Hi again
martyn_hill wrote:a) That RGB/SCART cable is probably the best one you'll find for the QL (I use one myself, as do many others here), but I believe that it is designed for RGB as opposed to CVBS. I.e. I don't know whether or not the CVBS signal is passed through.
I've since checked the wiring of that QL to SCART cable (I use the same item) and can confirm that the QL Monitor output Pin 1 (Composite PAL - CVBS) is NOT connected to the SCART Pin 20 (which is used either as CVBS or else as just the Composite SYNC, when running in RGB mode.)
Instead, Pin 1 (QL Monitor - CVBS) is connected to SCART Pin 16 - nominally 'Blanking', but depending upon the actual voltage applied, will also trigger either CVBS or RGB SCART mode of the destination TV/Monitor. Its quite a clever idea - the QL's Composite PAL/CVBS output appears to be just sufficient - even though oscillating - to trigger RGB mode by applying the necessary >0.4V (should ideally fall between 1 and 3V) to the SCART Blanking input.
Thus, your particular SCART to HDMI upscaler is ignoring the RGB signals from the QL as its designed solely for CVBS, and only receiving the QL's Composite SYNC signal.
This is why you get a steady/valid but otherwise blank display - the upscaler is dilligently and correctly converting what is effectively a blank display signal(only the SYNC)!
If that is the case, you have a couple of options:
a) Re-wire your SCART cable (in the SCART plug itself) thus:
i. Unscrew the captive fastener/strain-relief and delicately prise-apart the SCART shell.
ii. Disconnect the resistor/wire from Pin 20 (Purple wire in my SCART cable.) Tape it up or fold-away - it's not needed in CVBS mode.
iii. Disconnect the wire from Pin 16 (Orange in my SCART cable.)
iv. Re-solder the wire from Pin 16 instead to Pin 20.
v. You can leave Pin 16 unconnected, as SCART is designed to default to CVBS mode if the Blanking pin is left floating. In any case, your HDMI/SCART upscaler will probably ignore this signal pin.
vi. Close the SCART plug, careful not to crimp any of the wires and screw-back the fastener/strain relief.
or (my personal preference):
b) Leave your SCART cable intact and purchase a true RGB upscaler (as opposed to only CVBS type.)
I can recommend this one (I've no connection with the seller or eBay!) - it gives almost the full width of the QL display in RGB mode on my HDMI TV (slightly more than SCART RGB and certainly more than SCART CVBS), with only the last 8 pixels or so on the very RHS missing (this is a phenomenon of how the QL Video display cct was designed - 'overscanning') and probably the most stable and pleasing picture I get from a real QL (the new Q68 on VGA is even better!):
https://www.ebay.co.uk/itm/SCART-HDMI-t ... 2749.l2649
There are other sellers of this item, but I recently purchased a couple of these units for £21 ea. form this seller and they arrived in less than a week (in the UK.)
Let us know how you get on!