Though I always intended to build a colorizer, boards were in short supply, and I managed fine colorizing by patching subcarrier into video rate VC inputs of various modules - mostly my keyers. This was a lean approach. On a recent trip to Owego Dave Jones revealed he had 3 channel boards on a shelf along with the last RGB board. He generously gave them to me, as long as I actually built the colorizer. Considering Dave's designing a new and improved Eurorack version of the colorizer, the value for these older boards is limited, especially considering the large form factor.
Images of completion of modifying Jones keyer. I replaced the comparator and associated logic circuit with a differential amplifier - one of my last MC-1445s. I struggled with getting as much gain out of this circuit as I could. The gain is still not high enough but it's a start. A tricky part was the logic for on off and normal reverse. Thanks to Dave for help.