[old_tv_nut]

The retrace time in transistor sets probably got shorter over time as higher-voltage transistors became more readily available, but I don't know actual numbers. Excessive overscan was a constant complaint of Consumer Reports over the years. The excess was necessary in tube sets because of the variability in components including tubes, and the unregulated power supplies. Later solid-state sets with regulated supplies and much less variation due to the H output device could reduce the overscan without danger of producing black edges. Before the regular use of letterboxing, manufacturers avoided underscan at all costs because black edges would bring warranty claims.

Regarding variation due to the output device: tube HO's have significant voltage drop at peak current (50 to 100 volts), whereas a transistor will have a reliable saturation voltage on the order of a volt. Moto had trouble with its first transistor sets in New Orleans due to this: humidity would infiltrate the flybacks as the sets were in the warehouse. A tube (or 4-tube hybrid) set would refuse to draw terribly excessive current, and would heat up the flyback slowly enough on first use that the moisture would be driven off safely. The high voltage and scan might not be right, but would gradually correct itself. Solid state sets, however, would merrily draw all the current demanded, turning the flyback into a small pressure cooker that might crack the secondary winding. There had to be some careful fiddling with the potting compound and coil design to fix this problem while still maintaining the required fire-retardant properties and decent Q factor for efficiency.