I was dusting off my TDR and charging up the battery pack I rebuilt a few
years back when I noticed something interesting. In the 1982 revisions of
both the 1502 and 1503 manuals, it clearly states that the battery will not
be overcharged if the unit is left plugged in past the maximum 16 hour
recharge time. In the 1989 revision of the 1502 manual, it states exactly
the opposite. The A6 power supply board didn't change between those
revisions. The Theory of Operation sections regarding the battery charger
have changed between the different revisions, but only in phrasing. The
content remains the same, offering no explanation as to what does or does
not overcharge the battery.
Presumably the later information is the better information, but does anyone
know the story behind why it changed?