit and the lens clicked and once or twice the CDROM would start spinning. I never had any lights on though. The only time lights came on and stayed on was when i accidentally touched GROUND and a leg on the F17 fuse, but as expected, nothing appears on screen.

The only consistent sign of life is the lens making a clicking noise when turning on.

[jetblue]

the 7805 should be like 10v on one prong 5v on the other,middle one is ground. and the TR4 should get around 10v on both pins if i remember and 10v on its long long metal bar that solders to the board. ive made the mistake in changing these of breaking the small trace that goes from the tr4 where it solders on the large pad to the side of it where it goes down a via. may be hard to see but it indeed is a vital trace. once i saw that all these were working with different genesis systems and the same readings on a working one led me to finally check the dual connector wich is where my problem is.


if you feel all is lost you can always use my guy that i send stuff i cant fix to. pm me for deets if you want