yes, it is possible to manage the composite signal from the modulators, here you can find step by step guide we created some years ago for doing the modifies:
i think it is the easier way to obtain a composite signal from a PAL TI99.
without the modulator you can just use some converter from Component YUV2 to Composite.
It seems this is my final option, iv'e tried making a din to component cable (the output is stripey on my lcd tv as was the same as your cable Ciro), I also bought a converter box to see it that would help - it didn't. The only problem I have with the composite mod for my plastic modulator box is it looks a bit Heath Robinson, but hey if it works .. it works, so I'll look to get some components to do the mod and get it sorted.
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