I was able to give the Mode of Operation switch a couple of good cleanings with Deoxit the other day, which produced some positive results regarding the resistance tests for the V7A (813) Socket Pins.
First, the suspect results on Pin 3 all dropped by nearly 250,000 Ohms and are all now in a quite acceptable range. There was also an improvement in a couple of the readings for Pin 4. One reading should be 40,000 Ohms and I was getting ‘Infinity’ initially. I now get 60,000 Ohms. The second reading is supposed to be 11,000 Ohms and it was also initially giving me ‘Infinity’. It now reads 700,000 Ohms. Neither is acceptable yet, but at least I have hard numbers to work with. Every little improvement helps.
In the course of doing all this work, I stumbled across a mystery on the Circuit Diagram for the Sender, as published by Canadian Marconi on Page 203 of the Operators Manual. Still have not got it all sorted out yet (maybe never will) but I will document it all shortly.
By the way, with regards to Circuit Diagrams for the 52-Set, should you ever need them, trust only those published by Canadian Marconi Company in the Operators Manual for the 52-Set. There is another set out there redrawn and included in an evaluation document for the 52-Set. These ‘copies’ have a lot of missing information and mistakes in them. Not at all reliable for serious repairs or servicing.
David
|