I think I found the cause of the trace shifting on my 485. One end
of the Position Pot (R1300) goes to +13v. The voltage drops slowly
to 11.5v as the scope "warms up". Now I just have to locate where
the +13v comes from. The power supply schematic doesn't show it, and
the reference to the A Time Base Generator schematic doesn't help.
Does anyone know where it comes from ?
Thanks, Dick, W1KSZ