Unfortunately, although the [https://pinoutguide.com/Video/VGAVesaDdc_pinout.shtml VGA standard should accept Csync on pin 13], some monitors expect separate v-sync and h-sync signals. The NEC LCD 1970NX, which is often referred to as the perfect monitor for Amigas or Atari STs would be an example. In those cases, an adapter, that splits c-sync into h-sync and v-sync would be required.
Don't trust sellers who claim their adapter would be able to split the signals without the need of external power. While they don't lie per sé they "forget" to tell you that this requires that the VGA monitor provides power on pin 9 - which not all of them do (e.g. again the NEC 1970). In this case you will have a simple passive adapter that does not split the signal and still requires that the monitor accepts C-sync.
See section below on how to build an adapter which is externally powered and definitely splits the signal.
== Open Source CPC2VGA PCB ==