Sega Genesis CD Mod 1 only powers up when 32x is installed

[JAlvarado]

Hi,

 

I have a weird scenario.  I have a Sega Genesis Gen 1 console, Sega CD Gen 1 with JVC drive and 32x accessory.  When all are put together, everything works.  If I remove the 32x, the Sega CD does not show flashing lights or eject the drive tray.  I have replaced almost all the capacitors on the power board and the 2 aluminum electrolytic capacitors on the main board.  I have changed none of the surface mounted capacitors.  I get 5 volts on one side of the voltage regulator and 9 on the other.  On the main board, I get 5 volts on both sides of the fuse and on the positive sides of some of the capacitors.  It is hard to get to all of them with the console sitting on top.  I also get continuity on all the ground points to other ground points on the capacitors.  And continuity on all positive points to other positive points on the capacitors.

 

What could be causing the issue?

 

I am thinking about leaving it alone as I may break something else chasing this issue that does not appear if all devices are connected.

 

Thanks,

 

JAlvarado

[Jeremy Popp]

On 6/29/2020 at 3:28 PM, JAlvarado said:

Hi,

 

I have a weird scenario.  I have a Sega Genesis Gen 1 console, Sega CD Gen 1 with JVC drive and 32x accessory.  When all are put together, everything works.  If I remove the 32x, the Sega CD does not show flashing lights or eject the drive tray.  I have replaced almost all the capacitors on the power board and the 2 aluminum electrolytic capacitors on the main board.  I have changed none of the surface mounted capacitors.  I get 5 volts on one side of the voltage regulator and 9 on the other.  On the main board, I get 5 volts on both sides of the fuse and on the positive sides of some of the capacitors.  It is hard to get to all of them with the console sitting on top.  I also get continuity on all the ground points to other ground points on the capacitors.  And continuity on all positive points to other positive points on the capacitors.

 

What could be causing the issue?

 

I am thinking about leaving it alone as I may break something else chasing this issue that does not appear if all devices are connected.

 

Thanks,

 

JAlvarado

It sounds like you've really done some serious diagnostics.  The only suggestion I can come up with is to try a different Genesis console.  Do you have a spare system to test, either model 1 or 2?  I know I once found a strange combination of genesis1/CD1/32x that wouldn't output RGB video for some reason, but when I swapped the genesis, it worked.  I can't pretend I know why, but maybe the 32x is routing power through the genesis to the CD, and the genesis alone is having an issue supplying power.  You could also check the connectors between the genesis/CD to makes sure you're getting a clean connection.