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+--- Thread: Power TO the dynamo! (/showthread.php?tid=5081)
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RE: Power TO the dynamo! - JonE - 17-10-2020
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.
RE: Power TO the dynamo! - Stuart Giles - 17-10-2020
(17-10-2020, 09:18 AM)JonE Wrote: should the charging light operate (with IGN on) if the dynamo is removed and the two wires to it are loose?
The light shouldn't be on if the 'D' connection isn't made with the ignition turned on. The light's circuit relies on a chassis earth (via the dynamo) to be fully made.
Is the modern resistor connected somewhere between the 'D' and 'F2' terminals? if so it's probably replacing the original open wire wound item.
Can you put up a diagram or maybe a photo of what the Diode is wired to so that someone on here can work out what it's supposed to be doing?
RE: Power TO the dynamo! - JonE - 17-10-2020
this is from my file. I'm pretty sure i've tested it before a few years ago... but not sure how likely to failure any of the items are...
RE: Power TO the dynamo! - Stuart Giles - 17-10-2020
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.
RE: Power TO the dynamo! - Ian McGowan - 18-10-2020
Jon, your little sketch looks correct to me, if your car is negative earth?
RE: Power TO the dynamo! - JonE - 18-10-2020
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...
RE: Power TO the dynamo! - David.H - 20-10-2020
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
RE: Power TO the dynamo! - Bob Culver - 21-10-2020
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.
RE: Power TO the dynamo! - JonE - 21-10-2020
well done David! both those are the last incarnation dynamos so '34/5 onward?