Joined: Aug 2017 Posts: 1,746 Threads: 42
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Location: Malvern, Victoria, Australia
Ray,
"If the cut out points are not separating when the voltage is reduced what can I do to fix it please?"
My electrical knowledge is sketchy but from earlier discussions the cut out spring may have lost a little tension - it is possible to increase the spring tension by slightly bending down the bottom bracket ?
Tony.
Joined: Mar 2018 Posts: 694 Threads: 33
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Location: Lot region FRANCE
I suppose the battery terminals are clean ? If they are heavily oxidised between the lead post and the brass battery clamps, they can act as a sort of diode causing all sorts of low current problems. Ie - you can get current out for lights and starting etc, but more difficult to get stuff back into the battery.
Also, on my ignition light, there is some cotton covered resistance wire wrapped around the bulb holder - I guess to put some parallel resistance across the ignition light circuit. If that were damaged, would it make a difference ??
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
31-03-2019, 07:39 AM
(This post was last modified: 31-03-2019, 07:41 AM by Bob Culver.)
The cutout is releasing eventually. Otherwise the battery would be flat and the dynamo warm and might even smoke after long standing. Can take the cover off and watch it, but do not prod, otherwise it may stick closed
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With the cover removed I can see that the points are open (as you would expect). When I start the engine they stay open until I increase the revs at which point they close (also as you would expect) but when the engine speed dies down to a slow tick over the points do not open again unless the ignition is turned off...at which point they open immediately.
The CF1 cut out (for those who may be unfamiliar) is a single bobbin affair with the series winding (thick wire) superimposed over the shunt winding (thin wire). The shunt is working O.K. but for some reason the series winding is not pushing the points open as it should when the dynamo output falls. - Fortunately, the spring is sufficient to open the points when power is disconnected.
Maybe there is a problem with the feed wire? In my experience it is usually the very thin wire of the shunt winding that breaks - not the thick series wire. I do hope it is not another cut out rebuild.!
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Interesting developments.
I found the cut out supply wire had almost broken off at a terminal so I assumed that was the cause - but no.
I then found the blade fuse had allmost sheered but that wasn't the cause either.
It seems that the contacts will only open automatically when the tick over is at almost (but not quite) at stalling speed. I am not used to having the engine running this slowly at tick over.
Could it be the 'helper' spring gone weak perhaps?
Any suggestions as to what is happening and a solution?
(Incidentally, the battery is good with clean contacts and all the wiring is fairly recent.)
Joined: Aug 2017 Posts: 294 Threads: 11
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Now the contacts are not opening even at VERY slow ticker. !
They still open when ignition is switched off.
6 volts present at cut out.
I have noticed that the series coil seems to be missing a little insulation from it's surface in one or two places. I suspect (but only guess) that it has incorrect insulation. It looks more like matt black paint rather than a polymer or Shellac. If I am right then I have been done over again.
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
I suspect idle on most cars is too fast for the cutout to release. (Unless full retard to slow the engine).
The lost reverse current form battery will not amount to much unless idle for ages.
There will be electrical specs for cutouts somewhere but need a smoothly variable DC to test closing, and release much more complicated.
You are lucky not to have a diode to puzzle over!
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31-03-2019, 09:20 PM
(This post was last modified: 31-03-2019, 11:53 PM by Ray White.)
Bob, the contacts are now not opening at ANY engine speed. The series winding is simply not doing it's job of throwing out the contacts when the current from the dynamo falls away. I shall pay a visit to my local auto electrician tomorrow. He has a soft spot for old cars and may be able to rewind the cut out if that is what's needed.
As I mentioned before, it is ironic that before I had the cut out restored my only form of voltage control was a simple "hot wire". A heavier gauge insulated wire (it should ideally be nickel chrome) connected between the dynamo and the battery via the ignition switch and resistance calibrated. What was originally intended as a temporary measure but worked faultlessly for 20 years or more.!!
The theory is that as the battery reaches its fully charged state, resistance builds up in the transmitting resistance wire, which as suggested, heats up in a controlled manner. As the wire warms, the current to the battery slows. The dynamo is protected in the same way as the battery; by resistance slowing the current flow. The only thing to remember is that the ignition switch should never be left on for an extended period and the battery must be disconnected when being charged up.
I wouldn't go back to the hot wire set up again because it was carefully calibrated and installed by my late Father in Law who was an ingenious auto electrician.
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Location: Auckland, NZ
31-03-2019, 11:03 PM
(This post was last modified: 31-03-2019, 11:06 PM by Bob Culver.)
Hi Ray
You have lost me. Unless you have some odd non sttndard set up, it is a simple cutout not some sort of voltage regulator. Provided it drops out when switched off the drop out point is not vital. Any voltage regulation is via the reistance wire presumably now mounted under the cutout, used in conjunction with the Summer switch. The usual problem is cutout not closing due dud dynamo!
