06-06-2021, 09:36 PM
Very many Seven dynamos have thrown solder and are cooked looking but soldier on. If it is a 35A or M dynamo comm is wired 1 to 2 to 3 etc and the resistance between adjacent segments can be compared using the very low ohms ability of a digital meter. (The winding for 4 pole is quite different.) Shorts and poor connections show. Might be able to remedy by resoldering poor sections or digging out melted solder. Should be infinite ohms between segments and shaft. If the 3rd brush or its internal wire touches the earth brush or earth the output will increase, altho this would include the summer rate. On the 4 pole dyn the main brushes are at 90 deg which can be confusing.
Changing to a regualtor will not cure an internal problem . It has worked fine. Others on here have recently shown test using an electric drill (note direction of operation!)
If the cutout is not operating or making good connection but dyn working the red light will glow very bright , the ammeter charge reduce. The contacts can be burnished with a finger nail file but must still follow through when operated. The voltage winding about 30 ohms, the other almost none (disconnect battery before fiddling!)
If not familiar electrics, John Cornforths circuit diagram for Ruby will likely prove useful.
Changing to a regualtor will not cure an internal problem . It has worked fine. Others on here have recently shown test using an electric drill (note direction of operation!)
If the cutout is not operating or making good connection but dyn working the red light will glow very bright , the ammeter charge reduce. The contacts can be burnished with a finger nail file but must still follow through when operated. The voltage winding about 30 ohms, the other almost none (disconnect battery before fiddling!)
If not familiar electrics, John Cornforths circuit diagram for Ruby will likely prove useful.