Trying to wrap my head around why a particular CVBS/SVideo to VGA converter I have accepts every composite signal I feed into it, but refuses a C64C CVBS signal (which my 55" Samsung TV doesn't seem to have a problem with). Here's a capture that works (from a Timex Computer):

[![enter image description here][1]][1]

And here's the one from the C64:

[![enter image description here][2]][2]

One thing that seems evident is that the voltage amplitude of the Spectrum clone is about half of that of the C64. I've tried a series resistor to no avail. Any ideas?

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Some more info here, as I have the C64C, it outputs Luma and Chroma in separate channels. I tried to make an adapter for SVideo, but I'm still out of luck. Here's a sample of the chroma channel:

[![enter image description here][3]][3]
[![enter image description here][4]][4]

And the Luma channel:

[![enter image description here][5]][5]

Could it be that the upscaler doesn't receive enough current from these? I'm thinking in trying to boost the signal with something like this:

[![enter image description here][6]][6]

Meanwhile, I ordered a different upscaler; **though I still wished I could somehow solve this problem, as an academic exercise :)** 

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Here are a couple more of waveforms, with the CVBS of the TC2048 (blue) and the C64C (yellow) side-by-side. First, the Horizontal Blank:

[![enter image description here][7]][7] 

And the Vertical Blank:

[![enter image description here][8]][8]

A couple more detailed waveform on each Vertical Blank:

[![enter image description here][9]][9]
[![enter image description here][10]][10]


  [1]: https://i.sstatic.net/vax0E.png
  [2]: https://i.sstatic.net/rndVD.png
  [3]: https://i.sstatic.net/unhwa.png
  [4]: https://i.sstatic.net/40gqB.png
  [5]: https://i.sstatic.net/bTQ8i.png
  [6]: https://i.sstatic.net/ZVylg.png
  [7]: https://i.sstatic.net/zM9a8.png
  [8]: https://i.sstatic.net/Yajqu.png
  [9]: https://i.sstatic.net/MFwSA.png
  [10]: https://i.sstatic.net/HGp94.png