Hitchcocks Forum

Hope this ok to post this article here if not I ask the hosts to delete.

Found this on another forum all credit to Scooter Bob for producing it, hope it may help someone.

Royal Enfield AC Lighting and Charging System


There has been some question as to the proper function of the AC lighting and charging systems in the later Enfield bikes. As the system seems to wholly reliable, not much accurate information is available for it. I have quantified a little of that information after an insidious lighting failure on a new bike in an attempt to keep other technicians from fumbling for an accurate diagnosis as I did due to a lack of good, solid technical information about the charging system.

CHARGING CIRCUIT
As with ANY electrical problem or failure, one must start from the SOURCE. Always be certain that the battery is FULLY charged and that all connections are clean and tight. Also check source fuses for continuity with a DVOM and check for corrosion on the fuse holder connections. Never rely on the “eyeball test” for a fuse or a bulb to determine whether it has failed – The DVOM doesn’t lie! After verifying that the battery’s open circuit voltage is 12.7 (lower than 12.2 will need charging!) and that all connections are clean and tight it is now time to see if the alternator’s DC charging set is functioning properly. Attach the DVOM leads to the battery at the terminals and start the bike. Watch the bikes ammeter as well. The ammeter should swing about ¾ of the way across the gauge to the “+” side. Be suspicious if it doesn’t go that far and settle down toward the centre after a bit of running. Now check your DVOM. If it doesn’t show AT LEAST 13.8VDC right off idle (about 1500-1800rpm’s max) you have a problem. Typical readings should be over 14VDC.

To diagnose the charging set in the alternator you’ll need to access the four wires coming from the alternator into the bikes wiring harness. There are two violet wires and one yellow and one orange (called amber in the service literature ...) wires in this harness. The violet wires are responsible for the generation of the two-phase AC current that is rectified and regulated into 14VDC for the battery. Disconnect the leads and measure the resistance between the two violet leads into the alternator. Use a 400ohm scale – the result should be 1.4 to 1.6ohms of resistance, depending on the internal resistance of YOUR particular DVOM. Less resistance means a shorted (truncated) winding and the alternator will not generate the required AC voltage. MORE resistance most likely means a burned or shorted to ground winding and the alternator will not work properly. Check each lead for continuity to ground at the engine case. There should be no continuity – the circuit should show open. Now check for AC voltage output with the engine running. CAUTION – You can get a nasty shock from the AC system if you ground yourself to bike whilst checking this – BE CAREFUL! Place your DVOM across the disconnected violet leads from the alternator set and check for AC voltage. The output needs to be AT LEAST 50VAC at the previously mentioned off-idle setting. The system will NOT work properly with as little as 47VAC. The electronic regulator and rectifier are QUITE sensitive to this AC input – beware! If the output is NOT at least 50VAC, the problem is in the alternator set. These potential problems will be described later in the article.

If you have the 50VAC available at the rectifier (again – hook up the wiring and VERIFY this with DVOM) and the battery still does not charge, you’ll need to look at the rectifier and the regulator assemblies. The rectifier changes the AC current to DC by basically “burning off” all the current that flows “away” from the battery and allowing the “one way” current to go through. This essentially cuts the alternators generated current IN HALF! There is also a small amount of current lost through heat and harness resistance. There should be AT LEAST 22VDC going into the regulator from the rectifier. If NOT, the rectifier is faulty. If the rectifier is allowing the proper amount of input voltage to the regulator and the battery still will not charge, the regulator is likely the culprit. VERIFY this by checking regulator output at the regulator itself (thus eliminating the possibility of the bad harness between the regulator output and the battery) – it should be battery charging voltage. NOTE: ALWAYS be mindful of engine heat during the running tests! Attach all test leads FIRST, and then start the engine! Keep the running time short and keep a fan on the engine eat all times to reduce stress and heat on the engine!

LIGHTING CIRCUIT
After verifying that the lamps in the circuit are good with a DVOM (or a new bulb …) the lighting circuit may be diagnosed in the same manner as the charging circuit – only we will be doing the voltage checks and ground checks on the YELLOW and the ORANGE (amber in the service literature …) wires instead of the violet ones. The resistance across the yellow and orange wires should be Xxohms on a 400ohm scale. There should also be NO continuity to ground at all in the windings. On the running test, there has to be at LEAST 50VAC output to the AC regulator in order for it to “turn on” and function properly. Again – if the regulator has the proper input from the alternator and the lamps still do not illuminate – check output AT the regulator, then at the bulb sockets themselves to eliminate harness problems. If the AC regulator has the proper input – but no output (it should be AT LEAST 14–18VAC) then replace the AC regulator. Beware that occasionally there will be an OVER-voltage situation if the AC regulator fails. This will blow the elements in all (or most) of the bulbs on the bike. If you get a bike with more than one bulb popped – use the DVOM to verify socket voltage BEFORE replacing the bulbs!

CAUSES FOR FAILURE
We all know that open, shorted or high-resistance in the alternator’s charging or lighting windings will cause failures. These are the most common types of failures – and are easy to verify with a little checking using a good DVOM. Be aware that there “low output” conditions that will NOT show up with a DVOM and a check of the alternator windings. One common failure is from a weak permanent magnet (rotor) piece. If the windings check OK and the output is still low, suspect a weak rotor. Also – metallic debris from normal clutch wear or a starter gear failure will attach itself to the magnet and actually disrupt the magnetic field enough to cause a low output condition. Be sure that if you find this, you completely clean the magnetic rotor and all related parts. Also be sure that the rotor isn’t touching the stator winding at all during operation. This will disrupt the magnetic field and cause the build-up of iron filings as well. A good way to prevent this during assembly is to cut a sleeve from an antifreeze jug or some other sturdy plastic and wrap the rotor with a single layer of this whilst installing the stator. This will centre the stator and assure that it isn’t touching the rotor. Also – if the stator is not centred on the rotor you will get fluctuation in the ammeter due to more charging on one side of the stator (the side closest to the magnetic rotor).

And finally – if you suspect that you DO have a low output condition at the alternator and want to verify this before teardown, as well as check the REST of the harness in the bike – here is a little “cheater”. Get a “known good” machine and park it beside the suspect bike in such a way that you can attach the four alternator output wires from the “good” bike into the wiring harness of the “bad” bike and provide a ground strap from one bike to the other. Start up the “good” bike. If the harness and all the components in that harness on the “bad” bike are well and good – the charging and lighting systems on the “bad” bike will now be working as they should from the alternator output of the “good” bike. Problem solved – tear down the primary and look for the problem in the alternator!

ScooterBob

Steve,



thanks for that, I shall have a good read of this in due course, as I may be rebuilding my Electra-X with a Machismo crankshaft and CDI alternator, which uses the AC headlight set-up.



However, due to the peculiarities of this forum, it has all been posted as one impenetrable lump which makes it difficult to read. To get the paragraph breaks to show you need to type this at the end of each paragraph of text here.





Hitting the enter/carriage return(!) button on the keyboard will only separate your paragraphs in the message composition screen, not on what the rest of us get to see.



I don't wish to be ungrateful, it just helps make it easier to read.



A.

Of course remembering to type this at the end of EVERY paragraph, as well as before AND after pictures can still be very tedious, as I appear to have missed one myself! But you get the idea. A.

Thanks for that Adrian knew about the photos but not paragraphs, I just copied and pasted.



Just trying it now


Let's see if I can get it right.



Steve

Adrian if you or anyone else wants a copy of the original send me an email here

Damm good info, damm hard to read... had a little time over coffee this morning guys...

Royal Enfield AC Lighting and Charging System Diagnosis




There has been some question as to the proper function of the AC lighting and charging systems in the later Enfield bikes. As the system seems to wholly reliable, not much accurate information is available for it. I have quantified a little of that information after an insidious lighting failure on a new bike in an attempt to keep other technicians from fumbling for an accurate diagnosis as I did due to a lack of good, solid technical information about the charging system.



CHARGING CIRCUIT

As with ANY electrical problem or failure, one must start from the SOURCE. Always be certain that the battery is FULLY charged and that all connections are clean and tight. Also check source fuses for continuity with a DVOM and check for corrosion on the fuse holder connections. Never rely on the “eyeball test” for a fuse or a bulb to determine whether it has failed – The DVOM doesn’t lie! After verifying that the battery’s open circuit voltage is 12.7 (lower than 12.2 will need charging!) and that all connections are clean and tight it is now time to see if the alternator’s DC charging set is functioning properly. Attach the DVOM leads to the battery at the terminals and start the bike. Watch the bikes ammeter as well. The ammeter should swing about ¾ of the way across the gauge to the “+” side. Be suspicious if it doesn’t go that far and settle down toward the center after a bit of running. Now check your DVOM. If it doesn’t show AT LEAST 13.8VDC right off idle (about 1500-1800rpm’s max) you have a problem. Typical readings should be over 14VDC.



To diagnose the charging set in the alternator you’ll need to access the four wires coming from the alternator into the bikes wiring harness. There are two violet wires and one yellow and one orange (called amber in the service literature ...) wires in this harness. The violet wires are responsible for the generation of the two-phase AC current that is rectified and regulated into 14VDC for the battery. Disconnect the leads and measure the resistance between the two violet leads into the alternator. Use a 400ohm scale – the result should be 1.4 to 1.6ohms of resistance, depending on the internal resistance of YOUR particular DVOM. Less resistance means a shorted (truncated) winding and the alternator will not generate the required AC voltage. MORE resistance most likely means a burned or shorted to ground winding and the alternator will not work properly. Check each lead for continuity to ground at the engine case. There should be no continuity – the circuit should show open. Now check for AC voltage output with the engine running. CAUTION – You can get a nasty shock from the AC system if you ground yourself to bike whilst checking this – BE CAREFUL! Place your DVOM across the disconnected violet leads from the alternator set and check for AC voltage. The output needs to be AT LEAST 50VAC at the previously mentioned off-idle setting. The system will NOT work properly with as little as 47VAC. The electronic regulator and rectifier are QUITE sensitive to this AC input – beware! If the output is NOT at least 50VAC, the problem is in the alternator set. These potential problems will be described later in the article.



If you have the 50VAC available at the rectifier (again – hook up the wiring and VERIFY this with DVOM) and the battery still does not charge, you’ll need to look at the rectifier and the regulator assemblies. The rectifier changes the AC current to DC by basically “burning off” all the current that flows “away” from the battery and allowing the “one way” current to go through. This essentially cuts the alternators generated current IN HALF! There is also a small amount of current lost through heat and harness resistance. There should be AT LEAST 22VDC going into the regulator from the rectifier. If NOT, the rectifier is faulty. If the rectifier is allowing the proper amount of input voltage to the regulator and the battery still will not charge, the regulator is likely the culprit. VERIFY this by checking regulator output at the regulator itself (thus eliminating the possibility of the bad harness between the regulator output and the battery) – it should be battery charging voltage. NOTE: ALWAYS be mindful of engine heat during the running tests! Attach all test leads FIRST, and then start the engine! Keep the running time short and keep a fan on the engine eat all times to reduce stress and heat on the engine!



LIGHTING CIRCUIT

After verifying that the lamps in the circuit are good with a DVOM (or a new bulb …) the lighting circuit may be diagnosed in the same manner as the charging circuit – only we will be doing the voltage checks and ground checks on the YELLOW and the ORANGE (amber in the service literature …) wires instead of the violet ones. The resistance across the yellow and orange wires should be Xxohms on a 400ohm scale. There should also be NO continuity to ground at all in the windings. On the running test, there has to be at LEAST 50VAC output to the AC regulator in order for it to “turn on” and function properly. Again – if the regulator has the proper input from the alternator and the lamps still do not illuminate – check output AT the regulator, then at the bulb sockets themselves to eliminate harness problems. If the AC regulator has the proper input – but no output (it should be AT LEAST 14–18VAC) then replace the AC regulator. Beware that occasionally there will be an OVER-voltage situation if the AC regulator fails. This will blow the elements in all (or most) of the bulbs on the bike. If you get a bike with more than one bulb popped – use the DVOM to verify socket voltage BEFORE replacing the bulbs!



CAUSES FOR FAILURE

We all know that open, shorted or high-resistance in the alternator’s charging or lighting windings will cause failures. These are the most common types of failures – and are easy to verify with a little checking using a good DVOM. Be aware that there “low output” conditions that will NOT show up with a DVOM and a check of the alternator windings. One common failure is from a weak permanent magnet (rotor) piece. If the windings check OK and the output is still low, suspect a weak rotor. Also – metallic debris from normal clutch wear or a starter gear failure will attach itself to the magnet and actually disrupt the magnetic field enough to cause a low output condition. Be sure that if you find this, you completely clean the magnetic rotor and all related parts. Also be sure that the rotor isn’t touching the stator winding at all during operation. This will disrupt the magnetic field and cause the build-up of iron filings as well. A good way to prevent this during assembly is to cut a sleeve from an antifreeze jug or some other sturdy plastic and wrap the rotor with a single layer of this whilst installing the stator. This will center the stator and assure that it isn’t touching the rotor. Also – if the stator is not centered on the rotor you will get fluctuation in the ammeter due to more charging on one side of the stator (the side closest to the magnetic rotor).



And finally – if you suspect that you DO have a low output condition at the alternator and want to verify this before teardown, as well as check the REST of the harness in the bike – here is a little “cheater”. Get a “known good” machine and park it beside the suspect bike in such a way that you can attach the four alternator output wires from the “good” bike into the wiring harness of the “bad” bike and provide a ground strap from one bike to the other. Start up the “good” bike. If the harness and all the components in that harness on the “bad” bike are well and good – the charging and lighting systems on the “bad” bike will now be working as they should from the alternator output of the “good” bike. Problem solved – tear down the primary and look for the problem in the alternator!



ScooterBob

Thanks Scaly,

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Have just read your Machine to Mate thoroughly enjoyed it great to read of others experiences looking forward to the next instalment.

Does anyone else have a problem logging in to the forum? It seems I have to log in to post after already logging in and then going to peruse other threads I have to login again

There is a bit of an annoying time-out feature on this forum, particularly if you're typing a more involved post with lots of stopping to add photos. When I can remember I will highlight and copy everything BEFORE I tick the not selling parts box and click on the Post Reply button. If it has timed out and I have to log back in, getting the reply screen up and just hitting Ctrl + V can save a lot of typing.



Nice bit of re-formatting, Scaly, that's probably how it looked when Steve copied it across.



A.

Excellent info, more like a tutorial. Thanks to Scallyback for re-formatting.