Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
08-04-2019, 08:32 PM
(This post was last modified: 08-04-2019, 08:34 PM by Bob Culver.)
An intermittent connection to or in the cutout disconnects the dyn from battery and volts rise to 30 or so. 30-6 appears across the ign bulb so glows bright. And on Summer likely to blow the field fuse.
Except for brief tests, dynamo should not be run with fied connected to output and no battery connection. Some omit Summer cahrge and for simplicity connect D and F directly at the dyn. But should Dyn lead detach dyn is then cooked.
All reasonably evident from the Cornforth diag but not from Austin wiring diags.
Joined: Aug 2017 Posts: 90 Threads: 17
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Location: Hereford
Finally found some time to have a look at the car, albeit I have to leave for work in 1/2 hour.
I've renewed the fuse and checked the dynamo by removing both D and F wires, connected a 12v bulb between live on the battery and each terminal in turn on the dynamo. Each time the bulb lights up.
I then reconnected the D wire to the dynamo and connected the bulb between the green wire
and earth but it won't light in either the summer or winter setting even when revved quite hard.
I then reconnected the green (F) wire back back on the dynamo and turned my attention to
the cut out.
Having checked both fuses were still okay, I revved the engine in summer and winter mode but
the cut-out contacts aren't closing.
Will it be safe to give them a helping hand and close them manually to see if this produces some
charge on the ammeter please?
At the moment I'm unsure why they're not closing, and why the green wire isn't lighting the bulb
when tested, and if they're linked.
My electrical knowledge is considerably limited.
Any help would be very much appreciated.
Thank you
Graham.
Joined: Aug 2017 Posts: 90 Threads: 17
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Location: Hereford
I'm hoping to have a couple of hours tomorrow when I finish work so any pointers
to help with my diagnosis would be gratefully received, even if it's to establish whether
it's the dynamo or cut-out.
Many thanks for your time.
Graham
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
Dynamo and cutout operation are exhaustively covered in posts, including recent, and club info sites.
Care is necessary fiddling with cutout.
If prodded it will normally lock operated. Must not be left like this . Pull open and/or disconnect battery.
It is vital that the input side of the cutout is not directly earthed, as by the wires from D or F terminals on cutout lying about unconnected. If cutout then prodded high current from battery to earth may wreck it.
As previous the standard test for dynamo is to remove both leads, link the terminals and connect link through an old headlamp bulb to earth. As engine revs beyond a brisk idle lamp should commence to light very bright.
