@Red5 - yah, I get what Devster was saying in his forum about using a higher VCC point instead of the one from thr Radica 'spot'.
So, yes - I'm currently using the 3.30v VCC from thr ROM spot.
Also checking to see if any pins on the Radica are remaining in a high (+ve) or low (-ve) voltage state for too long (i.e. 'stuck').
But bear in mind folks that this is only ONE cart, and I'm not really bothered since my U.K. version of Sonic 2 works with the Radica anyway!
Also the wires are approx. 3" - or near enough! (they can't be shorter anyhow, or they won't reach the top of the new case!)
@Gannon - I think I get what you are saying by 'reading into' Devsters post on his forum...
...basically try to 'mimick' the missing pins on the Radica by creating similar voltages for them (somehow?)
Anyway folks - more interesting news!
I got a DEAD cart (Quackshot) today and decided to use the 'innards' to wire up the Radica ROM into a cart.
For those who want to try - the N/C point on Ben's diagram is actually VCC. (if yer' reading this, please update your diagram Ben!)
It is REQUIRED for the Radica ROM to power up (otherwise it's 'black screen a go-go'!)
Okay, so I thought "Great! now I can use it on a REAL MegaDrive!"
But not so...
...WHY? Well, I tried ALL region combinations (NTSC/PAL/ENG/JAP) and just got the "Produced by or under licence from SEGA enterprised Ltd." message, followed by a black screen!
Yet the ROM still works PERFECTLY on the Radica!
Hence why I listed it with a region of: - PAL/?
The only two possibles remaining are...
1. The Radica has no region (like @SgtBowhack has said all along!)
2. The Radica is based on an ASIAN MegaDrive (PAL/ASIA)
I'll test my 'theory' when my ASIAN MegaDrive arrives in the post...
That's all for now folks!