After all my re-jigging, I'm left with an 'HD ready' 23" widescreen TV with a broken digital tuner. It's a Humax LU23-TD2. The line fed picture is pretty good. So I thought I'd use it as a monitor to replace the elderly 4:3 one on the 'spare' computer setup. I'm happy with moderate resolutions.
The spec says it does 4 resolutions - all VESA. It has the standard VGA D connector.
640 x 480 31.5 kHz 60Hz 800 x 600 37.9 ""
1024 x 768 48.4 ""
1280 x 768 48.1 ""
But I want it to work with an Acorn RPC via a KVM switch as well as the PC as per the existing setup. It works with the PC (on the resolutions within its spec) but nothing at all on the Acorn. And I've made up a monitor definition file for the Acorn to conform to those VESA specs.
Others on an Acorn list have sent me MDFs which should work - but nothing, just a blue screen with 'resolution not supported'
I'd not be surprised to find a minor timing error which would need further tweaking, but would love to know why nothing at all.
I've even rigged the the monitor and TV via a pro VGA DA so I can be absolutely sure the same signal is getting to both. No difference.
Any clues? Obviously all the standard things like sync polarity etc have been tried. Although that's part of the VESA spec anyway.