Colecovision Rev D 5V Memory Mod issue

[m0ckery]

Hi guys,

 

I've got a PAL Rev D Colecovision that displays a black screen when powered on (no Coleco bios displayed/etc). I've tried using Expansion Module 1 and 2600 games work well - so at least I know the RF side of things works. 

 

Some of the original dram chips were quite hot to the touch so I figured I'd start troubleshooting by replacing the dram with the 5V mod. I've removed L2/L3 and the old dram chips - then linked L3 to 5V and installed sockets. I tested the connections from the dram to the VDP by the directions on the Console5 wiki and everything is connected as required there.

 

I inspected everything thoroughly before adding the sockets and all traces looked good with no obvious shorts. 

 

A voltage test at pins 8 & 9 of the dram shows a voltage of 4.9V - however pin 1 is showing a voltage of around 1.7v. This links up with the voltage on the non -5v side of L2. Does anyone have any idea of where this might be coming from?

 

Thanks in advance :)