[Lucien Nunes]

Thank you so much for organising this. Although it doesn't give away any secrets about the all-important composition slug, it's fun and it just possibly solves a puzzle. As I've mentioned before, the Compton electrostatic organs that I collect use a very large number of Erie resistors, typically between three and five thousand per instrument, many of which are in the 1M decade. With such a large sample, and many identical resistors used in identical circuit positions, trends emerge that would be missed when dealing with a dozen or two in a radio or TV where very few stages are electrically similar.

One such oddity is that 5M0 parts (a value specified by Compton as a step in their 2dB voicing series) are more prone to serious upward drift than other nearby values; many have reached 10MΩ or more today. If these were originally selected from the 4M7 bin and re-marked as shown in the film, we are dealing with resistors that were skewed 6% high during manufacture and then subjected to vigorous agitation after the impregnation stage, which may have affected their long-term environmental protection, microscopic structure and-or lead-to-slug contact resistance. This may not be the correct explanation as most of my examples are of later manufacture with 3-band marking, but I seem to recall the behaviour does apply equally to body-tip-dot and 3-band examples. It would be interesting to know just how the bell curve of finished product tolerance was distorted by such methods, before they reached the shelves.

I'd agree that the film is earlier than 1970. I would have put it at mid 1950s; perhaps more clues will emerge during further viewings.

Note 5M0 parts lurking in this voicing matrix: