The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: BSA500 on 27.04. 2021 09:40
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I have just replaced the wiring loom and all was fine but the ammeter showed no charge even though the lights would brighten etc. Charging system(dynamo/DVR2) working fine. Looking at the wires I found a spare that when a multimeter attached is coming from the DVR2. I connected this to terminal 3 on the switch.
It shows no charge with lights off but does when lights on but right over to the right(6 amps) now blown the fuse. Its like the ammeter is just reading a direct charge without it passing through the battery-Help
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Forgot to add there is a power feed to a post on the switch,should I connect the A feed from the regulator to this so that it pushes a charge back to the battery???
I hate electrics,the new looms seem to have extra wires all coloured black???
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Blew the lights speedo/pilot/tail bulbs,thank god not the LED headlight.Didnt blow the battery fuse so suggests it was only feeding the lights direct
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Anybody??
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Am sitting in a carpark, so no sources to hand. But A from dvr (brown & white together for 6v, br only for 12) should go to one side of ammeter and then to switch 3 (from same side) as far as I can recall. (Makes it the same wire effectively.) Other side of ammeter goes to battery. FUSE?
F and D to dyn obvs, and the red or black to earth. Like that, nothing else connected, you should see a charge with engine running.
Lights mainly come from switch 5 from memory, via dipswitch for headlight. 4 or is it 6 for front side to switch it off with headlight on maybe, if it matters.
I wouldn't be hooking up any stray wires that seem to be dvr output A by guesswork. A is battery live too when it's in circuit so things can happen!. Also may have takeoffs for horn and or brakelight. Fuse needs to cover all current sucking wires - and a sensible one in A north of dvr is counselled by makers.
EDIT with benefit of proper PC: Switch 2 to dipswitch usually for H/L, 5 for speedo and tail and 4 for front side (to go off off with H/L on).
As Swarfy says, an ammeter won't show anything with the battery out of circuit - but lights etc should work without the battery with the engine running above tickover (with nothing showing on the ammeter). A DVR2 will allow that, like the original box would have. There should be no smoke escaping!
Your 6A charge with loads on (if it was a charge, not reversed ammeter connection showing + for -) is scary. It might be more than the odd fuse you need to replace if that happens too often.
Don't bank on brakelight at least not going through the ammeter - quite a lot seem to!
You're going to have to go back to basics as Swarfy says. Not sure what schematic you're following, but here's a typical dynamo one of the day, which I use quite often, whether for 6 or 12v, pos or neg earth. It must have been for a B31 or something, with the magdynamo, but they're all very similar. The switch on this one doesn't have the rocker arrangement with the big brass bits that you find on some, but the basics are the same.
On bikes with mags for sparks, I tend to start by getting the charging circuit hooked up and working; then the lights; then the direct feeds to brakelight and horn last. But each to his own. I would just be sure to use fuses, especially to cover the horn and brakelight circuits.
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On a standard electrical system the ammeter measures only current to and from the battery, not the current in the feed from regulator to the loom. This battery current should only be a maximum discharge of the sum of headlight, speedo, tail light wattage divided by the system voltage as in a Lights on, Engine off situation. Worth checking the ammeter for electrical competence. Is it working correctly? A blown ammeter allows no battery voltage reference to the regulator and like running without a battery allows unregulated voltage to the the lighting circuit, a possible explanation for blown bulbs. Looks like the LED headlight could only take a low current, so surplus power simply blew the remaining low wattage bulbs. This current does not register as it is on the non battery side of the ammeter.
Stop lamp and horn are on independent circuits, their wiring does not go through the ammeter.
Time to isolate the voltage regulator and get the lighting system wiring checked and working from the battery. Look for basic wiring errors, trapped wires, faulty switch, unintentional short circuits. A fuse in the battery earth lead is a simple addition to protect circuits for lights, brake light and horn.
Swarfy
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Seems like this new loom has about 3 extra wires mainly black. When I first hooked up the loom everything worked as it should bar the charging,this included the ammeter showing discharge with lights on.Of course this is a mixture of colours as the A wire is purple and there is a random peach coloured wire which has power but not on the wiring diagram supplied.
When it was in this first state i found the purple wire which was supplying power from the reg(DVR2). I wired this to 3 and as described above the ammeter showed charging with lights on(but as it turns out excessive/direct to the bulbs) but none with lights off.
Even when first connected up the lights would brighten but with no movement on the ammeter to the charge side???
I am going to have to disconnect and start again as you, Groily suggested
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Hi, My own A10 GF wiring diagram may help you and will make clear what groily was saying.
Mine is 12V pos earth with DVR2 and has lots of extra bits for sidecar but you should be able to make some sense of it, although cable colours may be different to yours (for instance it looks like your purple from DVR2 A terminal goes to Ammeter and 3 on switch also to ammeter.
Files to download is an Acrobat pdf, which can be clearer that a picture file.
Hope it helps.
Rog.
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Thank you all for the explanations and diagrams I am going to disconnect and start again I shall update when I have fixed it, and I will fix it *smile*
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OK a couple of questions observations as I try to figure this out in my head....
1.There is no power feed to the main headlight switch correct?(I only say this as since I owned this there has been a feed to terminal 5 and no wires connected to 4 so in this position everything is off). If not then it takes all its power from the reg??
2. Terminal 5 on my switch is a post with a nut on it correct?
3. My switch only has 6 terminals in total
4. Lastly(for now) what is that rocker switch on the new ones for??
many thanks Andy
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Andy. The system takes power from the regulator (output is Terminal A on the Lucas type) , or from the battery via the ammeter. Identify the power output lead from your regulator. So starting at the ammeter, one terminal carries two wires. One wire is to Terminal A/Power Output on the regulator, and the other wire carries the power to the switch. The other ammeter terminal connects to the battery. Don't forget to check polarity for correct battery fitting.
The switch has just thee required positions. As standard, 7 terminals, some have a connection the centre via a wiper. Can't answer about the rocker.
OFF... All lights off, power from terminal A will be fed through the ammeter to charge the battery, engine running above tickover.
L I'll call this "Low". Speedo bulb, rear light, parking (pilot) bulb (If fitted)
H "Headlight" This position maintains speedo and rear light, but also switches power to the dipswich, which is an either/or switch, selecting Main or Dipped Beam. Pilot light may remain lit, depending on wiring configuration.
With the engine off or idling, there will be no charge, the Lights will work and the ammeter shows a discharge. A high charge will only register with a flat battery, engine running above tickover and lights off, or almost no charge, engine running above idle, lights on, flat battery, as the regulator gives priority to lighting rather than battery charging. If the ammeter behaves the other way round, simply reverse the connections. From idle to on the road, lights will brighten as battery power is substituted for power fed directly from the dynamo via Terminal A/Regulator Output.
All straightforward. The real problem is the switch. Old, Worn, New, Faulty, the only way is to check the connections and terminals and wire up to give the functions you need. Pattern parts are notorious for internal faults and non standard internal connections.
Years ago in the absence of the proper switches we used just a single pole on/off switch and dipswitch for the lights, dispensing with the Low Light function and the dangerous low wattage Pilot Light. Speedo, Tail Light and Feed to the dipswitch all neatly joined* to the one output terminal on the switch.
Readers of a certain age will understand the backyard working practices used in making these critical connections. Make sure you take a bit more care in the interests of safety and reliability.
Original and most common connections listed below, but check your switch as already mentioned. No guarantee of anything when it comes to old electrics.
Terminal 4 on standard switch feeds Pilot Light
Terminal 3......... Feed to Switch from Ammeter
Terminal 2......... Feed to Dipswitch
Terminal 5..........Feeds Speedo and Tail Light Bulbs.
Swarfy.
* Twisted together and taped up. Definitely not the right way....
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Terminal 4 on standard switch feeds Pilot Light
Terminal 3......... Feed to Switch from Ammeter
Terminal 2......... Feed to Dipswitch
Terminal 5..........Feeds Speedo and Tail Light Bulbs.
As shown in both the diagrams. Also note the pilot light should turn off when headlight is on.
Rog.
(Edit) Photo of my A10 switch (starts no 1 terminal on left in photo).
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Yay sucess. The confusion lay in the purple wire that came from the regulator. On this loom none of the ammeter wires came with connections already on them like in the past. This meant I had 3 purple wires into the headlight shell(one feed from reg and the other others were just a loop). Once I understood how the switch etc worked(many thanks) I could figure out feeds etc and make it work. So thank again that's what these forums are all about
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Okay life throws another curve ball(I have enquired on the DVR website as well). Ammeter now goes to full 8 amp charge as the revs rise,before even with lights on maxed out at 2 amps. No changes since last year except new loom. All lights switches etc work as they should. Ammeter reads correct way battery seems happy enough but has been standing over winter.
Dynamo rises to about 19-20 volt with F&D connected(12 volt converted dynamo). AS said DVR2 fitted for a good few years with no issues and as I said all was good before winter lay up
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Andy From the DVR website the regulator is rated as a Max Output of 100 Watts on a 12 volt set up. This is close to your 8 amp or thereabouts ammeter reading.
Reckon the system is working fine, pumping power into a flattish or duff battery. Just what I would expect from a handful of throttle, no lights, and a suspect battery. Try it for a few days, see if the battery charges up and holds the charge. As the battery reaches full capacity the regulator will reduce the charge to just a trickle.
Swarfy.
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Swarfy's likely right here, but I would fully charge the battery using a charger first off. Then see what the ammeter says. Just to be sure. An amp or so would be good to see. A shedload would not be.
Because it is possible for even a DVR2 to die and if by some mischance there is a problem, you don't want to fry the dynamo . . . .
You could also run the machine with the battery disconnected, measure the voltage off A from tickover, through cut-in and on up to moderate rpm to see if it's stable. As in not more than (an admittedly spiky) 14.5 ish. All well and good if that's roughly what you see. But - if it doesn't stabilise . . . . then you're not regulating.
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Strangely hoping for a duff battery *smile*. Sounds like some good suggestions to try there thanks
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Update-Rode the bike Friday approx 30 miles with the ammeter off the scale etc. Battery voltage has not got above 12.15 volts so I suspect the battery is not a happy bunny. So bought another one( £10 from halfords) in the process off putting a good charge across it *smile*
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New battery and meter across the battery reading keeps going up 15 + volts before I chickened out
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Is the ammeter still showing a ridiculous charge, or have things settled to an amp or so regardless of what you switch on?
What voltage did you see from A to earth with the battery out of play, at 'open road' rpm?
If you aren't regulating at all, you WILL cook the dynamo, and mess up the new battery as well, so you were right to chicken out for the moment.
Just need to establish whether the regulator works or whether there is a wiring fault. Also - Make 100% certain there is no short between D and F at the dynamo, inside or out . . . Happens often enough if tags aren't carefully oriented inside, or outside connectors are poorly fitted. (Less likely with one piece tin cover, but not sure which you have.)
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So far yes ammeter really mirroring the volts at the battery, keeps on rising with revs. Haven't had the chance to run other tests yet. When tested d&f together the volts acted as they should. Dynamo end cover is metal cap and this is a 12 volt wound armature with screwed on terminals not bullet
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So there shdn't be an unwanted connection between D and F then (which would bypass the regulator and give exactly the symptoms you've got).
Assuming there isn't, then you seem to me to have a regulator that won't play, unless there is a separate prob with the F and D leads in whatever sleeving they sit between dyn and dvr2.
Suggest jury-rig of F and D from dyn to dvr if there are any 'hidden' parts of the harness to exclude that possibility, but seems probable that the regulator has gone awol from everything that you say. Could have done itself a nasty earlier on when there was confusion over the 'spare' A wires, or could just be bad luck. Easiest test is by substitution, but that's hard without one to play with I know.
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Well the unknown is the wiring as its a new loom so I could check for cross connection.
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Kay update(been away a few days). Checked green /yellow from dynamo disconnected and no cross connection. Put a probe on the d terminal of dynamo and f terminal and there was a bleep from the meter suggesting conductance. Is that not good, but it still produces plenty of volts as it should.
I found a spare DVR2 (not sure if broken or not). Put meter probes a cross d/f and got a reading of about 500,tried the found dvr and got 100 mean anything?
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There'll be connectivity between D and F, yup. Through the D brush, across the commutator to the earth brush (and thus to earth). The field coil is also (should be!)earthed one end, and the other end is at the F terminal.
We are all assuming that your dynamo is actually wired with the field coil between F terminal and earth? (Not from F to D, as per Miller systems, most 'continental' ones, or as would be necessary for a JG Regulator and perhaps some others . . .??) I think we can discount the idea that it's got 'Millerised', or you wouldn't get the output from the test you've done.
Your problem therefore seems to be simply that it isn't regulating. That might have been because D and F were touching somewhere, which would have the same effect (unregulated output) as your doing the 'bridge D to F and measure' test. But unregulated output isn't what you want off wire A to the ammeter and switch and battery.
If the voltage isn't controlled, if there isn't a short between D and F at the dyn or in the loom, and if the wiring is correctly hooked up elsewhere, then the regulator isn't doing its job.
Not sure about the 500 / 100 thing though. Just measuring from D to F leads on a brand new DVR2 in my stock, I see 210 KILO ohms give or take.
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The 100/500 readings come from the Continuity setting on the meter, so 500 is too much resistance(current DVR a d 100 to low)??
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Hi
One or two other things to check,
First is the battery OK, a battery that will not come up to full voltage will tell the regulator to keep charging
Check that the F wire to the dynamo does not become live when the lights are switched on (disconnect F at regulator first) this should check for weird connections in the loom...
I know that the DVR has a feature that limits current to the field coil. There are different versions to suit a 6v original dynamo converting to 12v or for dynamos that have the 12v armatures and field coils
Do you have the correct one?
A further check on the regulator would be to disconnect the battery, connect a voltmeter to the battery wires, fit a standard headlamp bulb, start the bike with the lights turned on
bring the revs up slowly while watching the voltmeter the voltage should stop rising somewhere near 14.7volts
You need a good true RMS meter as cheapo ones will tell lies on most bike electrics
A variable DC power source can also be used to check the regulators if you can source one ?
John
John
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Don't know what the reading should be across those leads, so can only tell you what I see on a brand new one (which was more than 0.2 Mega Ohms).
Good point from John about checking the F lead, and he reinforces the earlier point about checking the regulator output (the brown A wire basically) with the battery disconnected to see it isn't open-ended as revs rise. That is exactly what you need to do as a next move. Even a cheapo digital meter will probably give you a reasonable indication, albeit spiky as I said before. You need to know what is happening here and until you do it's ****ing into the wind.
Ref the versions of the DVR2 regulator, there are just 2 - Positive and Negative earth. The same unit, set for 12v with the white wire suppressed, is used for dynamos using original windings running at 12v, as for the after-market finer-wound '12v' armatures and fields. For 6v, the white and brown wires are spliced together, as it says on the sticker.
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OK I shall work my waythrough these tests and report back. Many thanks for all these suggestions
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Dynamo internal wiring is detailed in previous posts in the electrical section of the Forum, including a well crafted piece by Andrew at Priory Magnetos. Also Brightspark website is well worth a look. Another outfit, The Magneto Guys, don't do dynamos but have clear info about testing and dynamo pitfalls. I searched Dynamo Wiring and Dr Google once more came up with the goods.
Swarfy.
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Right plugged it all in to run the tests and guess what, yep, it's fine. The only thing was the bullet connecter for the earth wire came away so I fixed that and checked all the crimps.
So a case of bad earth???