I'd like to buy an old Sega Megadrive, aka Genesis outside the UK. However I don't have a TV or computer monitor to view the graphics on.

I do however have an Amstrad Ctm644, which is a 15Khz CRT without a RF tuner. The pin inis a din plug as follows: enter image description here. It is quite simple, rgb and sync.

What model megadrive would connect to this, and how?

  • it's also called Sega Megadrive in France BTW Feb 16 '20 at 14:17
  • Great, I shall expect lots of solutions from French Amstrad owners. Feb 16 '20 at 17:47

If your SMD has RGB output (as suitable for SCART), then you can try. If there is no RGB output, you might try to add PAL decoder (that converts composite signal to sync/R/G/B).

However, there are some problems you might run into:

  1. Sending composite output (sync + B/W signal + color subcarrier) to the plain monitor input for sync only might disrupt correct synchronization in the monitor.

  2. I have a suspicion that amstrad monitors require the amplitude of R/G/B signals to be significantly more than standard 1.0v peak-to-peak. At least, I've heard complaints from a person who've connected his ZX Spectrum 128k's RGB output to such monitor, that the picture was too much faded.

  • I don't have a Megadrive yet. Which models have Rgb and what form does this take? Feb 16 '20 at 16:28
  • 2
    I thought all Mega Drives had RGB output in the UK; the Nomad and Genesis III don’t, but I’m pretty sure there was never a Mega Drive III. Either way, the original and the Mega Drive II both have RGB output, as does the Multimega. See retrorgb.com/genesis.html (CDX being another name for the Multimega)
    – Tommy
    Feb 16 '20 at 17:01
  • The implication from silentdevelopment.blogspot.com/2011/07/… is that the spectrum is too bright. Feb 16 '20 at 19:44
  • 1
    This was just my conclusion from the reported data and from looking at ctm644 and amstrad cpc schematics. I had no chance to check that for sure (with an oscilloscope) to make a firm statement.
    – lvd
    Feb 16 '20 at 21:07
  • @Tommy I found this information: "Luckily both Mega Drive / Genesis consoles output composite sync as well as composite video, therefore, you just need an RGB SCART wired to support composite sync". Would such a cable, appropriately modded at the monitor end, be better? May 1 '20 at 16:18

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