The Input Amp works, the Voltage Follower works, the VCO Bb (saw/square) works... the ring modulator doesn't. I'm confident the capture and layout are faithful to Nyle's design, but I was sure on the ENVDT, too and I had missed a diode completely and had one net wrong. Nyle took the PCB from me today and is going to play with it.
Honestly, I just think I have some bad MC1495s. They are the older Motorola parts, but are from a reputable dealer. That said, ArcadeGameChips has a big stash of the ON Semi ones. I ordered a bunch and if Nyle can't find something I did, I'll try the ON Semi chips.
On the bright side, the only module I haven't built is is the VCO Ba (sine/triangle). Because it was derived from the VCO A, and had no new circuitry, I'm very confident it will work. I'll build one this weekend just to make sure.
I'm going to hold off just a bit on the Duo-Phonic keyboard and I want to get all my modules built and racked. I need to build a couple more oscillators, filters, VCAs and then I'm calling the modular part good.
I'm still conflicted on what format exactly to use for the keyboard electronics. I could do a typical keyboard, or build it in its own standalone box with midi inputs, or even as a racked module. I want to put a Pitch Bend wheel in in place of the panel pot Nyle used, but that might be awkward on a vertical panel. Anyway, that's why I want to wait. The way it will work, I think I will build it either as a separate box or racked module. But, that's for later.