Beware of Analogue DAC SCART Cables!

I recently posted about being careful when using “MiSTer SCART cables”, as they need to have the proper resistor on the sync line.  After that post, I started getting some questions about the Analogue consoles “VGA-style” output as well – and realized I’d completely forgot to test them in my HD15-2-SCART adapter video!  Turns out, the same exact warning applies here, when connecting to SCART equipment.  More info after the links:

Analogue DAC Compatible SCART Cable:
Analogue DAC Notes:
MiSTer SCART Cable Info:

If you’d like more of the technical reasons and details behind the voltage warning, please check out the original MiSTer SCART cable post, but here’s a summary:  The Analogue DAC (and NT Mini) outputs many different signals from it’s “VGA-style” port.  All are safe to use on all devices, except one specific scenario:  RGBs through SCART equipment.  This is because the DAC outputs a higher voltage, TTL-level sync on the sync pin, which is necessary for Sega 32x support – This is represented in the picture below as “BY-AY = 2.020V”.  If you’re just going from the DAC to an RGB Monitor, you should be able to use basic VGA to BNC cables (please check your monitor’s specs to confirm), but if you’re going into SCART equipment, this is probably too high:

For SCART equipment, it’s best to drop that voltage to something within the SCART spec of about 240mV – 950mV.  Here’s that same signal run through the HD15-2-SCART, showing a perfectly safe voltage of 428mV.  As a note, that adapter also works in HV mode, so you can get safe voltage with either position of the switch:

One interesting thing to note, is the recommended resistor value of 470 ohm on the sync line is the same that’s recommended for Genesis SCART cables.  That means if you’re using a 32x with your Analogue DAC – as long as your cable is properly built – The sync will be identical to what you see above.  Here’s a scope shot anyway, just for posterity:

As a note, the Analogue DAC seems to work fine with the RetroTINK 5x.  Here’s a shot of Virtua Racing…and check out how the 32x layer is overlayed on top of the Analogue Sg’s menu that was generated by the Genesis layer!  I’ll have a 32x video out eventually that demonstrates how these layers work, but I thought I’d include this pic for fun:

For more information on analog video cables, SCART voltage concerns and how to fix them, please check out the videos below:

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