7B53A - Sweep Timing Switches


Schematic 6 (page 141 of the May88 manual) shows the switching scheme for S100A/S100B. Across the top of the diagram are the numbers for the individual switches and at the bottom, there's an arrow indicating FRONT and another arrow indicating the REAR.

As I view the switches on the board (front to rear), is the manual indicating that, for example, the fifth switch from the front is 16, the sixth switch is 15, etc., or are the switch numbers on the board itself consecutive (e.g. the fifth switch from the front is 5, the sixth switch is 6, etc.) and they simply drew the switches on the schematic in such a manner as to make it easier to follow the switches and their associated components?

I ask because something's going wrong when I switch from 1ms to 0.5ms. When I do that, 0.5ms appears to be really 5us. I have removed the switch housing from the main interface board and am going to clean the switch contacts thoroughly with IPA but if that doesn't fix it, then I think the problem might be a defective resistor or capacitor and I will need to understand exactly which switch contact goes with which associated component.

I hope that made sense...

Barry - N4BUQ