(21-01-2018, 12:28 PM)Terry Wrote:(21-01-2018, 07:25 AM)Crackle Wrote: ... if you look at S3, a DSDP switch (or change over switch) intended I believe to switch from resistance measurement to capacitor measurement, you will see that the 2 central common terminals have been bridged together. There are 2 other wires, one from R3 R2 R1 common and one from the switch itself which are soldered together. I cant work out how these would have been fitted to the switch.
The basic function of S3 is to connect the common point of the range selection resistors or capacitors to the appropriate point in the circuit. The bridge between two central terminals is correct.
The soldered joint in mid air seems to suggest that a component has been removed at some time. I wonder if it might have been a preset to adjust the accuracy of the readings?
You've done an excellent job with that drawing but it would be more helpful if it was also converted to a normal schematic - I don't think you would want to work on one of your radios armed only with a wiring diagram, would you?
Because I found a similar method used in the internal / external battery change over switch and the wiring from the external socket removed altogether, and was wired as a single pole isolator switch, on one supply leg, to disconnect the battery by adding the copper bar across the common terminals. In other words it was not wired as a double pole change over as it should have been to change from int. to ext. battery supply.
I assumed that the R / C change over switch had also been changed by adding the small bar across the common terminals.
Terry
It is difficult for me to convert the wiring drawing into a theoretical circuit drawing when I dont know or understand how the circuit works. That is the task that I am hoping someone will help me with. All I can do at the moment is copy what I see in the hope that someone can help me.
thanks
Mike
