Joined: Aug 2017 Posts: 3,329 Threads: 372
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Thanks, so I can discount that one. But the CFR2 has a diode and a modern resistor so wondering either of those could have failed.
Next question - should the charging light operate (with IGN on) if the dynamo is removed and the two wires to it are loose? I've found the dynamo has issues inside, but initially the whole shebang had been lighting up and indicating, quite correctly, no charge. Then after a period, the light no longer worked. Bulb of course fine. One Voltage test indicated 2 volts across terminals to bulb.
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Location: N W Kent
Presume from it's place in the circuit that the cutout relay has been replaced with a power diode and the original open wire wound resistor has been replaced with a power resistor. A basic test of the diode with a meter on the lowest Ohms resistance scale would be to make sure that you have continuity in one direction only. Just reverse the meter leads when you see continuity across the diode and continuity should disappear. With the meter on the same lowest Ohm scale you should see continuity between D and F2.
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Location: Shropshire, UK
Jon, your little sketch looks correct to me, if your car is negative earth?
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Ian - it's probably because you partially influenced it about 4 years ago! Yes, negative earth. I'll get the dynamo back together in the middle of next week and start with the Stuart checks from then. Ironically, I've put in such a good earth return system...
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Well it now charges!
I eventually did the obvious and checked if there was any power coming out of the dynamo ....nothing!
By then I had taken the switch panel apart & it was in pretty good shape. So I took the brushes out of the dynamo (bloodstained business!) All looked good....third brush had a bit of a chip out of the top, but ok, just as well as the spares in my box were wrong! I had forgotten that cleaning the commutator with the dynamo in situ was not very practicable.Put it back together and bingo! 8amps on winter charge....nothing on summer, bother, but I can live with it! I may have movedthe third brush a bit.
The dynamo is marked C 35M bn 86 No 2202186v 8-7 not clear to me what year it is. My battered spare is again a C35M bn86 but number 220198 9-6
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Location: Auckland, NZ
If wired to the llast scheme a blown summer furse or open resistor will lead to no Summer charge. John Cornforths circuit diagram from Dorset site will save you having to tediously deduce it.All the Austin diagrams contrive to be obscure.
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well done David! both those are the last incarnation dynamos so '34/5 onward?
