Zenith 25mc30 DC restoration.

[kf4rca]

I've got a Tek TSG170 that is a Japan generator. One of the color bar outputs has zero setup. But all other test signals are good.
If you think black levels were bad in NTSC, in the early days of HD, syndicated programs came in as a data file. They often had screwed up color phase, black levels, etc. And since everything was digital there was no way to correct it at the station. EVEN audio phasing (L-R) was often out of phase.